CWE - CWE-464: Addition of Data Structure Sentinel (4.4)

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)

Nature	Type	ID	Name
ChildOf	Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.	138	Improper Neutralization of Special Elements
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	170	Improper Null Termination
PeerOf	Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	463	Deletion of Data Structure Sentinel

Relevant to the view "Software Development" (CWE-699)

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	137	Data Neutralization 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 life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

Phase	Note
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.

Scope	Impact	Likelihood
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 code)

Example Language: C

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.

Nature	Type	ID	Name
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	741	CERT C Secure Coding Standard (2008) Chapter 8 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	875	CERT C++ Secure Coding Section 07 - Characters and Strings (STR)
MemberOf	Category - a CWE entry that contains a set of other entries that share a common characteristic.	977	SFP Secondary Cluster: Design

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Mapped Node Name
CLASP		Addition of data-structure sentinel
CERT C Secure Coding	STR03-C	Do not inadvertently truncate a null-terminated byte string
CERT C Secure Coding	STR06-C	Do not assume that strtok() leaves the parse string unchanged

References

[REF-18] Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>.

Content History

Submissions
Submission Date	Submitter	Organization
2006-07-19	CLASP
2006-07-19
Modifications
Modification Date	Modifier	Organization
2008-07-01	Eric Dalci	Cigital
2008-07-01	updated Time_of_Introduction
2008-09-08	CWE Content Team	MITRE
2008-09-08	updated Applicable_Platforms, Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
2008-11-24	CWE Content Team	MITRE
2008-11-24	updated Relationships, Taxonomy_Mappings
2009-07-27	CWE Content Team	MITRE
2009-07-27	updated Demonstrative_Examples, Description, Other_Notes, Potential_Mitigations, Relationships
2011-06-01	CWE Content Team	MITRE
2011-06-01	updated Common_Consequences
2011-06-27	CWE Content Team	MITRE
2011-06-27	updated Common_Consequences
2011-09-13	CWE Content Team	MITRE
2011-09-13	updated Relationships, Taxonomy_Mappings
2012-05-11	CWE Content Team	MITRE
2012-05-11	updated Relationships
2012-10-30	CWE Content Team	MITRE
2012-10-30	updated Potential_Mitigations
2014-07-30	CWE Content Team	MITRE
2014-07-30	updated Relationships
2017-11-08	CWE Content Team	MITRE
2017-11-08	updated Demonstrative_Examples, Likelihood_of_Exploit, Taxonomy_Mappings
2020-02-24	CWE Content Team	MITRE
2020-02-24	updated References, Relationships
Previous Entry Names
Change Date	Previous Entry Name
2008-04-11	Addition of Data-structure Sentinel


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Common Weakness Enumeration

CWE-464: Addition of Data Structure Sentinel