CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
Home > CWE List > VIEW SLICE: CWE-677: Weakness Base Elements (3.0)  
ID

CWE VIEW: Weakness Base Elements

View ID: 677
Type: Implicit
Status: Draft
+ Objective
This view (slice) displays only weakness base elements.
+ Filter
/Weakness_Catalog/Weaknesses/Weakness[@Abstraction='Base']
+ Membership
NatureTypeIDName
HasMemberBaseBase14Compiler Removal of Code to Clear Buffers
HasMemberBaseBase15External Control of System or Configuration Setting
HasMemberBaseBase23Relative Path Traversal
HasMemberBaseBase36Absolute Path Traversal
HasMemberBaseBase41Improper Resolution of Path Equivalence
HasMemberBaseBase59Improper Link Resolution Before File Access ('Link Following')
HasMemberBaseBase66Improper Handling of File Names that Identify Virtual Resources
HasMemberBaseBase76Improper Neutralization of Equivalent Special Elements
HasMemberBaseBase78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
HasMemberBaseBase79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
HasMemberBaseBase88Argument Injection or Modification
HasMemberBaseBase89Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
HasMemberBaseBase90Improper Neutralization of Special Elements used in an LDAP Query ('LDAP Injection')
HasMemberBaseBase91XML Injection (aka Blind XPath Injection)
HasMemberDeprecatedDeprecated92DEPRECATED: Improper Sanitization of Custom Special Characters
HasMemberBaseBase93Improper Neutralization of CRLF Sequences ('CRLF Injection')
HasMemberBaseBase95Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
HasMemberBaseBase96Improper Neutralization of Directives in Statically Saved Code ('Static Code Injection')
HasMemberBaseBase98Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')
HasMemberBaseBase99Improper Control of Resource Identifiers ('Resource Injection')
HasMemberBaseBase111Direct Use of Unsafe JNI
HasMemberBaseBase112Missing XML Validation
HasMemberBaseBase113Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')
HasMemberBaseBase114Process Control
HasMemberBaseBase115Misinterpretation of Input
HasMemberBaseBase117Improper Output Neutralization for Logs
HasMemberBaseBase120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
HasMemberBaseBase123Write-what-where Condition
HasMemberBaseBase124Buffer Underwrite ('Buffer Underflow')
HasMemberBaseBase125Out-of-bounds Read
HasMemberBaseBase128Wrap-around Error
HasMemberBaseBase129Improper Validation of Array Index
HasMemberBaseBase130Improper Handling of Length Parameter Inconsistency
HasMemberBaseBase131Incorrect Calculation of Buffer Size
HasMemberDeprecatedDeprecated132DEPRECATED (Duplicate): Miscalculated Null Termination
HasMemberBaseBase134Use of Externally-Controlled Format String
HasMemberBaseBase135Incorrect Calculation of Multi-Byte String Length
HasMemberBaseBase140Improper Neutralization of Delimiters
HasMemberBaseBase166Improper Handling of Missing Special Element
HasMemberBaseBase167Improper Handling of Additional Special Element
HasMemberBaseBase168Improper Handling of Inconsistent Special Elements
HasMemberBaseBase170Improper Null Termination
HasMemberBaseBase178Improper Handling of Case Sensitivity
HasMemberBaseBase179Incorrect Behavior Order: Early Validation
HasMemberBaseBase180Incorrect Behavior Order: Validate Before Canonicalize
HasMemberBaseBase181Incorrect Behavior Order: Validate Before Filter
HasMemberBaseBase182Collapse of Data into Unsafe Value
HasMemberBaseBase183Permissive Whitelist
HasMemberBaseBase184Incomplete Blacklist
HasMemberBaseBase186Overly Restrictive Regular Expression
HasMemberBaseBase187Partial Comparison
HasMemberBaseBase188Reliance on Data/Memory Layout
HasMemberBaseBase190Integer Overflow or Wraparound
HasMemberBaseBase191Integer Underflow (Wrap or Wraparound)
HasMemberBaseBase193Off-by-one Error
HasMemberBaseBase194Unexpected Sign Extension
HasMemberBaseBase197Numeric Truncation Error
HasMemberBaseBase198Use of Incorrect Byte Ordering
HasMemberBaseBase204Response Discrepancy Information Exposure
HasMemberBaseBase205Information Exposure Through Behavioral Discrepancy
HasMemberBaseBase208Information Exposure Through Timing Discrepancy
HasMemberBaseBase209Information Exposure Through an Error Message
HasMemberBaseBase210Information Exposure Through Self-generated Error Message
HasMemberBaseBase211Information Exposure Through Externally-Generated Error Message
HasMemberBaseBase212Improper Cross-boundary Removal of Sensitive Data
HasMemberBaseBase213Intentional Information Exposure
HasMemberDeprecatedDeprecated217DEPRECATED: Failure to Protect Stored Data from Modification
HasMemberDeprecatedDeprecated218DEPRECATED (Duplicate): Failure to provide confidentiality for stored data
HasMemberBaseBase222Truncation of Security-relevant Information
HasMemberBaseBase223Omission of Security-relevant Information
HasMemberBaseBase224Obscured Security-relevant Information by Alternate Name
HasMemberDeprecatedDeprecated225DEPRECATED (Duplicate): General Information Management Problems
HasMemberBaseBase226Sensitive Information Uncleared Before Release
HasMemberBaseBase229Improper Handling of Values
HasMemberBaseBase233Improper Handling of Parameters
HasMemberBaseBase237Improper Handling of Structural Elements
HasMemberBaseBase240Improper Handling of Inconsistent Structural Elements
HasMemberBaseBase241Improper Handling of Unexpected Data Type
HasMemberBaseBase242Use of Inherently Dangerous Function
HasMemberDeprecatedDeprecated247DEPRECATED (Duplicate): Reliance on DNS Lookups in a Security Decision
HasMemberBaseBase248Uncaught Exception
HasMemberBaseBase252Unchecked Return Value
HasMemberBaseBase253Incorrect Check of Function Return Value
HasMemberBaseBase257Storing Passwords in a Recoverable Format
HasMemberBaseBase259Use of Hard-coded Password
HasMemberBaseBase263Password Aging with Long Expiration
HasMemberBaseBase266Incorrect Privilege Assignment
HasMemberBaseBase267Privilege Defined With Unsafe Actions
HasMemberBaseBase268Privilege Chaining
HasMemberBaseBase270Privilege Context Switching Error
HasMemberBaseBase272Least Privilege Violation
HasMemberBaseBase273Improper Check for Dropped Privileges
HasMemberBaseBase274Improper Handling of Insufficient Privileges
HasMemberBaseBase280Improper Handling of Insufficient Permissions or Privileges
HasMemberBaseBase281Improper Preservation of Permissions
HasMemberBaseBase283Unverified Ownership
HasMemberBaseBase288Authentication Bypass Using an Alternate Path or Channel
HasMemberBaseBase290Authentication Bypass by Spoofing
HasMemberBaseBase294Authentication Bypass by Capture-replay
HasMemberBaseBase295Improper Certificate Validation
HasMemberBaseBase296Improper Following of a Certificate's Chain of Trust
HasMemberBaseBase299Improper Check for Certificate Revocation
HasMemberBaseBase303Incorrect Implementation of Authentication Algorithm
HasMemberBaseBase304Missing Critical Step in Authentication
HasMemberBaseBase305Authentication Bypass by Primary Weakness
HasMemberBaseBase307Improper Restriction of Excessive Authentication Attempts
HasMemberBaseBase308Use of Single-factor Authentication
HasMemberBaseBase309Use of Password System for Primary Authentication
HasMemberBaseBase311Missing Encryption of Sensitive Data
HasMemberBaseBase312Cleartext Storage of Sensitive Information
HasMemberBaseBase319Cleartext Transmission of Sensitive Information
HasMemberBaseBase321Use of Hard-coded Cryptographic Key
HasMemberBaseBase322Key Exchange without Entity Authentication
HasMemberBaseBase323Reusing a Nonce, Key Pair in Encryption
HasMemberBaseBase324Use of a Key Past its Expiration Date
HasMemberBaseBase325Missing Required Cryptographic Step
HasMemberBaseBase327Use of a Broken or Risky Cryptographic Algorithm
HasMemberBaseBase328Reversible One-Way Hash
HasMemberBaseBase331Insufficient Entropy
HasMemberBaseBase334Small Space of Random Values
HasMemberBaseBase335Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG)
HasMemberBaseBase336Same Seed in Pseudo-Random Number Generator (PRNG)
HasMemberBaseBase337Predictable Seed in Pseudo-Random Number Generator (PRNG)
HasMemberBaseBase338Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
HasMemberBaseBase339Small Seed Space in PRNG
HasMemberBaseBase341Predictable from Observable State
HasMemberBaseBase342Predictable Exact Value from Previous Values
HasMemberBaseBase343Predictable Value Range from Previous Values
HasMemberBaseBase344Use of Invariant Value in Dynamically Changing Context
HasMemberBaseBase346Origin Validation Error
HasMemberBaseBase347Improper Verification of Cryptographic Signature
HasMemberBaseBase348Use of Less Trusted Source
HasMemberBaseBase349Acceptance of Extraneous Untrusted Data With Trusted Data
HasMemberBaseBase351Insufficient Type Distinction
HasMemberBaseBase353Missing Support for Integrity Check
HasMemberBaseBase354Improper Validation of Integrity Check Value
HasMemberBaseBase356Product UI does not Warn User of Unsafe Actions
HasMemberBaseBase357Insufficient UI Warning of Dangerous Operations
HasMemberBaseBase358Improperly Implemented Security Check for Standard
HasMemberBaseBase360Trust of System Event Data
HasMemberBaseBase363Race Condition Enabling Link Following
HasMemberBaseBase364Signal Handler Race Condition
HasMemberBaseBase365Race Condition in Switch
HasMemberBaseBase366Race Condition within a Thread
HasMemberBaseBase367Time-of-check Time-of-use (TOCTOU) Race Condition
HasMemberBaseBase368Context Switching Race Condition
HasMemberBaseBase369Divide By Zero
HasMemberBaseBase372Incomplete Internal State Distinction
HasMemberDeprecatedDeprecated373DEPRECATED: State Synchronization Error
HasMemberBaseBase374Passing Mutable Objects to an Untrusted Method
HasMemberBaseBase375Returning a Mutable Object to an Untrusted Caller
HasMemberBaseBase377Insecure Temporary File
HasMemberBaseBase378Creation of Temporary File With Insecure Permissions
HasMemberBaseBase379Creation of Temporary File in Directory with Incorrect Permissions
HasMemberBaseBase385Covert Timing Channel
HasMemberBaseBase386Symbolic Name not Mapping to Correct Object
HasMemberBaseBase391Unchecked Error Condition
HasMemberBaseBase392Missing Report of Error Condition
HasMemberBaseBase393Return of Wrong Status Code
HasMemberBaseBase394Unexpected Status Code or Return Value
HasMemberBaseBase395Use of NullPointerException Catch to Detect NULL Pointer Dereference
HasMemberBaseBase396Declaration of Catch for Generic Exception
HasMemberBaseBase397Declaration of Throws for Generic Exception
HasMemberBaseBase400Uncontrolled Resource Consumption ('Resource Exhaustion')
HasMemberBaseBase401Improper Release of Memory Before Removing Last Reference ('Memory Leak')
HasMemberBaseBase403Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')
HasMemberBaseBase404Improper Resource Shutdown or Release
HasMemberBaseBase406Insufficient Control of Network Message Volume (Network Amplification)
HasMemberBaseBase407Algorithmic Complexity
HasMemberBaseBase408Incorrect Behavior Order: Early Amplification
HasMemberBaseBase409Improper Handling of Highly Compressed Data (Data Amplification)
HasMemberBaseBase410Insufficient Resource Pool
HasMemberBaseBase412Unrestricted Externally Accessible Lock
HasMemberBaseBase413Improper Resource Locking
HasMemberBaseBase414Missing Lock Check
HasMemberBaseBase416Use After Free
HasMemberBaseBase419Unprotected Primary Channel
HasMemberBaseBase420Unprotected Alternate Channel
HasMemberBaseBase421Race Condition During Access to Alternate Channel
HasMemberDeprecatedDeprecated423DEPRECATED (Duplicate): Proxied Trusted Channel
HasMemberBaseBase425Direct Request ('Forced Browsing')
HasMemberBaseBase427Uncontrolled Search Path Element
HasMemberBaseBase428Unquoted Search Path or Element
HasMemberBaseBase430Deployment of Wrong Handler
HasMemberBaseBase431Missing Handler
HasMemberBaseBase432Dangerous Signal Handler not Disabled During Sensitive Operations
HasMemberBaseBase434Unrestricted Upload of File with Dangerous Type
HasMemberBaseBase436Interpretation Conflict
HasMemberBaseBase437Incomplete Model of Endpoint Features
HasMemberBaseBase439Behavioral Change in New Version or Environment
HasMemberBaseBase440Expected Behavior Violation
HasMemberDeprecatedDeprecated443DEPRECATED (Duplicate): HTTP response splitting
HasMemberBaseBase444Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')
HasMemberBaseBase446UI Discrepancy for Security Feature
HasMemberBaseBase447Unimplemented or Unsupported Feature in UI
HasMemberBaseBase448Obsolete Feature in UI
HasMemberBaseBase449The UI Performs the Wrong Action
HasMemberBaseBase450Multiple Interpretations of UI Input
HasMemberBaseBase453Insecure Default Variable Initialization
HasMemberBaseBase454External Initialization of Trusted Variables or Data Stores
HasMemberBaseBase455Non-exit on Failed Initialization
HasMemberBaseBase456Missing Initialization of a Variable
HasMemberDeprecatedDeprecated458DEPRECATED: Incorrect Initialization
HasMemberBaseBase459Incomplete Cleanup
HasMemberBaseBase462Duplicate Key in Associative List (Alist)
HasMemberBaseBase463Deletion of Data Structure Sentinel
HasMemberBaseBase464Addition of Data Structure Sentinel
HasMemberBaseBase466Return of Pointer Value Outside of Expected Range
HasMemberBaseBase468Incorrect Pointer Scaling
HasMemberBaseBase469Use of Pointer Subtraction to Determine Size
HasMemberBaseBase470Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
HasMemberBaseBase471Modification of Assumed-Immutable Data (MAID)
HasMemberBaseBase472External Control of Assumed-Immutable Web Parameter
HasMemberBaseBase474Use of Function with Inconsistent Implementations
HasMemberBaseBase475Undefined Behavior for Input to API
HasMemberBaseBase476NULL Pointer Dereference
HasMemberBaseBase477Use of Obsolete Function
HasMemberBaseBase480Use of Incorrect Operator
HasMemberBaseBase484Omitted Break Statement in Switch
HasMemberBaseBase489Leftover Debug Code
HasMemberBaseBase494Download of Code Without Integrity Check
HasMemberBaseBase501Trust Boundary Violation
HasMemberBaseBase507Trojan Horse
HasMemberBaseBase508Non-Replicating Malicious Code
HasMemberBaseBase509Replicating Malicious Code (Virus or Worm)
HasMemberBaseBase510Trapdoor
HasMemberBaseBase511Logic/Time Bomb
HasMemberBaseBase512Spyware
HasMemberBaseBase515Covert Storage Channel
HasMemberDeprecatedDeprecated516DEPRECATED (Duplicate): Covert Timing Channel
HasMemberBaseBase521Weak Password Requirements
HasMemberBaseBase522Insufficiently Protected Credentials
HasMemberBaseBase538File and Directory Information Exposure
HasMemberBaseBase544Missing Standardized Error Handling Mechanism
HasMemberBaseBase551Incorrect Behavior Order: Authorization Before Parsing and Canonicalization
HasMemberBaseBase552Files or Directories Accessible to External Parties
HasMemberBaseBase562Return of Stack Variable Address
HasMemberBaseBase565Reliance on Cookies without Validation and Integrity Checking
HasMemberBaseBase567Unsynchronized Access to Shared Data in a Multithreaded Context
HasMemberBaseBase581Object Model Violation: Just One of Equals and Hashcode Defined
HasMemberBaseBase584Return Inside Finally Block
HasMemberBaseBase587Assignment of a Fixed Address to a Pointer
HasMemberBaseBase595Comparison of Object References Instead of Object Contents
HasMemberBaseBase596Incorrect Semantic Object Comparison
HasMemberBaseBase600Uncaught Exception in Servlet
HasMemberBaseBase602Client-Side Enforcement of Server-Side Security
HasMemberBaseBase603Use of Client-Side Authentication
HasMemberBaseBase605Multiple Binds to the Same Port
HasMemberBaseBase606Unchecked Input for Loop Condition
HasMemberBaseBase609Double-Checked Locking
HasMemberBaseBase613Insufficient Session Expiration
HasMemberBaseBase618Exposed Unsafe ActiveX Method
HasMemberBaseBase619Dangling Database Cursor ('Cursor Injection')
HasMemberBaseBase621Variable Extraction Error
HasMemberBaseBase624Executable Regular Expression Error
HasMemberBaseBase625Permissive Regular Expression
HasMemberBaseBase627Dynamic Variable Evaluation
HasMemberBaseBase628Function Call with Incorrectly Specified Arguments
HasMemberBaseBase639Authorization Bypass Through User-Controlled Key
HasMemberBaseBase640Weak Password Recovery Mechanism for Forgotten Password
HasMemberBaseBase641Improper Restriction of Names for Files and Other Resources
HasMemberBaseBase643Improper Neutralization of Data within XPath Expressions ('XPath Injection')
HasMemberBaseBase645Overly Restrictive Account Lockout Mechanism
HasMemberBaseBase648Incorrect Use of Privileged APIs
HasMemberBaseBase649Reliance on Obfuscation or Encryption of Security-Relevant Inputs without Integrity Checking
HasMemberBaseBase652Improper Neutralization of Data within XQuery Expressions ('XQuery Injection')
HasMemberBaseBase653Insufficient Compartmentalization
HasMemberBaseBase654Reliance on a Single Factor in a Security Decision
HasMemberBaseBase655Insufficient Psychological Acceptability
HasMemberBaseBase656Reliance on Security Through Obscurity
HasMemberBaseBase662Improper Synchronization
HasMemberBaseBase663Use of a Non-reentrant Function in a Concurrent Context
HasMemberBaseBase666Operation on Resource in Wrong Phase of Lifetime
HasMemberBaseBase667Improper Locking
HasMemberBaseBase672Operation on a Resource after Expiration or Release
HasMemberBaseBase674Uncontrolled Recursion
HasMemberBaseBase676Use of Potentially Dangerous Function
HasMemberBaseBase694Use of Multiple Resources with Duplicate Identifier
HasMemberBaseBase695Use of Low-Level Functionality
HasMemberBaseBase698Execution After Redirect (EAR)
HasMemberBaseBase708Incorrect Ownership Assignment
HasMemberBaseBase733Compiler Optimization Removal or Modification of Security-critical Code
HasMemberBaseBase749Exposed Dangerous Method or Function
HasMemberBaseBase759Use of a One-Way Hash without a Salt
HasMemberBaseBase760Use of a One-Way Hash with a Predictable Salt
HasMemberBaseBase763Release of Invalid Pointer or Reference
HasMemberBaseBase769Uncontrolled File Descriptor Consumption
HasMemberBaseBase770Allocation of Resources Without Limits or Throttling
HasMemberBaseBase771Missing Reference to Active Allocated Resource
HasMemberBaseBase772Missing Release of Resource after Effective Lifetime
HasMemberBaseBase778Insufficient Logging
HasMemberBaseBase779Logging of Excessive Data
HasMemberBaseBase786Access of Memory Location Before Start of Buffer
HasMemberBaseBase787Out-of-bounds Write
HasMemberBaseBase788Access of Memory Location After End of Buffer
HasMemberBaseBase791Incomplete Filtering of Special Elements
HasMemberBaseBase795Only Filtering Special Elements at a Specified Location
HasMemberBaseBase798Use of Hard-coded Credentials
HasMemberBaseBase804Guessable CAPTCHA
HasMemberBaseBase805Buffer Access with Incorrect Length Value
HasMemberBaseBase807Reliance on Untrusted Inputs in a Security Decision
HasMemberBaseBase820Missing Synchronization
HasMemberBaseBase821Incorrect Synchronization
HasMemberBaseBase822Untrusted Pointer Dereference
HasMemberBaseBase823Use of Out-of-range Pointer Offset
HasMemberBaseBase824Access of Uninitialized Pointer
HasMemberBaseBase825Expired Pointer Dereference
HasMemberBaseBase826Premature Release of Resource During Expected Lifetime
HasMemberBaseBase827Improper Control of Document Type Definition
HasMemberBaseBase828Signal Handler with Functionality that is not Asynchronous-Safe
HasMemberBaseBase830Inclusion of Web Functionality from an Untrusted Source
HasMemberBaseBase831Signal Handler Function Associated with Multiple Signals
HasMemberBaseBase832Unlock of a Resource that is not Locked
HasMemberBaseBase833Deadlock
HasMemberBaseBase834Excessive Iteration
HasMemberBaseBase835Loop with Unreachable Exit Condition ('Infinite Loop')
HasMemberBaseBase836Use of Password Hash Instead of Password for Authentication
HasMemberBaseBase837Improper Enforcement of a Single, Unique Action
HasMemberBaseBase838Inappropriate Encoding for Output Context
HasMemberBaseBase839Numeric Range Comparison Without Minimum Check
HasMemberBaseBase841Improper Enforcement of Behavioral Workflow
HasMemberBaseBase842Placement of User into Incorrect Group
HasMemberBaseBase843Access of Resource Using Incompatible Type ('Type Confusion')
HasMemberBaseBase908Use of Uninitialized Resource
HasMemberBaseBase909Missing Initialization of Resource
HasMemberBaseBase910Use of Expired File Descriptor
HasMemberBaseBase911Improper Update of Reference Count
HasMemberBaseBase914Improper Control of Dynamically-Identified Variables
HasMemberBaseBase915Improperly Controlled Modification of Dynamically-Determined Object Attributes
HasMemberBaseBase916Use of Password Hash With Insufficient Computational Effort
HasMemberBaseBase917Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
HasMemberBaseBase918Server-Side Request Forgery (SSRF)
HasMemberBaseBase920Improper Restriction of Power Consumption
HasMemberBaseBase921Storage of Sensitive Data in a Mechanism without Access Control
HasMemberBaseBase939Improper Authorization in Handler for Custom URL Scheme
HasMemberBaseBase940Improper Verification of Source of a Communication Channel
HasMemberBaseBase941Incorrectly Specified Destination in a Communication Channel
HasMemberBaseBase1007Insufficient Visual Distinction of Homoglyphs Presented to User
HasMemberBaseBase1021Improper Restriction of Rendered UI Layers or Frames
+ Content History
Modifications
Modification DateModifierOrganizationSource
2008-09-08CWE Content TeamMITRE
updated View_Filter, View_Structure
+ View Metrics
CWEs in this viewTotal CWEs
Total328out of982
Weaknesses328out of 714
Categories0out of 237
Views0out of 31

