CWE-134: Use of Externally-Controlled Format String
Description
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
- Abstraction
- BaseA weakness specific enough to point to detection and prevention methods.
- Likelihood of exploit
- High
- Status
- Draft
Common consequences
- Confidentiality
Read Memory
Format string problems allow for information disclosure which can severely simplify exploitation of the program.
- IntegrityConfidentialityAvailability
Modify Memory; Execute Unauthorized Code or Commands
Format string problems can result in the execution of arbitrary code, buffer overflows, denial of service, or incorrect data representation.
Potential mitigations
- Requirements
Choose a language that is not subject to this flaw.
- Implementation
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.
- Build and Compilation
Run compilers and linkers with high warning levels, since they may detect incorrect usage.