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 (2.11)  
ID

CWE-822: Untrusted Pointer Dereference

Weakness ID: 822
Abstraction: Base
Status: Incomplete
Presentation Filter:
+ Description

Description Summary

The program obtains a value from an untrusted source, converts this value to a pointer, and dereferences the resulting pointer.

Extended Description

An attacker can supply a pointer for memory locations that the program is not expecting. If the pointer is dereferenced for a write operation, the attack might allow modification of critical program state variables, cause a crash, or execute code. If the dereferencing operation is for a read, then the attack might allow reading of sensitive data, cause a crash, or set a program variable to an unexpected value (since the value will be read from an unexpected memory location).

There are several variants of this weakness, including but not necessarily limited to:

  • The untrusted value is directly invoked as a function call.

  • In OS kernels or drivers where there is a boundary between "userland" and privileged memory spaces, an untrusted pointer might enter through an API or system call (see CWE-781 for one such example).

  • Inadvertently accepting the value from an untrusted control sphere when it did not have to be accepted as input at all. This might occur when the code was originally developed to be run by a single user in a non-networked environment, and the code is then ported to or otherwise exposed to a networked environment.

+ Terminology Notes

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.

+ Common Consequences
ScopeEffect
Confidentiality

Technical Impact: Read memory

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

Availability

Technical Impact: DoS: crash / exit / restart

If the untrusted pointer references a memory location that is not accessible to the program, or points to a location that is "malformed" or larger than expected by a read or write operation, the application may terminate unexpectedly.

Integrity
Confidentiality
Availability

Technical Impact: Execute unauthorized code or commands; Modify memory

If the untrusted 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
message-passing framework interprets values in packets as pointers, causing a crash.
labeled as a "type confusion" issue, also referred to as a "stale pointer." However, the bug ID says "contents are simply interpreted as a pointer... renderer ordinarily doesn't supply this pointer directly". The "handle" in the untrusted area is replaced in one function, but not another - thus also, effectively, exposure to wrong sphere (CWE-668).
Untrusted dereference using undocumented constructor.
An error code is incorrectly checked and interpreted as a pointer, leading to a crash.
An untrusted value is obtained from a packet and directly called as a function pointer, leading to code execution.
Undocumented attribute in multimedia software allows "unmarshaling" of an untrusted pointer.
ActiveX control for security software accepts a parameter that is assumed to be an initialized pointer.
Spreadsheet software treats certain record values that lead to "user-controlled pointer" (might be untrusted offset, not untrusted pointer).
+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness ClassWeakness Class119Improper Restriction of Operations within the Bounds of a Memory Buffer
Development Concepts (primary)699
Research Concepts (primary)1000
ChildOfCategoryCategory465Pointer Issues
Development Concepts699
ChildOfCategoryCategory8672011 Top 25 - Weaknesses On the Cusp
Weaknesses in the 2011 CWE/SANS Top 25 Most Dangerous Software Errors (primary)900
ChildOfCategoryCategory876CERT C++ Secure Coding Section 08 - Memory Management (MEM)
Weaknesses Addressed by the CERT C++ Secure Coding Standard (primary)868
CanPrecedeWeakness BaseWeakness Base125Out-of-bounds Read
Research Concepts1000
CanPrecedeWeakness BaseWeakness Base787Out-of-bounds Write
Research Concepts1000
MemberOfViewView884CWE Cross-section
CWE Cross-section (primary)884
CanFollowWeakness VariantWeakness Variant781Improper Address Validation in IOCTL with METHOD_NEITHER I/O Control Code
Development Concepts699
+ Research Gaps

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.

+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CERT C++ Secure CodingMEM10-CPPDefine and use a pointer validation function
+ Maintenance Notes

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.

+ Content History
Submissions
Submission DateSubmitterOrganizationSource
2010-09-22MITREInternal CWE Team
Modifications
Modification DateModifierOrganizationSource
2011-03-29CWE Content TeamMITREInternal
updated Description
2011-06-01CWE Content TeamMITREInternal
updated Common_Consequences
2011-06-27CWE Content TeamMITREInternal
updated Related_Attack_Patterns, Relationships
2011-09-13CWE Content TeamMITREInternal
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITREInternal
updated Relationships

More information is available — Please select a different filter.
Page Last Updated: May 05, 2017