View Components

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CWE-36: Absolute Path Traversal

Weakness ID: 36
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The software uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize absolute path sequences such as "/abs/path" that can resolve to a location that is outside of that directory.
+ Extended Description
This allows attackers to traverse the file system to access files or directories that are outside of the restricted directory.
+ Relationships

The table(s) below 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.

+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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 software from working at all and in the case of a protection mechanisms such as authentication, it has the potential to lockout every user of the software.
+ Demonstrative Examples

Example 1

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

(bad)
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 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 2

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)
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)
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
{...}

}
...

}

As with the previous example this code does not perform a check on the type of the file being uploaded. 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-22, CWE-23). 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.

+ Observed Examples
ReferenceDescription
Multiple FTP clients write arbitrary files via absolute paths in server responses
ZIP file extractor allows full path
Path traversal using absolute pathname
Path traversal using absolute pathname
Path traversal using absolute pathname
Arbitrary files may be overwritten via compressed attachments that specify absolute path names for the decompressed output.
Mail client allows remote attackers to overwrite arbitrary files via an e-mail message containing a uuencoded attachment that specifies the full pathname for the file to be modified.
Remote attackers can read arbitrary files via a full pathname to the target file in config parameter.
Remote attackers can read arbitrary files via an absolute pathname.
Remote attackers can read arbitrary files by specifying the drive letter in the requested URL.
FTP server allows remote attackers to list arbitrary directories by using the "ls" command and including the drive letter name (e.g. C:) in the requested pathname.
FTP server allows remote attackers to list the contents of arbitrary drives via a ls command that includes the drive letter as an argument.
Server allows remote attackers to browse arbitrary directories via a full pathname in the arguments to certain dynamic pages.
Remote attackers can read arbitrary files via an HTTP request whose argument is a filename of the form "C:" (Drive letter), "//absolute/path", or ".." .
FTP server read/access arbitrary files using "C:\" filenames
FTP server allows a remote attacker to retrieve privileged web server system information by specifying arbitrary paths in the UNC format (\\computername\sharename).
+ Memberships
This 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
MemberOfViewView884CWE Cross-section
MemberOfCategoryCategory981SFP Secondary Cluster: Path Traversal
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERAbsolute Path Traversal
Software Fault PatternsSFP16Path Traversal
+ References
[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.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Sean EidemillerCigital
added/updated demonstrative examples
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2008-10-14CWE Content TeamMITRE
updated Description
2010-02-16CWE Content TeamMITRE
updated Demonstrative_Examples
2010-06-21CWE Content TeamMITRE
updated Demonstrative_Examples, Description
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Observed_Examples, References, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2017-01-19CWE Content TeamMITRE
updated Related_Attack_Patterns
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms

CWE-349: Acceptance of Extraneous Untrusted Data With Trusted Data

Weakness ID: 349
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The software, when processing trusted data, accepts any untrusted data that is also included with the trusted data, treating the untrusted data as if it were trusted.
+ Relationships

The table(s) below 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
ChildOfClassClass345Insufficient Verification of Data Authenticity
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory1019Validate Inputs
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
ChildOfClassClass345Insufficient Verification of Data Authenticity
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and DesignOMISSION: This weakness is caused by missing a security tactic during the architecture and design phase.
Implementation
+ Applicable Platforms
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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
Integrity

Technical Impact: Bypass Protection Mechanism; Modify Application Data

An attacker could package untrusted data with trusted data to bypass protection mechanisms to gain access to and possibly modify sensitive data.
+ Observed Examples
ReferenceDescription
Does not verify that trusted entity is authoritative for all entities in its response.
+ Memberships
This 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.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERUntrusted Data Appended with Trusted Data
CERT Java Secure CodingENV01-JPlace all security-sensitive code in a single JAR and sign and seal it
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Modes_of_Introduction, Relationships
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Untrusted Data Appended with Trusted Data

CWE-788: Access of Memory Location After End of Buffer

Weakness ID: 788
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The software reads or writes to a buffer using an index or pointer that references a memory location after the end of the buffer.
+ Extended Description
This typically occurs when a pointer or its index is decremented to a position before the buffer; when pointer arithmetic results in a position before the buffer; or when a negative index is used, which generates a position before the buffer.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Development Concepts" (CWE-699)
+ Common Consequences

The table below 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

For an out-of-bounds read, the attacker may have access to sensitive information. If the sensitive information contains system details, such as the current buffers position in memory, this knowledge can be used to craft further attacks, possibly with more severe consequences.
Integrity
Availability

Technical Impact: Modify Memory; DoS: Crash, Exit, or Restart

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.
Integrity

Technical Impact: Modify Memory; Execute Unauthorized Code or Commands

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 redirect 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.
+ 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)
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 we 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

In the following example, it is possible to request that memcpy move a much larger segment of memory than assumed:

(bad)
Example Language:
int returnChunkSize(void *) {
/* if chunk info is valid, return the size of usable memory,
* else, return -1 to indicate an error
*/
...

}
int main() {
...
memcpy(destBuf, srcBuf, (returnChunkSize(destBuf)-1));
...

}

If returnChunkSize() happens to encounter an error it will return -1. Notice that the return value is not checked before the memcpy operation (CWE-252), so -1 can be passed as the size argument to memcpy() (CWE-805). Because memcpy() assumes that the value is unsigned, it will be interpreted as MAXINT-1 (CWE-195), and therefore will copy far more memory than is likely available to the destination buffer (CWE-787, CWE-788).

Example 3

This example applies an encoding procedure to an input string and stores it into a buffer.

(bad)
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 4

In the following C/C++ example the method processMessageFromSocket() will get a message from a socket, placed into a buffer, and will parse the contents of the buffer into a structure that contains the message length and the message body. A for loop is used to copy the message body into a local character string which will be passed to another method for processing.

(bad)
Example Language:
int processMessageFromSocket(int socket) {
int success;

char buffer[BUFFER_SIZE];
char message[MESSAGE_SIZE];
// get message from socket and store into buffer
//Ignoring possibliity that buffer > BUFFER_SIZE

if (getMessage(socket, buffer, BUFFER_SIZE) > 0) {
// place contents of the buffer into message structure

ExMessage *msg = recastBuffer(buffer);
// copy message body into string for processing

int index;
for (index = 0; index < msg->msgLength; index++) {
message[index] = msg->msgBody[index];

}
message[index] = '\0';
// process message

success = processMessage(message);

}
return success;

}

However, the message length variable from the structure is used as the condition for ending the for loop without validating that the message length variable accurately reflects the length of message body. This can result in a buffer over read by reading from memory beyond the bounds of the buffer if the message length variable indicates a length that is longer than the size of a message body (CWE-130).

+ Observed Examples
ReferenceDescription
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
attacker-controlled array index leads to code execution
OS kernel trusts userland-supplied length value, allowing reading of sensitive information
Chain: integer signedness error (CWE-195) passes signed comparison, leading to heap overflow (CWE-122)
+ Memberships
This 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
MemberOfViewView884CWE Cross-section
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
2009-10-21CWE Content TeamMITRE
Modifications
Modification DateModifierOrganizationSource
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Observed_Examples, Relationships
2013-02-21CWE Content TeamMITRE
updated Demonstrative_Examples
2014-06-23CWE Content TeamMITRE
updated Demonstrative_Examples
2015-12-07CWE Content TeamMITRE
updated Description
2017-05-03CWE Content TeamMITRE
updated Description
2017-11-08CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Observed_Examples

CWE-786: Access of Memory Location Before Start of Buffer

Weakness ID: 786
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The software reads or writes to a buffer using an index or pointer that references a memory location prior to the beginning of the buffer.
+ Extended Description
This typically occurs when a pointer or its index is decremented to a position before the buffer, when pointer arithmetic results in a position before the beginning of the valid memory location, or when a negative index is used.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Development Concepts" (CWE-699)
+ Common Consequences

The table below 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

For an out-of-bounds read, the attacker may have access to sensitive information. If the sensitive information contains system details, such as the current buffers position in memory, this knowledge can be used to craft further attacks, possibly with more severe consequences.
Integrity
Availability

Technical Impact: Modify Memory; DoS: Crash, Exit, or Restart

Out of bounds memory access will very likely result in the corruption of relevant memory, and perhaps instructions, possibly leading to a crash.
Integrity

Technical Impact: Modify Memory; Execute Unauthorized Code or Commands

If the corrupted memory can be effectively controlled, it may be possible to execute arbitrary code. If the corrupted memory is data rather than instructions, the system will continue to function with improper changes, possibly in violation of an implicit or explicit policy.
+ Demonstrative Examples

Example 1

In the following C/C++ example, a utility function is used to trim trailing whitespace from a character string. The function copies the input string to a local character string and uses a while statement to remove the trailing whitespace by moving backward through the string and overwriting whitespace with a NUL character.

(bad)
Example Language:
char* trimTrailingWhitespace(char *strMessage, int length) {
char *retMessage;
char *message = malloc(sizeof(char)*(length+1));
// copy input string to a temporary string

char message[length+1];
int index;
for (index = 0; index < length; index++) {
message[index] = strMessage[index];

}
message[index] = '\0';
// trim trailing whitespace

int len = index-1;
while (isspace(message[len])) {
message[len] = '\0';
len--;

}
// return string without trailing whitespace

retMessage = message;
return retMessage;

}

However, this function can cause a buffer underwrite if the input character string contains all whitespace. On some systems the while statement will move backwards past the beginning of a character string and will call the isspace() function on an address outside of the bounds of the local buffer.

Example 2

The following example asks a user for an offset into an array to select an item.

(bad)
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 3

The following is an example of code that may result in a buffer underwrite, if find() returns a negative value to indicate that ch is not found in srcBuf:

(bad)
Example Language:
int main() {
...
strncpy(destBuf, &srcBuf[find(srcBuf, ch)], 1024);
...

}

If the index to srcBuf is somehow under user control, this is an arbitrary write-what-where condition.

+ Observed Examples
ReferenceDescription
Unchecked length of SSLv2 challenge value leads to buffer underflow.
Buffer underflow from a small size value with a large buffer (length parameter inconsistency, CWE-130)
Buffer underflow from an all-whitespace string, which causes a counter to be decremented before the buffer while looking for a non-whitespace character.
Buffer underflow resultant from encoded data that triggers an integer overflow.
Product sets an incorrect buffer size limit, leading to "off-by-two" buffer underflow.
Negative value is used in a memcpy() operation, leading to buffer underflow.
Buffer underflow due to mishandled special characters
+ Memberships
This 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
MemberOfViewView884CWE Cross-section
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CERT C Secure CodingARR30-CCWE More SpecificDo not form or use out-of-bounds pointers or array subscripts
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
2009-10-21CWE Content TeamMITRE
Modifications
Modification DateModifierOrganizationSource
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Observed_Examples, Relationships
2017-11-08CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Taxonomy_Mappings

CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')

Weakness ID: 843
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The program allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.
+ Extended Description

When the program accesses the resource using an incompatible type, this could trigger logical errors because the resource does not have expected properties. In languages without memory safety, such as C and C++, type confusion can lead to out-of-bounds memory access.

While this weakness is frequently associated with unions when parsing data with many different embedded object types in C, it can be present in any application that can interpret the same variable or memory location in multiple ways.

