CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
Home > CWE List > CWE- Individual Dictionary Definition (3.0)  
ID

CWE-125: Out-of-bounds Read

Weakness ID: 125
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The software reads data past the end, or before the beginning, of the intended buffer.
+ Extended Description
This typically occurs when the pointer or its index is incremented or decremented to a position beyond the bounds of the buffer or when pointer arithmetic results in a position outside of the valid memory location to name a few. This may result in corruption of sensitive information, a crash, or code execution among other things.
+ 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
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
Confidentiality

Technical Impact: Read Memory

+ Demonstrative Examples

Example 1

In the following code, the method retrieves a value from an array at a specific array index location that is given as an input parameter to the method

(bad code)
Example Language:
int getValueFromArray(int *array, int len, int index) {

int value;
// check that the array index is less than the maximum
// length of the array

if (index < len) {
// get the value at the specified index of the array

value = array[index];

}
// if array index is invalid then output error message
// and return value indicating error

else {
printf("Value is: %d\n", array[index]);
value = -1;

}

return value;

}

However, this method only verifies that the given array index is less than the maximum length of the array but does not check for the minimum value (CWE-839). This will allow a negative value to be accepted as the input array index, which will result in a out of bounds read (CWE-125) and may allow access to sensitive memory. The input array index should be checked to verify that is within the maximum and minimum range required for the array (CWE-129). In this example the if statement should be modified to include a minimum range check, as shown below.

(good code)
Example Language:

...
// check that the array index is within the correct
// range of values for the array

if (index >= 0 && index < len) {

...
+ Observed Examples
ReferenceDescription
Chain: product does not handle when an input string is not NULL terminated (CWE-170), leading to buffer over-read (CWE-125) or heap-based buffer overflow (CWE-122).
out-of-bounds read due to improper length check
packet with large number of specified elements cause out-of-bounds read.
packet with large number of specified elements cause out-of-bounds read.
out-of-bounds read, resultant from integer underflow
large length value causes out-of-bounds read
malformed image causes out-of-bounds read
+ 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

Research Gap

Under-studied and under-reported. Most issues are probably labeled as buffer overflows.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVEROut-of-bounds Read
Software Fault PatternsSFP8Faulty Buffer Access
CERT C Secure CodingARR30-CImpreciseDo not form or use out-of-bounds pointers or array subscripts
CERT C Secure CodingARR38-CImpreciseGuarantee that library functions do not form invalid pointers
CERT C Secure CodingEXP39-CImpreciseDo not access a variable through a pointer of an incompatible type
CERT C Secure CodingSTR31-CImpreciseGuarantee that storage for strings has sufficient space for character data and the null terminator
CERT C Secure CodingSTR32-CCWE More AbstractDo not pass a non-null-terminated character sequence to a library function that expects a string
+ References
[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 DateSubmitterOrganization
PLOVER
Modifications
Modification DateModifierOrganization
2008-09-08CWE Content TeamMITRE
updated Applicable_Platforms, Relationships, Taxonomy_Mappings, Weakness_Ordinalities
2009-10-29CWE Content TeamMITRE
updated Description
2010-09-27CWE Content TeamMITRE
updated Relationships
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Demonstrative_Examples, References, Relationships
2014-06-23CWE Content TeamMITRE
updated Related_Attack_Patterns
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Causal_Nature, Observed_Examples, Taxonomy_Mappings

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Page Last Updated: January 18, 2018