CWE-789 Detail

The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.

Modes Of Introduction

Implementation

Applicable Platforms

Language

Name: C (Undetermined)
Name: C++ (Undetermined)
Class: Not Language-Specific (Undetermined)

Common Consequences

Observed Examples

Potential Mitigations

Phases : Implementation // Architecture and Design
Perform adequate input validation against any value that influences the amount of memory that is allocated. Define an appropriate strategy for handling requests that exceed the limit, and consider supporting a configuration option so that the administrator can extend the amount of memory to be used if necessary.
Phases : Operation
Run your program using system-provided resource limits for memory. This might still cause the program to crash or exit, but the impact to the rest of the system will be minimized.

Detection Methods

Fuzzing

Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
Effectiveness : High

Automated Static Analysis

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

Vulnerability Mapping Notes

Justification : This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comment : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

NotesNotes

This weakness can be closely associated with integer overflows (CWE-190). Integer overflow attacks would concentrate on providing an extremely large number that triggers an overflow that causes less memory to be allocated than expected. By providing a large value that does not trigger an integer overflow, the attacker could still cause excessive amounts of memory to be allocated.

Uncontrolled memory allocation is possible in many languages, such as dynamic array allocation in perl or initial size parameters in Collections in Java. However, languages like C and C++ where programmers have the power to more directly control memory management will be more susceptible.

References

REF-62

The Art of Software Security Assessment
Mark Dowd, John McDonald, Justin Schuh.

REF-962

Automated Source Code Security Measure (ASCSM)
Object Management Group (OMG).
http://www.omg.org/spec/ASCSM/1.0/

Submission

Modifications