This weakness is not unique to C and C++. For example, errors in PHP applications can be triggered by providing array parameters when scalars are expected, or vice versa. Languages such as Perl, which perform automatic conversion of a variable of one type when it is accessed as if it were another type, can also contain these issues.

+ Relationships

The table(s) below 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)
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
ChildOfClassClass704Incorrect Type Conversion or Cast
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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: (Undetermined Prevalence)

C++: (Undetermined Prevalence)

+ Alternate Terms
Object Type Confusion
+ Demonstrative Examples

Example 1

The following code uses a union to support the representation of different types of messages. It formats messages differently, depending on their type.

(bad)
Example Language:
#define NAME_TYPE 1
#define ID_TYPE 2

struct MessageBuffer
{
int msgType;
union {
char *name;
int nameID;

};

};


int main (int argc, char **argv) {
struct MessageBuffer buf;
char *defaultMessage = "Hello World";

buf.msgType = NAME_TYPE;
buf.name = defaultMessage;
printf("Pointer of buf.name is %p\n", buf.name);
/* This particular value for nameID is used to make the code architecture-independent. If coming from untrusted input, it could be any value. */

buf.nameID = (int)(defaultMessage + 1);
printf("Pointer of buf.name is now %p\n", buf.name);
if (buf.msgType == NAME_TYPE) {
printf("Message: %s\n", buf.name);

}
else {
printf("Message: Use ID %d\n", buf.nameID);

}

}

The code intends to process the message as a NAME_TYPE, and sets the default message to "Hello World." However, since both buf.name and buf.nameID are part of the same union, they can act as aliases for the same memory location, depending on memory layout after compilation.

As a result, modification of buf.nameID - an int - can effectively modify the pointer that is stored in buf.name - a string.

Execution of the program might generate output such as:

Pointer of name is 10830
Pointer of name is now 10831
Message: ello World

Notice how the pointer for buf.name was changed, even though buf.name was not explicitly modified.

In this case, the first "H" character of the message is omitted. However, if an attacker is able to fully control the value of buf.nameID, then buf.name could contain an arbitrary pointer, leading to out-of-bounds reads or writes.

Example 2

The following PHP code accepts a value, adds 5, and prints the sum.

(bad)
Example Language: PHP 
$value = $_GET['value'];
$sum = $value + 5;
echo "value parameter is '$value'<p>";
echo "SUM is $sum";

When called with the following query string:

value=123

the program calculates the sum and prints out:

SUM is 128

However, the attacker could supply a query string such as:

value[]=123

The "[]" array syntax causes $value to be treated as an array type, which then generates a fatal error when calculating $sum:

Fatal error: Unsupported operand types in program.php on line 2

Example 3

The following Perl code is intended to look up the privileges for user ID's between 0 and 3, by performing an access of the $UserPrivilegeArray reference. It is expected that only userID 3 is an admin (since this is listed in the third element of the array).

(bad)
Example Language: Perl 
my $UserPrivilegeArray = ["user", "user", "admin", "user"];

my $userID = get_current_user_ID();

if ($UserPrivilegeArray eq "user") {
print "Regular user!\n";

}
else {
print "Admin!\n";

}

print "\$UserPrivilegeArray = $UserPrivilegeArray\n";

In this case, the programmer intended to use "$UserPrivilegeArray->{$userID}" to access the proper position in the array. But because the subscript was omitted, the "user" string was compared to the scalar representation of the $UserPrivilegeArray reference, which might be of the form "ARRAY(0x229e8)" or similar.

Since the logic also "fails open" (CWE-636), the result of this bug is that all users are assigned administrator privileges.

While this is a forced example, it demonstrates how type confusion can have security consequences, even in memory-safe languages.

+ Observed Examples
ReferenceDescription
Type confusion in CSS sequence leads to out-of-bounds read.
Size inconsistency allows code execution, first discovered when it was actively exploited in-the-wild.
Improperly-parsed file containing records of different types leads to code execution when a memory location is interpreted as a different object than intended.
+ Notes

Applicable Platform

This weakness is possible in any type-unsafe programming language.

Research Gap

Type confusion weaknesses have received some attention by applied researchers and major software vendors for C and C++ code. Some publicly-reported vulnerabilities probably have type confusion as a root-cause weakness, but these may be described as "memory corruption" instead. This weakness seems likely to gain prominence in upcoming years.

For other languages, there are very few public reports of type confusion weaknesses. These are probably under-studied. Since many programs rely directly or indirectly on loose typing, a potential "type confusion" behavior might be intentional, possibly requiring more manual analysis.

+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CERT C Secure CodingEXP39-CExactDo not access a variable through a pointer of an incompatible type
+ References
[REF-811] Mark Dowd, Ryan Smith and David Dewey. "Attacking Interoperability". "Type Confusion Vulnerabilities," page 59. 2009. <http://www.azimuthsecurity.com/resources/bh2009_dowd_smith_dewey.pdf>.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 7, "Type Confusion", Page 319.. 1st Edition. Addison Wesley. 2006.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
2011-05-15CWE Content TeamMITRE
Modifications
Modification DateModifierOrganizationSource
2012-05-11CWE Content TeamMITRE
updated References
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Taxonomy_Mappings

CWE-824: Access of Uninitialized Pointer

Weakness ID: 824
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The program accesses or uses a pointer that has not been initialized.
+ Extended Description

If the pointer contains an uninitialized value, then the value might not point to a valid memory location. This could cause the program to read from or write to unexpected memory locations, leading to a denial of service. If the uninitialized pointer is used as a function call, then arbitrary functions could be invoked. If an attacker can influence the portion of uninitialized memory that is contained in the pointer, this weakness could be leveraged to execute code or perform other attacks.

Depending on memory layout, associated memory management behaviors, and program operation, the attacker might be able to influence the contents of the uninitialized pointer, thus gaining more fine-grained control of the memory location to be accessed.

+ Relationships

The table(s) below 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)
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
+ Relevant to the view "Development Concepts" (CWE-699)
+ Common Consequences

The table below 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

If the uninitialized pointer is used in a read operation, an attacker might be able to read sensitive portions of memory.
Availability

Technical Impact: DoS: Crash, Exit, or Restart

If the uninitialized pointer references a memory location that is not accessible to the program, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity
Confidentiality
Availability

Technical Impact: Execute Unauthorized Code or Commands

If the uninitialized pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
+ Observed Examples
ReferenceDescription
chain: unchecked return value (CWE-252) leads to free of invalid, uninitialized pointer (CWE-824).
Pointer in structure is not initialized, leading to NULL pointer dereference (CWE-476) and system crash.
Free of an uninitialized pointer.
Improper handling of invalid signatures leads to free of invalid pointer.
Invalid encoding triggers free of uninitialized pointer.
Crafted PNG image leads to free of uninitialized pointer.
Crafted GIF image leads to free of uninitialized pointer.
Access of uninitialized pointer might lead to code execution.
Step-based manipulation: invocation of debugging function before the primary initialization function leads to access of an uninitialized pointer and code execution.
Unchecked return values can lead to a write to an uninitialized pointer.
zero-length input leads to free of uninitialized pointer.
Crafted font leads to uninitialized function pointer.
Uninitialized function pointer in freed memory is invoked
LDAP server mishandles malformed BER queries, leading to free of uninitialized memory
Firewall can crash with certain ICMP packets that trigger access of an uninitialized pointer.
LDAP server does not initialize members of structs, which leads to free of uninitialized pointer if an LDAP request fails.
+ Notes

Maintenance

There are close relationships between incorrect pointer dereferences and other weaknesses related to buffer operations. There may not be sufficient community agreement regarding these relationships. Further study is needed to determine when these relationships are chains, composites, perspective/layering, or other types of relationships. As of September 2010, most of the relationships are being captured as chains.

Research Gap

Under-studied and probably under-reported as of September 2010. This weakness has been reported in high-visibility software, but applied vulnerability researchers have only been investigating it since approximately 2008, and there are only a few public reports. Few reports identify weaknesses at such a low level, which makes it more difficult to find and study real-world code examples.

Terminology

Many weaknesses related to pointer dereferences fall under the general term of "memory corruption" or "memory safety." As of September 2010, there is no commonly-used terminology that covers the lower-level variants.
+ References
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 7, "Variable Initialization", Page 312.. 1st Edition. Addison Wesley. 2006.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
2010-09-22CWE Content TeamMITRE
Modifications
Modification DateModifierOrganizationSource
2012-05-11CWE Content TeamMITRE
updated References
2015-12-07CWE Content TeamMITRE
updated Relationships

CWE-464: Addition of Data Structure Sentinel

Weakness ID: 464
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The accidental addition of a data-structure sentinel can cause serious programming logic problems.
+ Extended Description
Data-structure sentinels are often used to mark the structure of data. A common example of this is the null character at the end of strings or a special sentinel to mark the end of a linked list. It is dangerous to allow this type of control data to be easily accessible. Therefore, it is important to protect from the addition or modification of sentinels.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory461Data Structure Issues
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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: (Undetermined Prevalence)

C++: (Undetermined Prevalence)

+ Common Consequences

The table below 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

Technical Impact: Modify Application Data

Generally this error will cause the data structure to not work properly by truncating the data.
+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

The following example assigns some character values to a list of characters and prints them each individually, and then as a string. The third character value is intended to be an integer taken from user input and converted to an int.

(bad)
Example Language:
char *foo;
foo=malloc(sizeof(char)*5);
foo[0]='a';
foo[1]='a';
foo[2]=atoi(getc(stdin));
foo[3]='c';
foo[4]='\0'
printf("%c %c %c %c %c \n",foo[0],foo[1],foo[2],foo[3],foo[4]);
printf("%s\n",foo);

The first print statement will print each character separated by a space. However, if a non-integer is read from stdin by getc, then atoi will not make a conversion and return 0. When foo is printed as a string, the 0 at character foo[2] will act as a NULL terminator and foo[3] will never be printed.

+ Potential Mitigations

Phases: Implementation; Architecture and Design

Encapsulate the user from interacting with data sentinels. Validate user input to verify that sentinels are not present.

Phase: Implementation

Proper error checking can reduce the risk of inadvertently introducing sentinel values into data. For example, if a parsing function fails or encounters an error, it might return a value that is the same as the sentinel.

Phase: Architecture and Design

Use an abstraction library to abstract away risky APIs. This is not a complete solution.

Phase: Operation

Use OS-level preventative functionality. This is not a complete solution.
+ Memberships
This 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.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CLASPAddition of data-structure sentinel
CERT C Secure CodingSTR03-CDo not inadvertently truncate a null-terminated byte string
CERT C Secure CodingSTR06-CDo not assume that strtok() leaves the parse string unchanged
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
CLASP
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-07-27CWE Content TeamMITRE
updated Demonstrative_Examples, Description, Other_Notes, Potential_Mitigations, Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-06-27CWE Content TeamMITRE
updated Common_Consequences
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Demonstrative_Examples, Likelihood_of_Exploit, Taxonomy_Mappings
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Addition of Data-structure Sentinel

CWE-407: Algorithmic Complexity

Weakness ID: 407
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
+ Relevant to the view "Development Concepts" (CWE-699)
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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)

The typical consequence is CPU consumption, but memory consumption and consumption of other resources can also occur.
+ Likelihood Of Exploit
Low
+ Observed Examples
ReferenceDescription
CPU consumption via inputs that cause many hash table collisions.
CPU consumption via inputs that cause many hash table collisions.
Product performs unnecessary processing before dropping an invalid packet.
CPU and memory consumption using many wildcards.
Product allows attackers to cause multiple copies of a program to be loaded more quickly than the program can detect that other copies are running, then exit. This type of error should probably have its own category, where teardown takes more time than initialization.
Network monitoring system allows remote attackers to cause a denial of service (CPU consumption and detection outage) via crafted network traffic, aka a "backtracking attack."
Wiki allows remote attackers to cause a denial of service (CPU consumption) by performing a diff between large, crafted pages that trigger the worst case algorithmic complexity.
Wiki allows remote attackers to cause a denial of service (CPU consumption) by performing a diff between large, crafted pages that trigger the worst case algorithmic complexity.
OS allows attackers to cause a denial of service (CPU consumption) via crafted Gregorian dates.
Memory leak by performing actions faster than the software can clear them.
+ Functional Areas
  • Cryptography
+ Memberships
This 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
MemberOfViewView884CWE Cross-section
MemberOfCategoryCategory977SFP Secondary Cluster: Design
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERAlgorithmic Complexity
+ References
[REF-395] Crosby and Wallach. "Algorithmic Complexity Attacks". <http://www.cs.rice.edu/~scrosby/hash/CrosbyWallach_UsenixSec2003/index.html>.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
2009-07-27CWE Content TeamMITRE
updated Functional_Areas, Other_Notes
2009-10-29CWE Content TeamMITRE
updated Common_Consequences
2009-12-28CWE Content TeamMITRE
updated Applicable_Platforms, Likelihood_of_Exploit
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Observed_Examples, Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Likelihood_of_Exploit

CWE-770: Allocation of Resources Without Limits or Throttling

Weakness ID: 770
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The software allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on how many resources can be allocated, in violation of the intended security policy for that actor.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory1011Authorize Actors
+ Relevant to the view "Development Concepts" (CWE-699)
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and DesignOMISSION: This weakness is caused by missing a security tactic during the architecture and design phase.
Implementation
Operation
System Configuration
+ Applicable Platforms
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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 allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource.
+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

This code allocates a socket and forks each time it receives a new connection.

(bad)
Example Language:
sock=socket(AF_INET, SOCK_STREAM, 0);
while (1) {
newsock=accept(sock, ...);
printf("A connection has been accepted\n");
pid = fork();

}

The program does not track how many connections have been made, and it does not limit the number of connections. Because forking is a relatively expensive operation, an attacker would be able to cause the system to run out of CPU, processes, or memory by making a large number of connections. Alternatively, an attacker could consume all available connections, preventing others from accessing the system remotely.

Example 2

In the following example a server socket connection is used to accept a request to store data on the local file system using a specified filename. The method openSocketConnection establishes a server socket to accept requests from a client. When a client establishes a connection to this service the getNextMessage method is first used to retrieve from the socket the name of the file to store the data, the openFileToWrite method will validate the filename and open a file to write to on the local file system. The getNextMessage is then used within a while loop to continuously read data from the socket and output the data to the file until there is no longer any data from the socket.

(bad)
Example Language:
int writeDataFromSocketToFile(char *host, int port)
{

char filename[FILENAME_SIZE];
char buffer[BUFFER_SIZE];
int socket = openSocketConnection(host, port);

if (socket < 0) {
printf("Unable to open socket connection");
return(FAIL);

}
if (getNextMessage(socket, filename, FILENAME_SIZE) > 0) {
if (openFileToWrite(filename) > 0) {
while (getNextMessage(socket, buffer, BUFFER_SIZE) > 0){
if (!(writeToFile(buffer) > 0))
break;

}

}
closeFile();

}
closeSocket(socket);

}

This example creates a situation where data can be dumped to a file on the local file system without any limits on the size of the file. This could potentially exhaust file or disk resources and/or limit other clients' ability to access the service.

Example 3

In the following example, the processMessage method receives a two dimensional character array containing the message to be processed. The two-dimensional character array contains the length of the message in the first character array and the message body in the second character array. The getMessageLength method retrieves the integer value of the length from the first character array. After validating that the message length is greater than zero, the body character array pointer points to the start of the second character array of the two-dimensional character array and memory is allocated for the new body character array.

(bad)
Example Language:
/* process message accepts a two-dimensional character array of the form [length][body] containing the message to be processed */
int processMessage(char **message)
{
char *body;

int length = getMessageLength(message[0]);

if (length > 0) {
body = &message[1][0];
processMessageBody(body);
return(SUCCESS);

}
else {
printf("Unable to process message; invalid message length");
return(FAIL);

}

}

This example creates a situation where the length of the body character array can be very large and will consume excessive memory, exhausting system resources. This can be avoided by restricting the length of the second character array with a maximum length check

Also, consider changing the type from 'int' to 'unsigned int', so that you are always guaranteed that the number is positive. This might not be possible if the protocol specifically requires allowing negative values, or if you cannot control the return value from getMessageLength(), but it could simplify the check to ensure the input is positive, and eliminate other errors such as signed-to-unsigned conversion errors (CWE-195) that may occur elsewhere in the code.

(good)
Example Language:
unsigned int length = getMessageLength(message[0]);
if ((length > 0) && (length < MAX_LENGTH)) {...}

Example 4

In the following example, a server object creates a server socket and accepts client connections to the socket. For every client connection to the socket a separate thread object is generated using the ClientSocketThread class that handles request made by the client through the socket.

(bad)
Example Language: Java 
public void acceptConnections() {
try {
ServerSocket serverSocket = new ServerSocket(SERVER_PORT);
int counter = 0;
boolean hasConnections = true;
while (hasConnections) {
Socket client = serverSocket.accept();
Thread t = new Thread(new ClientSocketThread(client));
t.setName(client.getInetAddress().getHostName() + ":" + counter++);
t.start();

}
serverSocket.close();


} catch (IOException ex) {...}

}

In this example there is no limit to the number of client connections and client threads that are created. Allowing an unlimited number of client connections and threads could potentially overwhelm the system and system resources.

