CWE-134

Use of Externally-Controlled Format String
AI Translation Available

The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

Status
draft
Abstraction
base
Likelihood
high
C C++ Not Language-Specific Perl

Common Consequences

confidentiality integrity availability
Impacts
read memory modify memory execute unauthorized code or commands

Detection Methods

automated static analysis black box automated static analysis - binary or bytecode manual static analysis - binary or bytecode dynamic analysis with automated results interpretation dynamic analysis with manual results interpretation manual static analysis - source code automated static analysis - source code architecture or design review

Potential Mitigations

Phases:
requirements implementation build and compilation
Descriptions:
• Choose a language that is not subject to this flaw.
• Run compilers and linkers with high warning levels, since they may detect incorrect usage.
• Ensure that all format string functions are passed a static string which cannot be controlled by the user, and that the proper number of arguments are always sent to that function as well. If at all possible, use functions that do not support the %n operator in format strings. [REF-116] [REF-117]

Functional Areas

logging error handling string processing memory management