Access of Resource Using Incompatible Type ('Type Confusion')

Opis

The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

When the product accesses the resource using an incompatible type, this could trigger logical errors because the resource does not have expected properties. In languages without memory safety, such as C and C++, type confusion can lead to out-of-bounds memory access.

While this weakness is frequently associated with unions when parsing data with many different embedded object types in C, it can be present in any application that can interpret the same variable or memory location in multiple ways.

This weakness is not unique to C and C++. For example, errors in PHP applications can be triggered by providing array parameters when scalars are expected, or vice versa. Languages such as Perl, which perform automatic conversion of a variable of one type when it is accessed as if it were another type, can also contain these issues.

Inne nazwy

Object Type Confusion

Skutki

• Availability, Integrity, Confidentiality

  Read Memory; Modify Memory; Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart

  When a memory buffer is accessed using the wrong type, it could read or write memory out of the bounds of the buffer, if the allocated buffer is smaller than the type that the code is attempting to access, leading to a crash and possibly code execution.

Przykłady podatności

• CVE-2025-32352 Type confusion in PHP app allows authentication bypass when users have passwords whose MD5 hashes can be interpreted as numbers
• CVE-2010-4577 Type confusion in CSS sequence leads to out-of-bounds read.
• CVE-2011-0611 Size inconsistency allows code execution, first discovered when it was actively exploited in-the-wild.
• CVE-2010-0258 Improperly-parsed file containing records of different types leads to code execution when a memory location is interpreted as a different object than intended.

Słabość nadrzędna

• CWE-704 Incorrect Type Conversion or Cast

Może prowadzić do

• CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

Kiedy powstaje

• Implementation

Dotyczy

C, C++

Uwagi

This weakness is possible in any type-unsafe programming language.

Type confusion weaknesses have received some attention by applied researchers and major software vendors for C and C++ code. Some publicly-reported vulnerabilities probably have type confusion as a root-cause weakness, but these may be described as "memory corruption" instead.

For other languages, there are very few public reports of type confusion weaknesses. These are probably under-studied. Since many programs rely directly or indirectly on loose typing, a potential "type confusion" behavior might be intentional, possibly requiring more manual analysis.

Źródła

1. Attacking Interoperability — Mark Dowd, Ryan Smith, David Dewey, "Type Confusion Vulnerabilities," page 59, 2009
2. The Art of Software Security Assessment — Mark Dowd, John McDonald, Justin Schuh, Chapter 7, "Type Confusion", Page 319, Addison Wesley, 2006