The server should limit the number of client connections and the client threads that are created. This can be easily done by creating a thread pool object that limits the number of threads that are generated.

(good)
Example Language: Java 
public static final int SERVER_PORT = 4444;
public static final int MAX_CONNECTIONS = 10;
...

public void acceptConnections() {
try {
ServerSocket serverSocket = new ServerSocket(SERVER_PORT);
int counter = 0;
boolean hasConnections = true;
while (hasConnections) {
hasConnections = checkForMoreConnections();
Socket client = serverSocket.accept();
Thread t = new Thread(new ClientSocketThread(client));
t.setName(client.getInetAddress().getHostName() + ":" + counter++);
ExecutorService pool = Executors.newFixedThreadPool(MAX_CONNECTIONS);
pool.execute(t);

}
serverSocket.close();


} catch (IOException ex) {...}

}

Example 5

An unnamed web site allowed a user to purchase tickets for an event. A menu option allowed the user to purchase up to 10 tickets, but the back end did not restrict the actual number of tickets that could be purchased.

Example 5 References:

[REF-667] Rafal Los. "Real-Life Example of a 'Business Logic Defect' (Screen Shots!)". 2011. <http://h30501.www3.hp.com/t5/Following-the-White-Rabbit-A/Real-Life-Example-of-a-Business-Logic-Defect-Screen-Shots/ba-p/22581>.
+ Observed Examples
ReferenceDescription
Language interpreter does not restrict the number of temporary files being created when handling a MIME request with a large number of parts..
Driver does not use a maximum width when invoking sscanf style functions, causing stack consumption.
Large integer value for a length property in an object causes a large amount of memory allocation.
Product allows exhaustion of file descriptors when processing a large number of TCP packets.
Communication product allows memory consumption with a large number of SIP requests, which cause many sessions to be created.
Product allows attackers to cause a denial of service via a large number of directives, each of which opens a separate window.
CMS does not restrict the number of searches that can occur simultaneously, leading to resource exhaustion.
+ Potential Mitigations

Phase: Requirements

Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.

Phase: Architecture and Design

Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.

Phase: Architecture and Design

Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place, and it will help the administrator to identify who is committing the abuse. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a whitelist 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 (i.e., do not rely on a blacklist). A blacklist 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, blacklists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
This will only be applicable to cases where user input can influence the size or frequency of resource allocations.

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

Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, typically by using increasing time delays uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution can be difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply requires more resources on the part of the attacker.

Phase: Architecture and Design

Ensure that protocols have specific limits of scale placed on them.

Phases: Architecture and Design; Implementation

If the program must fail, ensure that it fails gracefully (fails closed). There may be a temptation to simply let the program fail poorly in cases such as low memory conditions, but an attacker may be able to assert control before the software has fully exited. Alternately, an uncontrolled failure could cause cascading problems with other downstream components; for example, the program could send a signal to a downstream process so the process immediately knows that a problem has occurred and has a better chance of recovery. Ensure that all failures in resource allocation place the system into a safe posture.

Phases: Operation; Architecture and Design

Strategy: Resource Limitation

Use resource-limiting settings provided by the operating system or environment. For example, when managing system resources in POSIX, setrlimit() can be used to set limits for certain types of resources, and getrlimit() can determine how many resources are available. However, these functions are not available on all operating systems. When the current levels get close to the maximum that is defined for the application (see CWE-770), then limit the allocation of further resources to privileged users; alternately, begin releasing resources for less-privileged users. While this mitigation may protect the system from attack, it will not necessarily stop attackers from adversely impacting other users. Ensure that the application performs the appropriate error checks and error handling in case resources become unavailable (CWE-703).
+ Detection Methods

Manual Static Analysis

Manual static analysis can be useful for finding this weakness, but it might not achieve desired code coverage within limited time constraints. If denial-of-service is not considered a significant risk, or if there is strong emphasis on consequences such as code execution, then manual analysis may not focus on this weakness at all.

Fuzzing

While fuzzing is typically geared toward finding low-level implementation bugs, it can inadvertently find uncontrolled resource allocation problems. This can occur when the fuzzer generates a large number of test cases but does not restart the targeted software in between test cases. If an individual test case produces a crash, but it does not do so reliably, then an inability to limit resource allocation may be the cause.

When the allocation is directly affected by numeric inputs, then fuzzing may produce indications of this weakness.

Effectiveness: Opportunistic

Automated Dynamic Analysis

Certain automated dynamic analysis techniques may be effective in producing side effects of uncontrolled resource allocation problems, especially with resources such as processes, memory, and connections. The technique may involve generating a large number of requests to the software within a short time frame. Manual analysis is likely required to interpret the results.

Automated Static Analysis

Specialized configuration or tuning may be required to train automated tools to recognize this weakness.

Automated static analysis typically has limited utility in recognizing unlimited allocation problems, except for the missing release of program-independent system resources such as files, sockets, and processes, or unchecked arguments to memory. For system resources, automated static analysis may be able to detect circumstances in which resources are not released after they have expired, or if too much of a resource is requested at once, as can occur with memory. Automated analysis of configuration files may be able to detect settings that do not specify a maximum value.

Automated static analysis tools will not be appropriate for detecting exhaustion of custom resources, such as an intended security policy in which a bulletin board user is only allowed to make a limited number of posts per day.

+ Memberships
This 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.
+ Notes

Maintenance

"Resource exhaustion" (CWE-400) is currently treated as a weakness, although it is more like a category of weaknesses that all have the same type of consequence. While this entry treats CWE-400 as a parent in view 1000, the relationship is probably more appropriately described as a chain.

Theoretical

Vulnerability theory is largely about how behaviors and resources interact. "Resource exhaustion" can be regarded as either a consequence or an attack, depending on the perspective. This entry is an attempt to reflect one of the underlying weaknesses that enable these attacks (or consequences) to take place.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CERT Java Secure CodingFIO04-JClose resources when they are no longer needed
CERT Java Secure CodingSER12-JAvoid memory and resource leaks during serialization
CERT Java Secure CodingMSC05-JDo not exhaust heap space
+ References
[REF-386] Joao Antunes, Nuno Ferreira Neves and Paulo Verissimo. "Detection and Prediction of Resource-Exhaustion Vulnerabilities". Proceedings of the IEEE International Symposium on Software Reliability Engineering (ISSRE). 2008-11. <http://homepages.di.fc.ul.pt/~nuno/PAPERS/ISSRE08.pdf>.
[REF-387] D.J. Bernstein. "Resource exhaustion". <http://cr.yp.to/docs/resources.html>.
[REF-388] Pascal Meunier. "Resource exhaustion". Secure Programming Educational Material. 2004. <http://homes.cerias.purdue.edu/~pmeunier/secprog/sanitized/class1/6.resource%20exhaustion.ppt>.
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 17, "Protecting Against Denial of Service Attacks" Page 517. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoft.com/mspress/books/toc/5957.aspx>.
[REF-672] Frank Kim. "Top 25 Series - Rank 22 - Allocation of Resources Without Limits or Throttling". SANS Software Security Institute. 2010-03-23. <http://blogs.sans.org/appsecstreetfighter/2010/03/23/top-25-series-rank-22-allocation-of-resources-without-limits-or-throttling/>.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 10, "Resource Limits", Page 574.. 1st Edition. Addison Wesley. 2006.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
2009-05-13CWE Content TeamMITRE
Modifications
Modification DateModifierOrganizationSource
2009-07-27CWE Content TeamMITRE
updated Related_Attack_Patterns
2009-10-29CWE Content TeamMITRE
updated Relationships
2009-12-28CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples, Detection_Factors, Observed_Examples, References, Time_of_Introduction
2010-02-16CWE Content TeamMITRE
updated Common_Consequences, Detection_Factors, Potential_Mitigations, References, Related_Attack_Patterns, Relationships
2010-04-05CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Related_Attack_Patterns
2010-06-21CWE Content TeamMITRE
updated Common_Consequences, Potential_Mitigations, References
2010-09-27CWE Content TeamMITRE
updated Demonstrative_Examples, Potential_Mitigations
2011-03-29CWE Content TeamMITRE
updated Demonstrative_Examples, Detection_Factors, 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 Demonstrative_Examples, References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-02-18CWE Content TeamMITRE
updated Related_Attack_Patterns
2014-06-23CWE Content TeamMITRE
updated Related_Attack_Patterns
2014-07-30CWE Content TeamMITRE
updated Relationships
2015-12-07CWE Content TeamMITRE
updated Related_Attack_Patterns
2017-05-03CWE Content TeamMITRE
updated Related_Attack_Patterns
2017-11-08CWE Content TeamMITRE
updated Demonstrative_Examples, Likelihood_of_Exploit, Modes_of_Introduction, Potential_Mitigations, References, Relationships, Taxonomy_Mappings

CWE-88: Argument Injection or Modification

Weakness ID: 88
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The software does not sufficiently delimit the arguments being passed to a component in another control sphere, allowing alternate arguments to be provided, leading to potentially security-relevant changes.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory1019Validate Inputs
+ Relevant to the view "Development Concepts" (CWE-699)
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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
Other

Technical Impact: Execute Unauthorized Code or Commands; Alter Execution Logic; Read Application Data; Modify Application Data

An attacker could include arguments that allow unintended commands or code to be executed, allow sensitive data to be read or modified or could cause other unintended behavior.
+ Demonstrative Examples

Example 1

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)
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).

+ Observed Examples
ReferenceDescription
Canonical Example
Web browser executes Telnet sessions using command line arguments that are specified by the web site, which could allow remote attackers to execute arbitrary commands.
Web browser allows remote attackers to execute commands by spawning Telnet with a log file option on the command line and writing arbitrary code into an executable file which is later executed.
Argument injection vulnerability in the mail function for PHP may allow attackers to bypass safe mode restrictions and modify command line arguments to the MTA (e.g. sendmail) possibly executing commands.
Help and Support center in windows does not properly validate HCP URLs, which allows remote attackers to execute arbitrary code via quotation marks in an "hcp://" URL.
Mail client does not sufficiently filter parameters of mailto: URLs when using them as arguments to mail executable, which allows remote attackers to execute arbitrary programs.
Web browser doesn't filter "-" when invoking various commands, allowing command-line switches to be specified.
Mail client allows remote attackers to execute arbitrary code via a URI that uses a UNC network share pathname to provide an alternate configuration file.
SSH URI handler for web browser allows remote attackers to execute arbitrary code or conduct port forwarding via the a command line option.
Web browser doesn't filter "-" when invoking various commands, allowing command-line switches to be specified.
Argument injection vulnerability in TellMe 1.2 and earlier allows remote attackers to modify command line arguments for the Whois program and obtain sensitive information via "--" style options in the q_Host parameter.
Beagle before 0.2.5 can produce certain insecure command lines to launch external helper applications while indexing, which allows attackers to execute arbitrary commands. NOTE: it is not immediately clear whether this issue involves argument injection, shell metacharacters, or other issues.
Argument injection vulnerability in Internet Explorer 6 for Windows XP SP2 allows user-assisted remote attackers to modify command line arguments to an invoked mail client via " (double quote) characters in a mailto: scheme handler, as demonstrated by launching Microsoft Outlook with an arbitrary filename as an attachment. NOTE: it is not clear whether this issue is implementation-specific or a problem in the Microsoft API.
Argument injection vulnerability in Mozilla Firefox 1.0.6 allows user-assisted remote attackers to modify command line arguments to an invoked mail client via " (double quote) characters in a mailto: scheme handler, as demonstrated by launching Microsoft Outlook with an arbitrary filename as an attachment. NOTE: it is not clear whether this issue is implementation-specific or a problem in the Microsoft API.
Argument injection vulnerability in Avant Browser 10.1 Build 17 allows user-assisted remote attackers to modify command line arguments to an invoked mail client via " (double quote) characters in a mailto: scheme handler, as demonstrated by launching Microsoft Outlook with an arbitrary filename as an attachment. NOTE: it is not clear whether this issue is implementation-specific or a problem in the Microsoft API.
Argument injection vulnerability in the URI handler in Skype 2.0.*.104 and 2.5.*.0 through 2.5.*.78 for Windows allows remote authorized attackers to download arbitrary files via a URL that contains certain command-line switches.
Argument injection vulnerability in WinSCP 3.8.1 build 328 allows remote attackers to upload or download arbitrary files via encoded spaces and double-quote characters in a scp or sftp URI.
Argument injection vulnerability in the Windows Object Packager (packager.exe) in Microsoft Windows XP SP1 and SP2 and Server 2003 SP1 and earlier allows remote user-assisted attackers to execute arbitrary commands via a crafted file with a "/" (slash) character in the filename of the Command Line property, followed by a valid file extension, which causes the command before the slash to be executed, aka "Object Packager Dialogue Spoofing Vulnerability."
Argument injection vulnerability in HyperAccess 8.4 allows user-assisted remote attackers to execute arbitrary vbscript and commands via the /r option in a telnet:// URI, which is configured to use hawin32.exe.
Argument injection vulnerability in the telnet daemon (in.telnetd) in Solaris 10 and 11 (SunOS 5.10 and 5.11) misinterprets certain client "-f" sequences as valid requests for the login program to skip authentication, which allows remote attackers to log into certain accounts, as demonstrated by the bin account.
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.
+ Potential Mitigations

Phase: Architecture and Design

Strategy: Input Validation

Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, request headers as well as content, URL components, e-mail, files, databases, and any external systems that provide data to the application. Perform input validation at well-defined interfaces.

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a whitelist 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 (i.e., do not rely on a blacklist). A blacklist 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, blacklists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

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 whitelist 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.

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: 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 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.
+ Weakness Ordinalities
OrdinalityDescription
Primary
(where the weakness exists independent of other weaknesses)
+ Affected Resources
  • System Process
+ Memberships
This 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.
+ Notes

Relationship

At one layer of abstraction, this can overlap other weaknesses that have whitespace problems, e.g. injection of javascript into attributes of HTML tags.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERArgument Injection or Modification
CERT C Secure CodingENV03-CSanitize the environment when invoking external programs
CERT C Secure CodingENV33-CImpreciseDo not call system()
CERT C Secure CodingSTR02-CSanitize data passed to complex subsystems
WASC30Mail Command Injection
+ References
[REF-859] Steven Christey. "Argument injection issues". <http://www.securityfocus.com/archive/1/archive/1/460089/100/100/threaded>.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 10, "The Argument Array", Page 567.. 1st Edition. Addison Wesley. 2006.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-11-24CWE Content TeamMITRE
updated Observed_Examples, Relationships, Taxonomy_Mappings
2009-07-27CWE Content TeamMITRE
updated Other_Notes, Relationship_Notes
2009-10-29CWE Content TeamMITRE
updated Observed_Examples
2010-02-16CWE Content TeamMITRE
updated Potential_Mitigations, Relationships, Taxonomy_Mappings
2010-04-05CWE Content TeamMITRE
updated Related_Attack_Patterns
2010-06-21CWE Content TeamMITRE
updated Observed_Examples, Relationships
2010-09-27CWE Content TeamMITRE
updated Relationships
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, Demonstrative_Examples, Observed_Examples, References, Related_Attack_Patterns, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-06-23CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2015-12-07CWE Content TeamMITRE
updated Demonstrative_Examples, Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Causal_Nature, Modes_of_Introduction, Relationships, Taxonomy_Mappings

CWE-587: Assignment of a Fixed Address to a Pointer

Weakness ID: 587
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The software sets a pointer to a specific address other than NULL or 0.
+ Extended Description
Using a fixed address is not portable because that address will probably not be valid in all environments or platforms.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory465Pointer Issues
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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: (Undetermined Prevalence)

C++: (Undetermined Prevalence)

C#: (Undetermined Prevalence)

(Assembly classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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

If one executes code at a known location, an attacker might be able to inject code there beforehand.
Availability

Technical Impact: DoS: Crash, Exit, or Restart

If the code is ported to another platform or environment, the pointer is likely to be invalid and cause a crash.
Confidentiality
Integrity

Technical Impact: Read Memory; Modify Memory

The data at a known pointer location can be easily read or influenced by an attacker.
+ Demonstrative Examples

Example 1

This code assumes a particular function will always be found at a particular address. It assigns a pointer to that address and calls the function.

(bad)
Example Language:
int (*pt2Function) (float, char, char)=0x08040000;
int result2 = (*pt2Function) (12, 'a', 'b');
// Here we can inject code to execute.

The same function may not always be found at the same memory address. This could lead to a crash, or an attacker may alter the memory at the expected address, leading to arbitrary code execution.

