CWE-188

Reliance on Data/Memory Layout
AI Translation Available

The product makes invalid assumptions about how protocol data or memory is organized at a lower level, resulting in unintended program behavior.

Status
draft
Abstraction
base
Likelihood
low
C C++ Not Language-Specific

When changing platforms or protocol versions, in-memory organization of data may change in unintended ways. For example, some architectures may place local variables A and B right next to each other with A on top; some may place them next to each other with B on top; and others may add some padding to each. The padding size may vary to ensure that each variable is aligned to a proper word size.

In protocol implementations, it is common to calculate an offset relative to another field to pick out a specific piece of data. Exceptional conditions, often involving new protocol versions, may add corner cases that change the data layout in an unusual way. The result can be that an implementation accesses an unintended field in the packet, treating data of one type as data of another type.

Common Consequences

integrity confidentiality
Impacts
modify memory read memory

Detection Methods

fuzzing automated dynamic analysis

Potential Mitigations

Phases:
implementation architecture and design testing
Descriptions:
• Fully specify protocol layout unambiguously, providing a structured grammar (e.g., a compilable yacc grammar).
• In flat address space situations, never allow computing memory addresses as offsets from another memory address.
• Testing: Test that the implementation properly handles each case in the protocol grammar.

Functional Areas

memory management