Reliance on Data/Memory Layout

Opis

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

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.

Skutki

• Integrity, Confidentiality

  Modify Memory; Read Memory

  Can result in unintended modifications or exposure of sensitive memory.

Zapobieganie

• Implementation, Architecture and Design

  In flat address space situations, never allow computing memory addresses as offsets from another memory address.

• Architecture and Design

  Fully specify protocol layout unambiguously, providing a structured grammar (e.g., a compilable yacc grammar).

• Testing

  Testing: Test that the implementation properly handles each case in the protocol grammar.

Słabość nadrzędna

• CWE-1105 Insufficient Encapsulation of Machine-Dependent Functionality
• CWE-435 Improper Interaction Between Multiple Correctly-Behaving Entities

Słabości podrzędne

• CWE-198 Use of Incorrect Byte Ordering

Kiedy powstaje

• Implementation

Dotyczy

Not Language-Specific, C, C++

Źródła

1. The Art of Software Security Assessment — Mark Dowd, John McDonald, Justin Schuh, Chapter 6, "Structure Padding", Page 284, Addison Wesley, 2006
2. The CLASP Application Security Process — Secure Software, Inc., 2005
3. AddressSanitizer