+ Potential Mitigations

Phase: Implementation

Never set a pointer to a fixed address.
+ Weakness Ordinalities
OrdinalityDescription
Primary
(where the weakness exists independent of other weaknesses)
+ Memberships
This 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.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CERT C Secure CodingINT36-CImpreciseConverting a pointer to integer or integer to pointer
Software Fault PatternsSFP1Glitch in computation
+ Content History
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-08-01KDM Analytics
added/updated white box definitions
2008-09-08CWE Content TeamMITRE
updated Applicable_Platforms, Description, Relationships, Other_Notes, Weakness_Ordinalities
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-03-10CWE Content TeamMITRE
updated Relationships
2009-07-27CWE Content TeamMITRE
updated Common_Consequences, Description, Other_Notes
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Demonstrative_Examples, Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Taxonomy_Mappings, White_Box_Definitions

CWE-294: Authentication Bypass by Capture-replay

Weakness ID: 294
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
A capture-replay flaw exists when the design of the software makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).
+ Extended Description
Capture-replay attacks are common and can be difficult to defeat without cryptography. They are a subset of network injection attacks that rely on observing previously-sent valid commands, then changing them slightly if necessary and resending the same commands to the server.
+ Relationships

The table(s) below 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
ChildOfClassClass287Improper Authentication
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory1010Authenticate Actors
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
ChildOfClassClass287Improper Authentication
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and DesignCOMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
+ Applicable Platforms
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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: Gain Privileges or Assume Identity

Messages sent with a capture-relay attack allow access to resources which are not otherwise accessible without proper authentication.
+ Likelihood Of Exploit
High
+ Observed Examples
ReferenceDescription
product authentication succeeds if user-provided MD5 hash matches the hash in its database; this can be subjected to replay attacks.
Chain: cleartext transmission of the MD5 hash of password (CWE-319) enables attacks against a server that is susceptible to replay (CWE-294).
+ Potential Mitigations

Phase: Architecture and Design

Utilize some sequence or time stamping functionality along with a checksum which takes this into account in order to ensure that messages can be parsed only once.

Phase: Architecture and Design

Since any attacker who can listen to traffic can see sequence numbers, it is necessary to sign messages with some kind of cryptography to ensure that sequence numbers are not simply doctored along with content.
+ Memberships
This 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
MemberOfViewView884CWE Cross-section
MemberOfCategoryCategory956SFP Secondary Cluster: Channel Attack
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERAuthentication bypass by replay
CLASPCapture-replay
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-09-08CWE Content TeamMITRE
updated Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
2009-05-27CWE Content TeamMITRE
updated Related_Attack_Patterns
2009-07-27CWE Content TeamMITRE
updated Description, Other_Notes, Potential_Mitigations
2009-10-29CWE Content TeamMITRE
updated Observed_Examples
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples
2012-05-11CWE Content TeamMITRE
updated Observed_Examples, Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-05-03CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Modes_of_Introduction, Relationships

CWE-305: Authentication Bypass by Primary Weakness

Weakness ID: 305
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error.
+ Relationships

The table(s) below 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
ChildOfClassClass287Improper Authentication
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory1010Authenticate Actors
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
ChildOfClassClass287Improper Authentication
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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

+ Observed Examples
ReferenceDescription
The provided password is only compared against the first character of the real password.
The password is not properly checked, which allows remote attackers to bypass access controls by sending a 1-byte password that matches the first character of the real password.
Chain: Forum software does not properly initialize an array, which inadvertently sets the password to a single character, allowing remote attackers to easily guess the password and gain administrative privileges.
+ Memberships
This 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
MemberOfCategoryCategory947SFP Secondary Cluster: Authentication Bypass
+ Notes

Relationship

Most "authentication bypass" errors are resultant, not primary.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERAuthentication Bypass by Primary Weakness
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Relationship_Notes, Taxonomy_Mappings
2008-11-24CWE Content TeamMITRE
updated Observed_Examples
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Observed_Examples, Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-05-03CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Modes_of_Introduction, Relationships

CWE-290: Authentication Bypass by Spoofing

Weakness ID: 290
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
This attack-focused weakness is caused by improperly implemented authentication schemes that are subject to spoofing attacks.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory1010Authenticate Actors
+ Relevant to the view "Development Concepts" (CWE-699)
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and DesignCOMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
Implementation
+ Common Consequences

The table below 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; Gain Privileges or Assume Identity

This weakness can allow an attacker to access resources which are not otherwise accessible without proper authentication.
+ Demonstrative Examples

Example 1

The following code authenticates users.

(bad)
Example Language: Java 
String sourceIP = request.getRemoteAddr();
if (sourceIP != null && sourceIP.equals(APPROVED_IP)) {
authenticated = true;

}

The authentication mechanism implemented relies on an IP address for source validation. If an attacker is able to spoof the IP, they may be able to bypass the authentication mechanism.

Example 2

Both of these examples check if a request is from a trusted address before responding to the request.

(bad)
Example Language:
sd = socket(AF_INET, SOCK_DGRAM, 0);
serv.sin_family = AF_INET;
serv.sin_addr.s_addr = htonl(INADDR_ANY);
servr.sin_port = htons(1008);
bind(sd, (struct sockaddr *) & serv, sizeof(serv));

while (1) {
memset(msg, 0x0, MAX_MSG);
clilen = sizeof(cli);
if (inet_ntoa(cli.sin_addr)==getTrustedAddress()) {
n = recvfrom(sd, msg, MAX_MSG, 0, (struct sockaddr *) & cli, &clilen);

}

}
(bad)
Example Language: Java 
while(true) {
DatagramPacket rp=new DatagramPacket(rData,rData.length);
outSock.receive(rp);
String in = new String(p.getData(),0, rp.getLength());
InetAddress clientIPAddress = rp.getAddress();
int port = rp.getPort();

if (isTrustedAddress(clientIPAddress) & secretKey.equals(in)) {
out = secret.getBytes();
DatagramPacket sp =new DatagramPacket(out,out.length, IPAddress, port); outSock.send(sp);

}

}

The code only verifies the address as stored in the request packet. An attacker can spoof this address, thus impersonating a trusted client

Example 3

The following code samples use a DNS lookup in order to decide whether or not an inbound request is from a trusted host. If an attacker can poison the DNS cache, they can gain trusted status.

(bad)
Example Language:
struct hostent *hp;struct in_addr myaddr;
char* tHost = "trustme.example.com";
myaddr.s_addr=inet_addr(ip_addr_string);

hp = gethostbyaddr((char *) &myaddr, sizeof(struct in_addr), AF_INET);
if (hp && !strncmp(hp->h_name, tHost, sizeof(tHost))) {
trusted = true;

} else {
trusted = false;

}
(bad)
Example Language: Java 
String ip = request.getRemoteAddr();
InetAddress addr = InetAddress.getByName(ip);
if (addr.getCanonicalHostName().endsWith("trustme.com")) {
trusted = true;

}
(bad)
Example Language: C# 
IPAddress hostIPAddress = IPAddress.Parse(RemoteIpAddress);
IPHostEntry hostInfo = Dns.GetHostByAddress(hostIPAddress);
if (hostInfo.HostName.EndsWith("trustme.com")) {
trusted = true;

}

IP addresses are more reliable than DNS names, but they can also be spoofed. Attackers can easily forge the source IP address of the packets they send, but response packets will return to the forged IP address. To see the response packets, the attacker has to sniff the traffic between the victim machine and the forged IP address. In order to accomplish the required sniffing, attackers typically attempt to locate themselves on the same subnet as the victim machine. Attackers may be able to circumvent this requirement by using source routing, but source routing is disabled across much of the Internet today. In summary, IP address verification can be a useful part of an authentication scheme, but it should not be the single factor required for authentication.

+ Observed Examples
ReferenceDescription
VOIP product allows authentication bypass using 127.0.0.1 in the Host header.
+ Memberships
This 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
MemberOfViewView884CWE Cross-section
MemberOfCategoryCategory956SFP Secondary Cluster: Channel Attack
+ Notes

Relationship

This can be resultant from insufficient verification.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERAuthentication bypass by spoofing
+ References
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 3, "Spoofing and Identification", Page 72.. 1st Edition. Addison Wesley. 2006.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Sean EidemillerCigital
added/updated demonstrative examples
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Description, Relationships, Relationship_Notes, Taxonomy_Mappings
2009-07-27CWE Content TeamMITRE
updated Relationship_Notes
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Observed_Examples, References, Related_Attack_Patterns, Relationships
2013-07-17CWE Content TeamMITRE
updated Relationships
2014-02-18CWE Content TeamMITRE
updated Related_Attack_Patterns
2014-07-30CWE Content TeamMITRE
updated Demonstrative_Examples, Relationships
2017-05-03CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Demonstrative_Examples, Modes_of_Introduction, Relationships

CWE-288: Authentication Bypass Using an Alternate Path or Channel

Weakness ID: 288
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
A product requires authentication, but the product has an alternate path or channel that does not require authentication.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory1010Authenticate Actors
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory840Business Logic Errors
ChildOfClassClass287Improper Authentication
ParentOfBaseBase425Direct Request ('Forced Browsing')
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and DesignCOMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
Architecture and DesignThis is often seen in web applications that assume that access to a particular CGI program can only be obtained through a "front" screen, when the supporting programs are directly accessible. But this problem is not just in web apps.
+ Applicable Platforms
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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

+ Observed Examples
ReferenceDescription
Router allows remote attackers to read system logs without authentication by directly connecting to the login screen and typing certain control characters.
Attackers with physical access to the machine may bypass the password prompt by pressing the ESC (Escape) key.
OS allows local attackers to bypass the password protection of idled sessions via the programmer's switch or CMD-PWR keyboard sequence, which brings up a debugger that the attacker can use to disable the lock.
Direct request of installation file allows attacker to create administrator accounts.
Attackers may gain additional privileges by directly requesting the web management URL.
Bypass authentication via direct request to named pipe.
User can avoid lockouts by using an API instead of the GUI to conduct brute force password guessing.
+ Potential Mitigations

Phase: Architecture and Design

Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.
+ Memberships
This 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.
+ Notes

Relationship

overlaps Unprotected Alternate Channel
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERAuthentication Bypass by Alternate Path/Channel
OWASP Top Ten 2007A10CWE More SpecificFailure to Restrict URL Access
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-09-08CWE Content TeamMITRE
updated Description, Modes_of_Introduction, Name, Relationships, Observed_Example, Relationship_Notes, Taxonomy_Mappings, Type
2008-11-24CWE Content TeamMITRE
updated Observed_Examples
2011-03-29CWE Content TeamMITRE
updated Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Observed_Examples, Related_Attack_Patterns, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-05-03CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Modes_of_Introduction, Relationships
Previous Entry Names
Change DatePrevious Entry Name
2008-09-09Authentication Bypass by Alternate Path/Channel

CWE-639: Authorization Bypass Through User-Controlled Key

Weakness ID: 639
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
+ Extended Description

Retrieval of a user record occurs in the system based on some key value that is under user control. The key would typically identify a user-related record stored in the system and would be used to lookup that record for presentation to the user. It is likely that an attacker would have to be an authenticated user in the system. However, the authorization process would not properly check the data access operation to ensure that the authenticated user performing the operation has sufficient entitlements to perform the requested data access, hence bypassing any other authorization checks present in the system.

For example, attackers can look at places where user specific data is retrieved (e.g. search screens) and determine whether the key for the item being looked up is controllable externally. The key may be a hidden field in the HTML form field, might be passed as a URL parameter or as an unencrypted cookie variable, then in each of these cases it will be possible to tamper with the key value.

One manifestation of this weakness is when a system uses sequential or otherwise easily-guessable session IDs that would allow one user to easily switch to another user's session and read/modify their data.

+ Relationships

The table(s) below 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)
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory1011Authorize Actors
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory840Business Logic Errors
ChildOfClassClass862Missing Authorization
ParentOfVariantVariant566Authorization Bypass Through User-Controlled SQL Primary Key
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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

Access control checks for specific user data or functionality can be bypassed.
Access Control

Technical Impact: Gain Privileges or Assume Identity

Horizontal escalation of privilege is possible (one user can view/modify information of another user).
Access Control

Technical Impact: Gain Privileges or Assume Identity

Vertical escalation of privilege is possible if the user-controlled key is actually a flag that indicates administrator status, allowing the attacker to gain administrative access.
+ Alternate Terms
Insecure Direct Object Reference:The "Insecure Direct Object Reference" term, as described in the OWASP Top Ten, is broader than this CWE because it also covers path traversal (CWE-22). Within the context of vulnerability theory, there is a similarity between the OWASP concept and CWE-706: Use of Incorrectly-Resolved Name or Reference.
Horizontal Authorization:"Horizontal Authorization" is used to describe situations in which two users have the same privilege level, but must be prevented from accessing each other's resources. This is fairly common when using key-based access to resources in a multi-user context.
+ Likelihood Of Exploit
High
+ Potential Mitigations

Phase: Architecture and Design

For each and every data access, ensure that the user has sufficient privilege to access the record that is being requested.

Phases: Architecture and Design; Implementation

Make sure that the key that is used in the lookup of a specific user's record is not controllable externally by the user or that any tampering can be detected.

Phase: Architecture and Design

Use encryption in order to make it more difficult to guess other legitimate values of the key or associate a digital signature with the key so that the server can verify that there has been no tampering.
+ Memberships
This 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.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
2008-01-30Evgeny LebanidzeCigital
Modifications
Modification DateModifierOrganizationSource
2008-09-08CWE Content TeamMITRE
updated Common_Consequences, Relationships, Type
2008-10-14CWE Content TeamMITRE
updated Description
2009-03-10CWE Content TeamMITRE
updated Relationships
2009-05-27CWE Content TeamMITRE
updated Relationships
2009-10-29CWE Content TeamMITRE
updated Common_Consequences
2010-06-21CWE Content TeamMITRE
updated Relationships
2011-03-29CWE Content TeamMITRE
updated Alternate_Terms, Applicable_Platforms, Description, Name, Potential_Mitigations, Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships
2012-05-11CWE Content TeamMITRE
updated Relationships
2013-02-21CWE Content TeamMITRE
updated Alternate_Terms, Common_Consequences
2013-07-17CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Description, Enabling_Factors_for_Exploitation, Modes_of_Introduction, Relationships
Previous Entry Names
Change DatePrevious Entry Name
2011-03-29Access Control Bypass Through User-Controlled Key

CWE-439: Behavioral Change in New Version or Environment

Weakness ID: 439
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
A's behavior or functionality changes with a new version of A, or a new environment, which is not known (or manageable) by B.
+ Relationships

The table(s) below 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
ChildOfClassClass435Improper Interaction Between Multiple Entities
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory438Behavioral Problems
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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
Other

Technical Impact: Quality Degradation; Varies by Context

+ Alternate Terms
Functional change
+ Observed Examples
ReferenceDescription
Linux kernel 2.2 and above allow promiscuous mode using a different method than previous versions, and ifconfig is not aware of the new method (alternate path property).
Product uses defunct method from another product that does not return an error code and allows detection avoidance.
chain: Code was ported from a case-sensitive Unix platform to a case-insensitive Windows platform where filetype handlers treat .jsp and .JSP as different extensions. JSP source code may be read because .JSP defaults to the filetype "text".
+ Memberships
This 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
MemberOfCategoryCategory1001SFP Secondary Cluster: Use of an Improper API
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERCHANGE Behavioral Change
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Observed_Example, Taxonomy_Mappings
2008-11-24CWE Content TeamMITRE
updated Observed_Examples
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-06-27CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Behavioral Change

CWE-805: Buffer Access with Incorrect Length Value

Weakness ID: 805
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The software uses a sequential operation to read or write a buffer, but it uses an incorrect length value that causes it to access memory that is outside of the bounds of the buffer.
+ Extended Description
When the length value exceeds the size of the destination, a buffer overflow could occur.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Development Concepts" (CWE-699)
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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)

(Assembly classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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

Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. This can often be used to subvert any other security service.
Availability

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

Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
+ 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)
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 under the assumption that the maximum length value of hostname is 64 bytes, 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 we 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

In the following example, it is possible to request that memcpy move a much larger segment of memory than assumed:

(bad)
Example Language:
int returnChunkSize(void *) {
/* if chunk info is valid, return the size of usable memory,
* else, return -1 to indicate an error
*/
...

}
int main() {
...
memcpy(destBuf, srcBuf, (returnChunkSize(destBuf)-1));
...

}

If returnChunkSize() happens to encounter an error it will return -1. Notice that the return value is not checked before the memcpy operation (CWE-252), so -1 can be passed as the size argument to memcpy() (CWE-805). Because memcpy() assumes that the value is unsigned, it will be interpreted as MAXINT-1 (CWE-195), and therefore will copy far more memory than is likely available to the destination buffer (CWE-787, CWE-788).

Example 3

In the following example, the source character string is copied to the dest character string using the method strncpy.

(bad)
Example Language:
...
char source[21] = "the character string";
char dest[12];
strncpy(dest, source, sizeof(source)-1);
...

However, in the call to strncpy the source character string is used within the sizeof call to determine the number of characters to copy. This will create a buffer overflow as the size of the source character string is greater than the dest character string. The dest character string should be used within the sizeof call to ensure that the correct number of characters are copied, as shown below.

(good)
Example Language:
...
char source[21] = "the character string";
char dest[12];
strncpy(dest, source, sizeof(dest)-1);
...

Example 4

In this example, the method outputFilenameToLog outputs a filename to a log file. The method arguments include a pointer to a character string containing the file name and an integer for the number of characters in the string. The filename is copied to a buffer where the buffer size is set to a maximum size for inputs to the log file. The method then calls another method to save the contents of the buffer to the log file.

