Use of Out-of-range Pointer Offset

Opis

The product performs pointer arithmetic on a valid pointer, but it uses an offset that can point outside of the intended range of valid memory locations for the resulting pointer.

While a pointer can contain a reference to any arbitrary memory location, a program typically only intends to use the pointer to access limited portions of memory, such as contiguous memory used to access an individual array.

Programs may use offsets in order to access fields or sub-elements stored within structured data. The offset might be out-of-range if it comes from an untrusted source, is the result of an incorrect calculation, or occurs because of another error.

If an attacker can control or influence the offset so that it points outside of the intended boundaries of the structure, then the attacker may be able to read or write to memory locations that are used elsewhere in the product. As a result, the attack might change the state of the product as accessed through program variables, cause a crash or instable behavior, and possibly lead to code execution.

Inne nazwy

Untrusted pointer offset

This term is narrower than the concept of "out-of-range" offset, since the offset might be the result of a calculation or other error that does not depend on any externally-supplied values.

Skutki

• Confidentiality

  Read Memory

  If the untrusted pointer is used in a read operation, an attacker might be able to read sensitive portions of memory.

• Availability

  DoS: Crash, Exit, or Restart

  If the untrusted pointer references a memory location that is not accessible to the program, or points to a location that is "malformed" or larger than expected by a read or write operation, the application may terminate unexpectedly.

• Integrity, Confidentiality, Availability

  Execute Unauthorized Code or Commands; Modify Memory

  If the untrusted pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.

Przykłady podatności

• CVE-2010-2160 Invalid offset in undocumented opcode leads to memory corruption.
• CVE-2010-1281 Multimedia player uses untrusted value from a file when using file-pointer calculations.
• CVE-2009-3129 Spreadsheet program processes a record with an invalid size field, which is later used as an offset.
• CVE-2009-2694 Instant messaging library does not validate an offset value specified in a packet.
• CVE-2009-2687 Language interpreter does not properly handle invalid offsets in JPEG image, leading to out-of-bounds memory access and crash.
• CVE-2009-0690 negative offset leads to out-of-bounds read
• CVE-2008-4114 untrusted offset in kernel
• CVE-2010-2873 "blind trust" of an offset value while writing heap memory allows corruption of function pointer,leading to code execution
• CVE-2010-2866 negative value (signed) causes pointer miscalculation
• CVE-2010-2872 signed values cause incorrect pointer calculation
• CVE-2007-5657 values used as pointer offsets
• CVE-2010-2867 a return value from a function is sign-extended if the value is signed, then used as an offset for pointer arithmetic
• CVE-2009-1097 portions of a GIF image used as offsets, causing corruption of an object pointer.
• CVE-2008-1807 invalid numeric field leads to a free of arbitrary memory locations, then code execution.
• CVE-2007-2500 large number of elements leads to a free of an arbitrary address
• CVE-2008-1686 array index issue (CWE-129) with negative offset, used to dereference a function pointer
• CVE-2010-2878 "buffer seek" value - basically an offset?

Słabość nadrzędna

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

Może prowadzić do

• CWE-125 Out-of-bounds Read
• CWE-787 Out-of-bounds Write

Kiedy powstaje

• Implementation

Dotyczy

Memory-Unsafe, C, C++

Uwagi

There are close relationships between incorrect pointer dereferences and other weaknesses related to buffer operations. There may not be sufficient community agreement regarding these relationships. Further study is needed to determine when these relationships are chains, composites, perspective/layering, or other types of relationships. As of September 2010, most of the relationships are being captured as chains.

Many weaknesses related to pointer dereferences fall under the general term of "memory corruption" or "memory safety." As of September 2010, there is no commonly-used terminology that covers the lower-level variants.

Źródła

1. The Art of Software Security Assessment — Mark Dowd, John McDonald, Justin Schuh, Chapter 6, "Pointer Arithmetic", Page 277, Addison Wesley, 2006
2. AddressSanitizer