(bad)
Example Language:
#define LOG_INPUT_SIZE 40
// saves the file name to a log file

int outputFilenameToLog(char *filename, int length) {
int success;
// buffer with size set to maximum size for input to log file

char buf[LOG_INPUT_SIZE];
// copy filename to buffer

strncpy(buf, filename, length);
// save to log file

success = saveToLogFile(buf);

return success;

}

However, in this case the string copy method, strncpy, mistakenly uses the length method argument to determine the number of characters to copy rather than using the size of the local character string, buf. This can lead to a buffer overflow if the number of characters contained in character string pointed to by filename is larger then the number of characters allowed for the local character string. The string copy method should use the buf character string within a sizeof call to ensure that only characters up to the size of the buf array are copied to avoid a buffer overflow, as shown below.

(good)
Example Language:
...
// copy filename to buffer

strncpy(buf, filename, sizeof(buf)-1);
...
+ Observed Examples
ReferenceDescription
Chain: large length value causes buffer over-read (CWE-126)
Use of packet length field to make a calculation, then copy into a fixed-size buffer
Chain: retrieval of length value from an uninitialized memory location
Crafted length value in document reader leads to buffer overflow
SSL server overflow when the sum of multiple length fields exceeds a given value
Language interpreter API function doesn't validate length argument, leading to information exposure
+ 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.
This is not a complete solution, since many buffer overflows are not related to strings.

Phase: Build and Compilation

Strategy: Compilation or Build Hardening

Run or compile the software using features or extensions that automatically provide a protection mechanism that mitigates or eliminates buffer overflows. For example, certain compilers and extensions provide automatic buffer overflow detection mechanisms that are built into the compiled code. Examples include the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice.

Effectiveness: Defense in Depth

This is not necessarily a complete solution, since these mechanisms can only detect certain types of overflows. In addition, an attack could still cause 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 your buffer is as large as you specify. 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 you are not in 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.

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: Operation

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].

Effectiveness: Defense in Depth

This is not a complete solution. However, it forces the attacker to guess an unknown value that changes every program execution. In addition, an attack could still cause a denial of service, since the typical response is to exit the application.

Phase: Operation

Strategy: Environment Hardening

Use a CPU and operating system that offers Data Execution Protection (NX) or its equivalent [REF-59] [REF-57].

Effectiveness: Defense in Depth

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.

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: 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

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.
+ Weakness Ordinalities
OrdinalityDescription
Resultant
(where the weakness is typically related to the presence of some other weaknesses)
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.

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

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.

Effectiveness: Moderate

Without visibility into the code, black box methods may not be able to sufficiently distinguish this weakness from others, requiring manual methods to diagnose the underlying problem.

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.
+ Affected Resources
  • Memory
+ Memberships
This 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.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CERT C Secure CodingARR38-CImpreciseGuarantee that library functions do not form invalid pointers
+ References
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 6, "Why ACLs Are Important" Page 171. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoft.com/mspress/books/toc/5957.aspx>.
[REF-58] Michael Howard. "Address Space Layout Randomization in Windows Vista". <http://blogs.msdn.com/michael_howard/archive/2006/05/26/address-space-layout-randomization-in-windows-vista.aspx>.
[REF-59] Arjan van de Ven. "Limiting buffer overflows with ExecShield". <http://www.redhat.com/magazine/009jul05/features/execshield/>.
[REF-741] Jason Lam. "Top 25 Series - Rank 12 - Buffer Access with Incorrect Length Value". SANS Software Security Institute. 2010-03-11. <http://blogs.sans.org/appsecstreetfighter/2010/03/11/top-25-series-rank-12-buffer-access-with-incorrect-length-value/>.
[REF-57] Matt Messier and John Viega. "Safe C String Library v1.0.3". <http://www.zork.org/safestr/>.
[REF-56] Microsoft. "Using the Strsafe.h Functions". <http://msdn.microsoft.com/en-us/library/ms647466.aspx>.
[REF-61] Microsoft. "Understanding DEP as a mitigation technology part 1". <http://blogs.technet.com/b/srd/archive/2009/06/12/understanding-dep-as-a-mitigation-technology-part-1.aspx>.
[REF-76] Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://buildsecurityin.us-cert.gov/daisy/bsi/articles/knowledge/principles/351.html>.
[REF-64] Grant Murphy. "Position Independent Executables (PIE)". Red Hat. 2012-11-28. <https://securityblog.redhat.com/2012/11/28/position-independent-executables-pie/>.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
2010-01-15CWE Content TeamMITRE
Modifications
Modification DateModifierOrganizationSource
2010-04-05CWE Content TeamMITRE
updated Related_Attack_Patterns
2010-06-21CWE Content TeamMITRE
updated Common_Consequences, Potential_Mitigations, References
2010-09-27CWE Content TeamMITRE
updated Potential_Mitigations
2010-12-13CWE Content TeamMITRE
updated Potential_Mitigations
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-06-27CWE Content TeamMITRE
updated Demonstrative_Examples, Observed_Examples, Relationships
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Potential_Mitigations, References, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-02-18CWE Content TeamMITRE
updated Potential_Mitigations, References
2014-06-23CWE Content TeamMITRE
updated Demonstrative_Examples
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Causal_Nature, Demonstrative_Examples, Likelihood_of_Exploit, References, Taxonomy_Mappings

CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Weakness ID: 120
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The program copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow.
+ Extended Description
A buffer overflow condition exists when a program attempts to put more data in a buffer than it can hold, or when a program attempts to put data in a memory area outside of the boundaries of a buffer. The simplest type of error, and the most common cause of buffer overflows, is the "classic" case in which the program copies the buffer without restricting how much is copied. Other variants exist, but the existence of a classic overflow strongly suggests that the programmer is not considering even the most basic of security protections.
+ Relationships

The table(s) below 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 "Development Concepts" (CWE-699)
+ Relevant to the view "Seven Pernicious Kingdoms" (CWE-700)
NatureTypeIDName
ChildOfClassClass20Improper Input Validation
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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: (Undetermined Prevalence)

C++: (Undetermined Prevalence)

(Assembly classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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

Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. This can often be used to subvert any other security service.
Availability

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

Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
+ Alternate Terms
buffer overrun:Some prominent vendors and researchers use the term "buffer overrun," but most people use "buffer overflow."
Unbounded Transfer
+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

The following code asks the user to enter their last name and then attempts to store the value entered in the last_name array.

(bad)
Example Language:
char last_name[20];
printf ("Enter your last name: ");
scanf ("%s", last_name);

The problem with the code above is that it does not restrict or limit the size of the name entered by the user. If the user enters "Very_very_long_last_name" which is 24 characters long, then a buffer overflow will occur since the array can only hold 20 characters total.

Example 2

The following code attempts to create a local copy of a buffer to perform some manipulations to the data.

(bad)
Example Language:
void manipulate_string(char* string){
char buf[24];
strcpy(buf, string);
...

}

However, the programmer does not ensure that the size of the data pointed to by string will fit in the local buffer and blindly copies the data with the potentially dangerous strcpy() function. This may result in a buffer overflow condition if an attacker can influence the contents of the string parameter.

Example 3

The excerpt below calls the gets() function in C, which is inherently unsafe.

(bad)
Example Language:
char buf[24];
printf("Please enter your name and press <Enter>\n");
gets(buf);
...
}

However, the programmer uses the function gets() which is inherently unsafe because it blindly copies all input from STDIN to the buffer without restricting how much is copied. This allows the user to provide a string that is larger than the buffer size, resulting in an overflow condition.

Example 4

In the following example, a server accepts connections from a client and processes the client request. After accepting a client connection, the program will obtain client information using the gethostbyaddr method, copy the hostname of the client that connected to a local variable and output the hostname of the client to a log file.

(bad)
Example Language:
...
struct hostent *clienthp;
char hostname[MAX_LEN];

// create server socket, bind to server address and listen on socket
...

// accept client connections and process requests
int count = 0;
for (count = 0; count < MAX_CONNECTIONS; count++) {

int clientlen = sizeof(struct sockaddr_in);
int clientsocket = accept(serversocket, (struct sockaddr *)&clientaddr, &clientlen);

if (clientsocket >= 0) {
clienthp = gethostbyaddr((char*) &clientaddr.sin_addr.s_addr, sizeof(clientaddr.sin_addr.s_addr), AF_INET);
strcpy(hostname, clienthp->h_name);
logOutput("Accepted client connection from host ", hostname);

// process client request
...
close(clientsocket);

}

}
close(serversocket);

...

However, the hostname of the client that connected may be longer than the allocated size for the local hostname variable. This will result in a buffer overflow when copying the client hostname to the local variable using the strcpy method.

+ Observed Examples
ReferenceDescription
buffer overflow using command with long argument
buffer overflow in local program using long environment variable
buffer overflow in comment characters, when product increments a counter for a ">" but does not decrement for "<"
By replacing a valid cookie value with an extremely long string of characters, an attacker may overflow the application's buffers.
By replacing a valid cookie value with an extremely long string of characters, an attacker may overflow the application's buffers.
+ 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.
This is not a complete solution, since many buffer overflows are not related to strings.

Phase: Build and Compilation

Strategy: Compilation or Build Hardening

Run or compile the software using features or extensions that automatically provide a protection mechanism that mitigates or eliminates buffer overflows. For example, certain compilers and extensions provide automatic buffer overflow detection mechanisms that are built into the compiled code. Examples include the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice.

Effectiveness: Defense in Depth

This is not necessarily a complete solution, since these mechanisms can only detect certain types of overflows. In addition, an attack could still cause 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 your buffer is as large as you specify. 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 you are not in 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.

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a whitelist 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 (i.e., do not rely on a blacklist). A blacklist 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, blacklists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

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: Operation

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].

Effectiveness: Defense in Depth

This is not a complete solution. However, it forces the attacker to guess an unknown value that changes every program execution. In addition, an attack could still cause a denial of service, since the typical response is to exit the application.

Phase: Operation

Strategy: Environment Hardening

Use a CPU and operating system that offers Data Execution Protection (NX) or its equivalent [REF-60] [REF-61].

Effectiveness: Defense in Depth

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.

Phases: Build and Compilation; Operation

Most mitigating technologies at the compiler or OS level to date address only a subset of buffer overflow problems and rarely provide complete protection against even that subset. It is good practice to implement strategies to increase the workload of an attacker, such as leaving the attacker to guess an unknown value that changes every program execution.

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

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).

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.

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: 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

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.
+ Weakness Ordinalities
OrdinalityDescription
Resultant
(where the weakness is typically related to the presence of some other weaknesses)
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.

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

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.

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

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

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
  • Memory Management
+ Affected Resources
  • Memory
+ Memberships
This 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.
+ Notes

Relationship

At the code level, stack-based and heap-based overflows do not differ significantly, so there usually is not a need to distinguish them. From the attacker perspective, they can be quite different, since different techniques are required to exploit them.

Terminology

Many issues that are now called "buffer overflows" are substantively different than the "classic" overflow, including entirely different bug types that rely on overflow exploit techniques, such as integer signedness errors, integer overflows, and format string bugs. This imprecise terminology can make it difficult to determine which variant is being reported.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERUnbounded Transfer ('classic overflow')
7 Pernicious KingdomsBuffer Overflow
CLASPBuffer overflow
OWASP Top Ten 2004A1CWE More SpecificUnvalidated Input
OWASP Top Ten 2004A5CWE More SpecificBuffer Overflows
CERT C Secure CodingSTR31-CExactGuarantee that storage for strings has sufficient space for character data and the null terminator
WASC7Buffer Overflow
Software Fault PatternsSFP8Faulty Buffer Access
+ References
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 5, "Public Enemy #1: The Buffer Overrun" Page 127. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoft.com/mspress/books/toc/5957.aspx>.
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 5: Buffer Overruns." Page 89. McGraw-Hill. 2010.
[REF-56] Microsoft. "Using the Strsafe.h Functions". <http://msdn.microsoft.com/en-us/library/ms647466.aspx>.
[REF-57] Matt Messier and John Viega. "Safe C String Library v1.0.3". <http://www.zork.org/safestr/>.
[REF-58] Michael Howard. "Address Space Layout Randomization in Windows Vista". <http://blogs.msdn.com/michael_howard/archive/2006/05/26/address-space-layout-randomization-in-windows-vista.aspx>.
[REF-59] Arjan van de Ven. "Limiting buffer overflows with ExecShield". <http://www.redhat.com/magazine/009jul05/features/execshield/>.
[REF-74] Jason Lam. "Top 25 Series - Rank 3 - Classic Buffer Overflow". SANS Software Security Institute. 2010-03-02. <http://software-security.sans.org/blog/2010/03/02/top-25-series-rank-3-classic-buffer-overflow/>.
[REF-61] Microsoft. "Understanding DEP as a mitigation technology part 1". <http://blogs.technet.com/b/srd/archive/2009/06/12/understanding-dep-as-a-mitigation-technology-part-1.aspx>.
[REF-76] Sean Barnum and Michael Gegick. "Least Privilege". 2005-09-14. <https://buildsecurityin.us-cert.gov/daisy/bsi/articles/knowledge/principles/351.html>.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 3, "Nonexecutable Stack", Page 76.. 1st Edition. Addison Wesley. 2006.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 5, "Protection Mechanisms", Page 189.. 1st Edition. Addison Wesley. 2006.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 8, "C String Handling", Page 388.. 1st Edition. Addison Wesley. 2006.
[REF-64] Grant Murphy. "Position Independent Executables (PIE)". Red Hat. 2012-11-28. <https://securityblog.redhat.com/2012/11/28/position-independent-executables-pie/>.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
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 Alternate_Terms, Applicable_Platforms, Common_Consequences, Relationships, Observed_Example, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2008-10-10CWE Content TeamMITRE
Changed name and description to more clearly emphasize the "classic" nature of the overflow.
2008-10-14CWE Content TeamMITRE
updated Alternate_Terms, Description, Name, Other_Notes, Terminology_Notes
2008-11-24CWE Content TeamMITRE
updated Other_Notes, Relationships, Taxonomy_Mappings
2009-01-12CWE Content TeamMITRE
updated Common_Consequences, Other_Notes, Potential_Mitigations, References, Relationship_Notes, Relationships
2009-07-27CWE Content TeamMITRE
updated Other_Notes, Potential_Mitigations, Relationships
2009-10-29CWE Content TeamMITRE
updated Common_Consequences, Relationships
2010-02-16CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Demonstrative_Examples, Detection_Factors, Potential_Mitigations, References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings, Time_of_Introduction, Type
2010-04-05CWE Content TeamMITRE
updated Demonstrative_Examples, Related_Attack_Patterns
2010-06-21CWE Content TeamMITRE
updated Common_Consequences, Potential_Mitigations, References
2010-09-27CWE Content TeamMITRE
updated Potential_Mitigations
2010-12-13CWE Content TeamMITRE
updated Potential_Mitigations
2011-03-29CWE Content TeamMITRE
updated Demonstrative_Examples, 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, Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated References, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-02-18CWE Content TeamMITRE
updated Potential_Mitigations, References
2014-07-30CWE Content TeamMITRE
updated Detection_Factors, Relationships, Taxonomy_Mappings
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Causal_Nature, Demonstrative_Examples, Likelihood_of_Exploit, References, Relationships, Taxonomy_Mappings, White_Box_Definitions
Previous Entry Names
Change DatePrevious Entry Name
2008-10-14Unbounded Transfer ('Classic Buffer Overflow')

CWE-124: Buffer Underwrite ('Buffer Underflow')

Weakness ID: 124
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The software writes to a buffer using an index or pointer that references a memory location prior to the beginning of the buffer.
+ Extended Description
This typically occurs when a pointer or its index is decremented to a position before the buffer, when pointer arithmetic results in a position before the beginning of the valid memory location, or when a negative index is used.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Development Concepts" (CWE-699)
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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: (Undetermined Prevalence)

C++: (Undetermined Prevalence)

+ Common Consequences

The table below 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
Availability

Technical Impact: Modify Memory; DoS: Crash, Exit, or Restart

Out of bounds memory access will very likely result in the corruption of relevant memory, and perhaps instructions, possibly leading to a crash.
Integrity
Confidentiality
Availability
Access Control
Other

Technical Impact: Execute Unauthorized Code or Commands; Modify Memory; Bypass Protection Mechanism; Other

If the corrupted memory can be effectively controlled, it may be possible to execute arbitrary code. If the corrupted memory is data rather than instructions, the system will continue to function with improper changes, possibly in violation of an implicit or explicit policy. The consequences would only be limited by how the affected data is used, such as an adjacent memory location that is used to specify whether the user has special privileges.
Access Control
Other

Technical Impact: Bypass Protection Mechanism; Other

When the consequence is arbitrary code execution, this can often be used to subvert any other security service.
+ Alternate Terms
buffer underrun:Some prominent vendors and researchers use the term "buffer underrun". "Buffer underflow" is more commonly used, although both terms are also sometimes used to describe a buffer under-read (CWE-127).
+ Likelihood Of Exploit
Medium
+ Demonstrative Examples

Example 1

In the following C/C++ example, a utility function is used to trim trailing whitespace from a character string. The function copies the input string to a local character string and uses a while statement to remove the trailing whitespace by moving backward through the string and overwriting whitespace with a NUL character.

(bad)
Example Language:
char* trimTrailingWhitespace(char *strMessage, int length) {
char *retMessage;
char *message = malloc(sizeof(char)*(length+1));
// copy input string to a temporary string

char message[length+1];
int index;
for (index = 0; index < length; index++) {
message[index] = strMessage[index];

}
message[index] = '\0';
// trim trailing whitespace

int len = index-1;
while (isspace(message[len])) {
message[len] = '\0';
len--;

}
// return string without trailing whitespace

retMessage = message;
return retMessage;

}

However, this function can cause a buffer underwrite if the input character string contains all whitespace. On some systems the while statement will move backwards past the beginning of a character string and will call the isspace() function on an address outside of the bounds of the local buffer.

Example 2

The following is an example of code that may result in a buffer underwrite, if find() returns a negative value to indicate that ch is not found in srcBuf:

(bad)
Example Language:
int main() {
...
strncpy(destBuf, &srcBuf[find(srcBuf, ch)], 1024);
...

}

If the index to srcBuf is somehow under user control, this is an arbitrary write-what-where condition.

+ Observed Examples
ReferenceDescription
Unchecked length of SSLv2 challenge value leads to buffer underflow.
Buffer underflow from a small size value with a large buffer (length parameter inconsistency, CWE-130)
Buffer underflow from an all-whitespace string, which causes a counter to be decremented before the buffer while looking for a non-whitespace character.
Buffer underflow resultant from encoded data that triggers an integer overflow.
Product sets an incorrect buffer size limit, leading to "off-by-two" buffer underflow.
Negative value is used in a memcpy() operation, leading to buffer underflow.
Buffer underflow due to mishandled special characters
+ Potential Mitigations
Requirements specification: The choice could be made to use a language that is not susceptible to these issues.

Phase: Implementation

Sanity checks should be performed on all calculated values used as index or for pointer arithmetic.
+ Weakness Ordinalities
OrdinalityDescription
Primary
(where the weakness exists independent of other weaknesses)
+ Memberships
This 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
MemberOfCategoryCategory970SFP Secondary Cluster: Faulty Buffer Access
+ Notes

Relationship

This could be resultant from several errors, including a bad offset or an array index that decrements before the beginning of the buffer (see CWE-129).

Research Gap

Much attention has been paid to buffer overflows, but "underflows" sometimes exist in products that are relatively free of overflows, so it is likely that this variant has been under-studied.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERUNDER - Boundary beginning violation ('buffer underflow'?)
CLASPBuffer underwrite
Software Fault PatternsSFP8Faulty Buffer Access
+ References
[REF-90] "Buffer UNDERFLOWS: What do you know about it?". Vuln-Dev Mailing List. 2004-01-10. <http://seclists.org/vuln-dev/2004/Jan/0022.html>.
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 5: Buffer Overruns." Page 89. McGraw-Hill. 2010.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Alternate_Terms, Applicable_Platforms, Common_Consequences, Description, Relationships, Relationship_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2009-01-12CWE Content TeamMITRE
updated Common_Consequences
2009-10-29CWE Content TeamMITRE
updated Description, Name, Relationships
2011-03-29CWE Content TeamMITRE
updated Demonstrative_Examples, Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Demonstrative_Examples, References, Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2017-11-08CWE Content TeamMITRE
updated Causal_Nature, Demonstrative_Examples, References
Previous Entry Names
Change DatePrevious Entry Name
2009-10-29Boundary Beginning Violation ('Buffer Underwrite')

CWE-312: Cleartext Storage of Sensitive Information

Weakness ID: 312
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The application stores sensitive information in cleartext within a resource that might be accessible to another control sphere.
+ Extended Description
Because the information is stored in cleartext, attackers could potentially read it. Even if the information is encoded in a way that is not human-readable, certain techniques could determine which encoding is being used, then decode the information.
+ Relationships

The table(s) below 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
MemberOfCategoryCategory1013Encrypt Data
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and DesignOMISSION: This weakness is caused by missing a security tactic during the architecture and design phase.
+ Applicable Platforms
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

Paradigms

Mobile: (Undetermined Prevalence)

+ Common Consequences

The table below 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

An attacker with access to the system could read sensitive information stored in cleartext.
+ Demonstrative Examples

Example 1

The following code excerpt stores a plaintext user account ID in a browser cookie.

(bad)
Example Language: Java 
response.addCookie( new Cookie("userAccountID", acctID);

Because the account ID is in plaintext, the user's account information is exposed if their computer is compromised by an attacker.

Example 2

This code writes a user's login information to a cookie so the user does not have to login again later.

(bad)
Example Language: PHP 
function persistLogin($username, $password){
$data = array("username" => $username, "password"=> $password);
setcookie ("userdata", $data);

}

The code stores the user's username and password in plaintext in a cookie on the user's machine. This exposes the user's login information if their computer is compromised by an attacker. Even if the user's machine is not compromised, this weakness combined with cross-site scripting (CWE-79) could allow an attacker to remotely copy the cookie.

Also note this example code also exhibits Plaintext Storage in a Cookie (CWE-315).

Example 3

The following code attempts to establish a connection, read in a password, then store it to a buffer.

(bad)
Example Language:
server.sin_family = AF_INET; hp = gethostbyname(argv[1]);
if (hp==NULL) error("Unknown host");
memcpy( (char *)&server.sin_addr,(char *)hp->h_addr,hp->h_length);
if (argc < 3) port = 80;
else port = (unsigned short)atoi(argv[3]);
server.sin_port = htons(port);
if (connect(sock, (struct sockaddr *)&server, sizeof server) < 0) error("Connecting");
...
while ((n=read(sock,buffer,BUFSIZE-1))!=-1) {

write(dfd,password_buffer,n);
...

While successful, the program does not encrypt the data before writing it to a buffer, possibly exposing it to unauthorized actors.

Example 4

The following examples show a portion of properties and configuration files for Java and ASP.NET applications. The files include username and password information but they are stored in plaintext.

This Java example shows a properties file with a plaintext username / password pair.

(bad)
Example Language: Java 
# Java Web App ResourceBundle properties file
...
webapp.ldap.username=secretUsername
webapp.ldap.password=secretPassword
...

The following example shows a portion of a configuration file for an ASP.Net application. This configuration file includes username and password information for a connection to a database but the pair is stored in plaintext.

(bad)
Example Language: ASP.NET 
...
<connectionStrings>
<add name="ud_DEV" connectionString="connectDB=uDB; uid=db2admin; pwd=password; dbalias=uDB;" providerName="System.Data.Odbc" />
</connectionStrings>
...

Username and password information should not be included in a configuration file or a properties file in plaintext as this will allow anyone who can read the file access to the resource. If possible, encrypt this information and avoid CWE-260 and CWE-13.

+ Observed Examples
ReferenceDescription
password and username stored in cleartext in a cookie
password stored in cleartext in a file with insecure permissions
chat program disables SSL in some circumstances even when the user says to use SSL.
Chain: product uses an incorrect public exponent when generating an RSA key, which effectively disables the encryption
storage of unencrypted passwords in a database
storage of unencrypted passwords in a database
product stores a password in cleartext in memory
storage of a secret key in cleartext in a temporary file
SCADA product uses HTTP Basic Authentication, which is not encrypted
login credentials stored unencrypted in a registry key
Plaintext credentials in world-readable file.
Password in cleartext in config file.
Password in cleartext in config file.
Decrypted copy of a message written to disk given a combination of options and when user replies to an encrypted message.
Plaintext storage of private key and passphrase in log file when user imports the key.
Admin password in plaintext in a cookie.
Default configuration has cleartext usernames/passwords in cookie.
Usernames/passwords in cleartext in cookies.
Authentication information stored in cleartext in a cookie.
+ Memberships
This 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.
+ Notes

Terminology

Different people use "cleartext" and "plaintext" to mean the same thing: the lack of encryption. However, within cryptography, these have more precise meanings. Plaintext is the information just before it is fed into a cryptographic algorithm, including already-encrypted text. Cleartext is any information that is unencrypted, although it might be in an encoded form that is not easily human-readable (such as base64 encoding).
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERPlaintext Storage of Sensitive Information
Software Fault PatternsSFP23Exposed Data
+ References
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 9, "Protecting Secret Data" Page 299. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoft.com/mspress/books/toc/5957.aspx>.
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 2, "Common Vulnerabilities of Encryption", Page 43.. 1st Edition. Addison Wesley. 2006.
[REF-172] Chris Wysopal. "Mobile App Top 10 List". 2010-12-13. <http://www.veracode.com/blog/2010/12/mobile-app-top-10-list/>.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-01-12CWE Content TeamMITRE
updated Description, Name
2010-02-16CWE Content TeamMITRE
updated References
2010-06-21CWE Content TeamMITRE
updated Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Observed_Examples, References, Related_Attack_Patterns, Relationships
2013-02-21CWE Content TeamMITRE
updated Applicable_Platforms, References
2013-07-17CWE Content TeamMITRE
updated Description, Relationships, Terminology_Notes
2014-07-30CWE Content TeamMITRE
updated Demonstrative_Examples, Relationships, Taxonomy_Mappings
2017-05-03CWE Content TeamMITRE
updated Related_Attack_Patterns
2017-11-08CWE Content TeamMITRE
updated Modes_of_Introduction, References, Relationships
Previous Entry Names
Change DatePrevious Entry Name
2009-01-12Plaintext Storage of Sensitive Information

CWE-319: Cleartext Transmission of Sensitive Information

Weakness ID: 319
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The software transmits sensitive or security-critical data in cleartext in a communication channel that can be sniffed by unauthorized actors.
+ Extended Description
Many communication channels can be "sniffed" by attackers during data transmission. For example, network traffic can often be sniffed by any attacker who has access to a network interface. This significantly lowers the difficulty of exploitation by attackers.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory1013Encrypt Data
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
ChildOfBaseBase311Missing Encryption of Sensitive Data
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and DesignOMISSION: This weakness is caused by missing a security tactic during the architecture and design phase.
Operation
System Configuration
+ Applicable Platforms
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

Paradigms

Mobile: (Undetermined Prevalence)

+ Common Consequences

The table below 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

Technical Impact: Read Application Data; Modify Files or Directories

Anyone can read the information by gaining access to the channel being used for communication.
+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

The following code attempts to establish a connection to a site to communicate sensitive information.

(bad)
Example Language: Java 
try {
URL u = new URL("http://www.secret.example.org/");
HttpURLConnection hu = (HttpURLConnection) u.openConnection();
hu.setRequestMethod("PUT");
hu.connect();
OutputStream os = hu.getOutputStream();
hu.disconnect();

}
catch (IOException e) {
//...

}

Though a connection is successfully made, the connection is unencrypted and it is possible that all sensitive data sent to or received from the server will be read by unintended actors.

+ Observed Examples
ReferenceDescription
Passwords transmitted in cleartext.
Chain: Use of HTTPS cookie without "secure" flag causes it to be transmitted across unencrypted HTTP.
Product sends password hash in cleartext in violation of intended policy.
Remote management feature sends sensitive information including passwords in cleartext.
Backup routine sends password in cleartext in email.
Product transmits Blowfish encryption key in cleartext.
Printer sends configuration information, including administrative password, in cleartext.
Chain: cleartext transmission of the MD5 hash of password enables attacks against a server that is susceptible to replay (CWE-294).
Product sends passwords in cleartext to a log server.
Product sends file with cleartext passwords in e-mail message intended for diagnostic purposes.
+ Potential Mitigations

Phase: Architecture and Design

Encrypt the data with a reliable encryption scheme before transmitting.

Phase: Implementation

When using web applications with SSL, use SSL for the entire session from login to logout, not just for the initial login page.

Phase: Testing

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

Phase: Operation

Configure servers to use encrypted channels for communication, which may include SSL or other secure protocols.
+ Detection Methods

Black Box

Use monitoring tools that examine the software's process as it interacts with the operating system and the network. This technique is useful in cases when source code is unavailable, if the software was not developed by you, or if you want to verify that the build phase did not introduce any new weaknesses. Examples include debuggers that directly attach to the running process; system-call tracing utilities such as truss (Solaris) and strace (Linux); system activity monitors such as FileMon, RegMon, Process Monitor, and other Sysinternals utilities (Windows); and sniffers and protocol analyzers that monitor network traffic.

Attach the monitor to the process, trigger the feature that sends the data, and look for the presence or absence of common cryptographic functions in the call tree. Monitor the network and determine if the data packets contain readable commands. Tools exist for detecting if certain encodings are in use. If the traffic contains high entropy, this might indicate the usage of encryption.

+ Memberships
This 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.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERPlaintext Transmission of Sensitive Information
CERT Java Secure CodingSEC06-JDo not rely on the default automatic signature verification provided by URLClassLoader and java.util.jar
CERT Java Secure CodingSER02-JSign then seal sensitive objects before sending them outside a trust boundary
Software Fault PatternsSFP23Exposed Data
+ References
[REF-271] OWASP. "Top 10 2007-Insecure Communications". 2007. <http://www.owasp.org/index.php/Top_10_2007-A9>.
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 9, "Protecting Secret Data" Page 299. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoft.com/mspress/books/toc/5957.aspx>.
[REF-44] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 22: Failing to Protect Network Traffic." Page 337. McGraw-Hill. 2010.
[REF-172] Chris Wysopal. "Mobile App Top 10 List". 2010-12-13. <http://www.veracode.com/blog/2010/12/mobile-app-top-10-list/>.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-01-12CWE Content TeamMITRE
updated Common_Consequences, Description, Likelihood_of_Exploit, Name, Observed_Examples, Potential_Mitigations, References, Relationships
2009-03-10CWE Content TeamMITRE
updated Potential_Mitigations
2009-05-27CWE Content TeamMITRE
updated Related_Attack_Patterns
2010-02-16CWE Content TeamMITRE
updated References
2010-04-05CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Time_of_Introduction
2010-06-21CWE Content TeamMITRE
updated Detection_Factors, Relationships
2010-12-13CWE Content TeamMITRE
updated Observed_Examples, Related_Attack_Patterns
2011-03-29CWE Content TeamMITRE
updated Potential_Mitigations
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Demonstrative_Examples, References, Related_Attack_Patterns, Relationships, Taxonomy_Mappings
2013-02-21CWE Content TeamMITRE
updated Applicable_Platforms, References
2013-07-17CWE Content TeamMITRE
updated Relationships
2014-02-18CWE Content TeamMITRE
updated Related_Attack_Patterns
2014-06-23CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2017-05-03CWE Content TeamMITRE
updated Related_Attack_Patterns
2017-11-08CWE Content TeamMITRE
updated Likelihood_of_Exploit, Modes_of_Introduction, References, Relationships
Previous Entry Names
Change DatePrevious Entry Name
2009-01-12Plaintext Transmission of Sensitive Information

CWE-602: Client-Side Enforcement of Server-Side Security

Weakness ID: 602
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The software is composed of a server that relies on the client to implement a mechanism that is intended to protect the server.
+ Extended Description
When the server relies on protection mechanisms placed on the client side, an attacker can modify the client-side behavior to bypass the protection mechanisms resulting in potentially unexpected interactions between the client and server. The consequences will vary, depending on what the mechanisms are trying to protect.
+ Relationships

The table(s) below 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
MemberOfCategoryCategory1012Cross Cutting
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory2547PK - Security Features
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and DesignCOMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
Architecture and DesignConsider a product that consists of two or more processes or nodes that must interact closely, such as a client/server model. If the product uses protection schemes in the client in order to defend from attacks against the server, and the server does not use the same schemes, then an attacker could modify the client in a way that bypasses those schemes. This is a fundamental design flaw that is primary to many weaknesses.
+ Applicable Platforms
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

Paradigms

Client Server: (Sometimes Prevalent)

+ Common Consequences

The table below 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
Availability

Technical Impact: Bypass Protection Mechanism; DoS: Crash, Exit, or Restart

Client-side validation checks can be easily bypassed, allowing malformed or unexpected input to pass into the application, potentially as trusted data. This may lead to unexpected states, behaviors and possibly a resulting crash.
Access Control

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

Client-side checks for authentication can be easily bypassed, allowing clients to escalate their access levels and perform unintended actions.
+ Likelihood Of Exploit
Medium
+ Demonstrative Examples

Example 1

This example contains client-side code that checks if the user authenticated successfully before sending a command. The server-side code performs the authentication in one step, and executes the command in a separate step.

CLIENT-SIDE (client.pl)

(good)
Example Language: Perl 
$server = "server.example.com";
$username = AskForUserName();
$password = AskForPassword();
$address = AskForAddress();
$sock = OpenSocket($server, 1234);
writeSocket($sock, "AUTH $username $password\n");
$resp = readSocket($sock);
if ($resp eq "success") {
# username/pass is valid, go ahead and update the info!
writeSocket($sock, "CHANGE-ADDRESS $username $address\n";

}
else {
print "ERROR: Invalid Authentication!\n";

}

SERVER-SIDE (server.pl):

(bad)
 
$sock = acceptSocket(1234);
($cmd, $args) = ParseClientRequest($sock);
if ($cmd eq "AUTH") {
($username, $pass) = split(/\s+/, $args, 2);
$result = AuthenticateUser($username, $pass);
writeSocket($sock, "$result\n");
# does not close the socket on failure; assumes the
# user will try again

}
elsif ($cmd eq "CHANGE-ADDRESS") {
if (validateAddress($args)) {
$res = UpdateDatabaseRecord($username, "address", $args);
writeSocket($sock, "SUCCESS\n");

}
else {
writeSocket($sock, "FAILURE -- address is malformed\n");

}

}

The server accepts 2 commands, "AUTH" which authenticates the user, and "CHANGE-ADDRESS" which updates the address field for the username. The client performs the authentication and only sends a CHANGE-ADDRESS for that user if the authentication succeeds. Because the client has already performed the authentication, the server assumes that the username in the CHANGE-ADDRESS is the same as the authenticated user. An attacker could modify the client by removing the code that sends the "AUTH" command and simply executing the CHANGE-ADDRESS.

+ Observed Examples
ReferenceDescription
ASP program allows upload of .asp files by bypassing client-side checks.
steganography products embed password information in the carrier file, which can be extracted from a modified client.
steganography products embed password information in the carrier file, which can be extracted from a modified client.
client allows server to modify client's configuration and overwrite arbitrary files.
+ Potential Mitigations

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. 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: Architecture and Design

If some degree of trust is required between the two entities, then use integrity checking and strong authentication to ensure that the inputs are coming from a trusted source. Design the product so that this trust is managed in a centralized fashion, especially if there are complex or numerous communication channels, in order to reduce the risks that the implementer will mistakenly omit a check in a single code path.

Phase: Testing

Use 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.

Phase: Testing

Use 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. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.
+ Weakness Ordinalities
OrdinalityDescription
Primary
(where the weakness exists independent of other weaknesses)
+ Memberships
This 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
MemberOfCategoryCategory722OWASP Top Ten 2004 Category A1 - Unvalidated Input
MemberOfCategoryCategory7532009 Top 25 - Porous Defenses
MemberOfViewView884CWE Cross-section
MemberOfCategoryCategory975SFP Secondary Cluster: Architecture
+ Notes

Research Gap

Server-side enforcement of client-side security is conceptually likely to occur, but some architectures might have these strong dependencies as part of legitimate behavior, such as thin clients.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
OWASP Top Ten 2004A1CWE More SpecificUnvalidated Input
+ References
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 23, "Client-Side Security Is an Oxymoron" Page 687. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoft.com/mspress/books/toc/5957.aspx>.
+ Content History
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities
2009-01-12CWE Content TeamMITRE
updated Demonstrative_Examples, Description, Likelihood_of_Exploit, Name, Observed_Examples, Other_Notes, Potential_Mitigations, Relationships, Research_Gaps, Time_of_Introduction
2009-03-10CWE Content TeamMITRE
updated Potential_Mitigations
2009-05-27CWE Content TeamMITRE
updated Demonstrative_Examples
2009-07-27CWE Content TeamMITRE
updated Related_Attack_Patterns, Relationships
2009-10-29CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences, Description
2010-02-16CWE Content TeamMITRE
updated References
2010-04-05CWE Content TeamMITRE
updated Related_Attack_Patterns
2010-12-13CWE Content TeamMITRE
updated Related_Attack_Patterns
2011-03-29CWE Content TeamMITRE
updated Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-05-03CWE Content TeamMITRE
updated Related_Attack_Patterns
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Enabling_Factors_for_Exploitation, Modes_of_Introduction, References, Relationships
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Client-Side Enforcement of Server-Side Security
2009-01-12Design Principle Violation: Client-Side Enforcement of Server-Side Security

CWE-182: Collapse of Data into Unsafe Value

Weakness ID: 182
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The software filters data in a way that causes it to be reduced or "collapsed" into an unsafe value that violates an expected security property.
+ Relationships

The table(s) below 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
ChildOfClassClass693Protection Mechanism Failure
CanFollowClassClass185Incorrect Regular Expression
CanPrecedeVariantVariant33Path Traversal: '....' (Multiple Dot)
CanPrecedeVariantVariant34Path Traversal: '....//'
CanPrecedeVariantVariant35Path Traversal: '.../...//'
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory171Cleansing, Canonicalization, and Comparison Errors
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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

+ Observed Examples
ReferenceDescription
"/.////" in pathname collapses to absolute path.
"/.//..//////././" is collapsed into "/.././" after ".." and "//" sequences are removed.
".../...//" collapsed to "..." due to removal of "./" in web server.
chain: HTTP server protects against ".." but allows "." variants such as "////./../.../". If the server removes "/.." sequences, the result would collapse into an unsafe value "////../" (CWE-182).
MFV. Regular expression intended to protect against directory traversal reduces ".../...//" to "../".
XSS protection mechanism strips a <script> sequence that is nested in another <script> sequence.
+ Potential Mitigations

Phase: Architecture and Design

Strategy: Input Validation

Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a whitelist 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 (i.e., do not rely on a blacklist). A blacklist 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, blacklists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

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 whitelist validation schemes by introducing dangerous inputs after they have been checked.
Canonicalize the name to match that of the file system's representation of the name. This can sometimes be achieved with an available API (e.g. in Win32 the GetFullPathName function).
+ Memberships
This 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.
+ Notes

Relationship

Overlaps regular expressions, although an implementation might not necessarily use regexp's.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERCollapse of Data into Unsafe Value
CERT Java Secure CodingIDS11-JEliminate noncharacter code points before validation
+ References
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 8, "Character Stripping Vulnerabilities", Page 437.. 1st Edition. Addison Wesley. 2006.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVER
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Description, Relationships, Relationship_Notes, Relevant_Properties, Taxonomy_Mappings
2008-11-24CWE Content TeamMITRE
updated Observed_Examples
2009-03-10CWE Content TeamMITRE
updated Relationships
2009-07-27CWE Content TeamMITRE
updated Potential_Mitigations
2010-06-21CWE Content TeamMITRE
updated Description, Observed_Examples
2010-12-13CWE Content TeamMITRE
updated Relationships
2011-03-29CWE Content TeamMITRE
updated Potential_Mitigations
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated References, Relationships, Taxonomy_Mappings
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Relevant_Properties

CWE-595: Comparison of Object References Instead of Object Contents

Weakness ID: 595
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The program compares object references instead of the contents of the objects themselves, preventing it from detecting equivalent objects.
+ Relationships

The table(s) below 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
ChildOfClassClass697Insufficient Comparison
ParentOfVariantVariant597Use of Wrong Operator in String Comparison
+ Relevant to the view "Development Concepts" (CWE-699)
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software 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
The listings below show 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

Java: (Undetermined Prevalence)

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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
Other

Technical Impact: Other; Varies by Context

This weakness can lead to erroneous results that can cause unexpected application behaviors.
+ Demonstrative Examples

Example 1

In the example below, two Java String objects are declared and initialized with the same string values and an if statement is used to determine if the strings are equivalent.

(bad)
Example Language: Java 
String str1 = new String("Hello");
String str2 = new String("Hello");
if (str1 == str2) {
System.out.println("str1 == str2");

}

However, the if statement will not be executed as the strings are compared using the "==" operator. For Java objects, such as String objects, the "==" operator compares object references, not object values. While the two String objects above contain the same string values, they refer to different object references, so the System.out.println statement will not be executed. To compare object values, the previous code could be modified to use the equals method:

(good)
 
if (str1.equals(str2)) {
System.out.println("str1 equals str2");

}

Example 2

In the following Java example, two BankAccount objects are compared in the isSameAccount method using the == operator.

(bad)
Example Language: Java 
public boolean isSameAccount(BankAccount accountA, BankAccount accountB) {
return accountA == accountB;

}

Using the == operator to compare objects may produce incorrect or deceptive results by comparing object references rather than values. The equals() method should be used to ensure correct results or objects should contain a member variable that uniquely identifies the object.

The following example shows the use of the equals() method to compare the BankAccount objects and the next example uses a class get method to retrieve the bank account number that uniquely identifies the BankAccount object to compare the objects.

(good)
Example Language: Java 
public boolean isSameAccount(BankAccount accountA, BankAccount accountB) {
return accountA.equals(accountB);

}
+ Potential Mitigations

Phase: Implementation

Use the equals() method to compare objects instead of the == operator. If using ==, it is important for performance reasons that your objects are created by a static factory, not by a constructor.
+ Memberships
This 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
MemberOfCategoryCategory847CERT Java Secure Coding Section 02 - Expressions (EXP)
MemberOfViewView884CWE Cross-section
MemberOfCategoryCategory977SFP Secondary Cluster: Design
+ Notes

Other

This problem can cause unexpected application behavior. Comparing objects using == usually produces deceptive results, since the == operator compares object references rather than values. To use == on a string, the programmer has to make sure that these objects are unique in the program, that is, that they don't have the equals method defined or have a static factory that produces unique objects.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CERT Java Secure CodingEXP02-JUse the two-argument Arrays.equals() method to compare the contents of arrays
CERT Java Secure CodingEXP02-JUse the two-argument Arrays.equals() method to compare the contents of arrays
CERT Java Secure CodingEXP03-JDo not use the equality operators when comparing values of boxed primitives
+ Content History
Modifications
Modification DateModifierOrganizationSource
2008-07-01Sean EidemillerCigital
added/updated demonstrative examples
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Description, Relationships, Other_Notes
2009-05-27CWE Content TeamMITRE
updated Name
2010-12-13CWE Content TeamMITRE
updated Demonstrative_Examples
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Relationships, Taxonomy_Mappings
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-06-23CWE Content TeamMITRE
updated Applicable_Platforms, Common_Consequences
2014-07-30CWE Content TeamMITRE
updated Relationships
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Incorrect Object Comparison: Syntactic
2009-05-27Incorrect Syntactic Object Comparison

CWE-733: Compiler Optimization Removal or Modification of Security-critical Code

Weakness ID: 733
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The developer builds a security-critical protection mechanism into the software but the compiler optimizes the program such that the mechanism is removed or modified.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory438Behavioral Problems
ParentOfBaseBase14Compiler Removal of Code to Clear Buffers
+ Applicable Platforms
The listings below show 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)

(Compiled classes): (Undetermined Prevalence)

+ Common Consequences

The table below 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
Other

Technical Impact: Bypass Protection Mechanism; Other

+ Observed Examples
ReferenceDescription
C compiler optimization, as allowed by specifications, removes code that is used to perform checks to detect integer overflows.
+ Detection Methods

Black Box

This specific weakness is impossible to detect using black box methods. While an analyst could examine memory to see that it has not been scrubbed, an analysis of the executable would not be successful. This is because the compiler has already removed the relevant code. Only the source code shows whether the programmer intended to clear the memory or not, so this weakness is indistinguishable from others.

White Box

This weakness is only detectable using white box methods (see black box detection factor). Careful analysis is required to determine if the code is likely to be removed by the compiler.
+ Memberships
This 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
MemberOfCategoryCategory976SFP Secondary Cluster: Compiler
+ References
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 9, "A Compiler Optimization Caveat" Page 322. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoft.com/mspress/books/toc/5957.aspx>.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
2008-10-01CWE Content TeamMITRE
new weakness-focused entry for Research view closes the gap between 14 and 435.
Modifications
Modification DateModifierOrganizationSource
2008-11-24CWE Content TeamMITRE
updated Detection_Factors
2009-03-10CWE Content TeamMITRE
updated Applicable_Platforms, Observed_Examples, Related_Attack_Patterns, Relationships
2010-02-16CWE Content TeamMITRE
updated References
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated References, Relationships

CWE-14: Compiler Removal of Code to Clear Buffers

Weakness ID: 14
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
Sensitive memory is cleared according to the source code, but compiler optimizations leave the memory untouched when it is not read from again, aka "dead store removal."
+ Extended Description

This compiler optimization error occurs when:

1. Secret data are stored in memory.
2. The secret data are scrubbed from memory by overwriting its contents.
3. The source code is compiled using an optimizing compiler, which identifies and removes the function that overwrites the contents as a dead store because the memory is not used subsequently.
+ Relationships

The table(s) below 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)
+ Relevant to the view "Development Concepts" (CWE-699)
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Implementation
Build and Compilation
+ Applicable Platforms
The listings below show 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: (Undetermined Prevalence)

C++: (Undetermined Prevalence)

+ Common Consequences

The table below 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
Access Control

Technical Impact: Read Memory; Bypass Protection Mechanism

This weakness will allow data that has not been cleared from memory to be read. If this data contains sensitive password information, then an attacker can read the password and use the information to bypass protection mechanisms.
+ Demonstrative Examples

Example 1

The following code reads a password from the user, uses the password to connect to a back-end mainframe and then attempts to scrub the password from memory using memset().

(bad)
Example Language:
void GetData(char *MFAddr) {
char pwd[64];
if (GetPasswordFromUser(pwd, sizeof(pwd))) {

if (ConnectToMainframe(MFAddr, pwd)) {
// Interaction with mainframe

}

}
memset(pwd, 0, sizeof(pwd));

}

The code in the example will behave correctly if it is executed verbatim, but if the code is compiled using an optimizing compiler, such as Microsoft Visual C++ .NET or GCC 3.x, then the call to memset() will be removed as a dead store because the buffer pwd is not used after its value is overwritten [18]. Because the buffer pwd contains a sensitive value, the application may be vulnerable to attack if the data are left memory resident. If attackers are able to access the correct region of memory, they may use the recovered password to gain control of the system.

It is common practice to overwrite sensitive data manipulated in memory, such as passwords or cryptographic keys, in order to prevent attackers from learning system secrets. However, with the advent of optimizing compilers, programs do not always behave as their source code alone would suggest. In the example, the compiler interprets the call to memset() as dead code because the memory being written to is not subsequently used, despite the fact that there is clearly a security motivation for the operation to occur. The problem here is that many compilers, and in fact many programming languages, do not take this and other security concerns into consideration in their efforts to improve efficiency.

Attackers typically exploit this type of vulnerability by using a core dump or runtime mechanism to access the memory used by a particular application and recover the secret information. Once an attacker has access to the secret information, it is relatively straightforward to further exploit the system and possibly compromise other resources with which the application interacts.

+ Potential Mitigations

Phase: Implementation

Store the sensitive data in a "volatile" memory location if available.

Phase: Build and Compilation

If possible, configure your compiler so that it does not remove dead stores.

Phase: Architecture and Design

Where possible, encrypt sensitive data that are used by a software system.
+ Detection Methods

Black Box

This specific weakness is impossible to detect using black box methods. While an analyst could examine memory to see that it has not been scrubbed, an analysis of the executable would not be successful. This is because the compiler has already removed the relevant code. Only the source code shows whether the programmer intended to clear the memory or not, so this weakness is indistinguishable from others.

White Box

This weakness is only detectable using white box methods (see black box detection factor). Careful analysis is required to determine if the code is likely to be removed by the compiler.
+ Affected Resources
  • Memory
+ Memberships
This 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.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
7 Pernicious KingdomsInsecure Compiler Optimization
PLOVERSensitive memory uncleared by compiler optimization
OWASP Top Ten 2004A8CWE More SpecificInsecure Storage
CERT C Secure CodingMSC06-CBe aware of compiler optimization when dealing with sensitive data
Software Fault PatternsSFP23Exposed Data
+ References
[REF-7] Michael Howard and David LeBlanc. "Writing Secure Code". Chapter 9, "A Compiler Optimization Caveat" Page 322. 2nd Edition. Microsoft Press. 2002-12-04. <https://www.microsoft.com/mspress/books/toc/5957.aspx>.
[REF-124] Michael Howard. "When scrubbing secrets in memory doesn't work". BugTraq. 2002-11-05. <http://cert.uni-stuttgart.de/archive/bugtraq/2002/11/msg00046.html>.
[REF-125] Michael Howard. "Some Bad News and Some Good News". Microsoft. 2002-10-21. <http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dncode/html/secure10102002.asp>.
[REF-126] Joseph Wagner. "GNU GCC: Optimizer Removes Code Necessary for Security". Bugtraq. 2002-11-16. <http://www.derkeiler.com/Mailing-Lists/securityfocus/bugtraq/2002-11/0257.html>.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
7 Pernicious Kingdoms
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Other_Notes, Taxonomy_Mappings
2008-10-14CWE Content TeamMITRE
updated Relationships
2008-11-24CWE Content TeamMITRE
updated Applicable_Platforms, Description, Detection_Factors, Other_Notes, Potential_Mitigations, Relationships, Taxonomy_Mappings, Time_of_Introduction
2009-05-27CWE Content TeamMITRE
updated Demonstrative_Examples
2010-02-16CWE Content TeamMITRE
updated References
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, References, Relationships
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2017-01-19CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated References, Relationships, Taxonomy_Mappings
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Insecure Compiler Optimization

CWE-368: Context Switching Race Condition

Weakness ID: 368
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
A product performs a series of non-atomic actions to switch between contexts that cross privilege or other security boundaries, but a race condition allows an attacker to modify or misrepresent the product's behavior during the switch.
+ Extended Description
This is commonly seen in web browser vulnerabilities in which the attacker can perform certain actions while the browser is transitioning from a trusted to an untrusted domain, or vice versa, and the browser performs the actions on one domain using the trust level and resources of the other domain.