Out-of-bounds Write

Opis

The product writes data past the end, or before the beginning, of the intended buffer.

Inne nazwy

Memory Corruption

Often used to describe the consequences of writing to memory outside the bounds of a buffer, or to memory that is otherwise invalid.

Skutki

• Integrity

  Modify Memory; Execute Unauthorized Code or Commands

  Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.

• Availability

  DoS: Crash, Exit, or Restart

  Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.

• Other

  Unexpected State

  Subsequent write operations can produce undefined or unexpected results.

Zapobieganie

• Requirements · Language Selection

  Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

  For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer.

  Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.

• Architecture and Design · Libraries or Frameworks

  Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

  Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions.

• Operation, Build and Compilation · Environment Hardening

  Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.

  D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.

  Skuteczność: Defense in Depth

• Implementation

  Consider adhering to the following rules when allocating and managing an application's memory:

  - Double check that the buffer is as large as specified.

  - When using functions that accept a number of bytes to copy, such as strncpy(), be aware that if the destination buffer size is equal to the source buffer size, it may not NULL-terminate the string.

  - Check buffer boundaries if accessing the buffer in a loop and make sure there is no danger of writing past the allocated space.

  - If necessary, truncate all input strings to a reasonable length before passing them to the copy and concatenation functions.

• Operation, Build and Compilation · Environment Hardening

  Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.

  Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.

  For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].

  Skuteczność: Defense in Depth

• Operation · Environment Hardening

  Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.

  For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].

  Skuteczność: Defense in Depth

• Implementation

  Replace unbounded copy functions with analogous functions that support length arguments, such as strcpy with strncpy. Create these if they are not available.

  Skuteczność: Moderate

Przykłady podatności

• CVE-2025-27363 Font rendering library does not properly handle assigning a signed short value to an unsigned long (CWE-195), leading to an integer wraparound (CWE-190), causing too small of a buffer (CWE-131), leading to an out-of-bounds write (CWE-787).
• CVE-2023-1017 The reference implementation code for a Trusted Platform Module does not implement length checks on data, allowing for an attacker to write 2 bytes past the end of a buffer.
• CVE-2021-21220 Chain: insufficient input validation (CWE-20) in browser allows heap corruption (CWE-787), as exploited in the wild per CISA KEV.
• CVE-2021-28664 GPU kernel driver allows memory corruption because a user can obtain read/write access to read-only pages, as exploited in the wild per CISA KEV.
• CVE-2020-17087 Chain: integer truncation (CWE-197) causes small buffer allocation (CWE-131) leading to out-of-bounds write (CWE-787) in kernel pool, as exploited in the wild per CISA KEV.
• CVE-2020-1054 Out-of-bounds write in kernel-mode driver, as exploited in the wild per CISA KEV.
• CVE-2020-0041 Escape from browser sandbox using out-of-bounds write due to incorrect bounds check, as exploited in the wild per CISA KEV.
• CVE-2020-0968 Memory corruption in web browser scripting engine, as exploited in the wild per CISA KEV.
• CVE-2020-0022 chain: mobile phone Bluetooth implementation does not include offset when calculating packet length (CWE-682), leading to out-of-bounds write (CWE-787)
• CVE-2019-1010006 Chain: compiler optimization (CWE-733) removes or modifies code used to detect integer overflow (CWE-190), allowing out-of-bounds write (CWE-787).
• CVE-2009-1532 malformed inputs cause accesses of uninitialized or previously-deleted objects, leading to memory corruption
• CVE-2009-0269 chain: -1 value from a function call was intended to indicate an error, but is used as an array index instead.
• CVE-2002-2227 Unchecked length of SSLv2 challenge value leads to buffer underflow.
• CVE-2007-4580 Buffer underflow from a small size value with a large buffer (length parameter inconsistency, CWE-130)
• CVE-2007-4268 Chain: integer signedness error (CWE-195) passes signed comparison, leading to heap overflow (CWE-122)
• CVE-2009-2550 Classic stack-based buffer overflow in media player using a long entry in a playlist
• CVE-2009-2403 Heap-based buffer overflow in media player using a long entry in a playlist

Słabość nadrzędna

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

Słabości podrzędne

• CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
• CWE-121 Stack-based Buffer Overflow
• CWE-122 Heap-based Buffer Overflow
• CWE-123 Write-what-where Condition
• CWE-124 Buffer Underwrite ('Buffer Underflow')

Kiedy powstaje

• Implementation

Dotyczy

Memory-Unsafe, C, C++, Assembly, ICS/OT

Źródła

1. Smashing The Stack For Fun And Profit — Aleph One, Phrack, 1996
2. Writing Secure Code — Michael Howard, David LeBlanc, Chapter 5, "Stack Overruns" Page 129, Microsoft Press, 2002
3. Writing Secure Code — Michael Howard, David LeBlanc, Chapter 5, "Heap Overruns" Page 138, Microsoft Press, 2002
4. 24 Deadly Sins of Software Security — Michael Howard, David LeBlanc, John Viega, "Sin 5: Buffer Overruns." Page 89, McGraw-Hill, 2010
5. The Art of Software Security Assessment — Mark Dowd, John McDonald, Justin Schuh, Chapter 3, "Nonexecutable Stack", Page 76, Addison Wesley, 2006
6. The Art of Software Security Assessment — Mark Dowd, John McDonald, Justin Schuh, Chapter 5, "Protection Mechanisms", Page 189, Addison Wesley, 2006
7. Buffer UNDERFLOWS: What do you know about it? — Vuln-Dev Mailing List, 2004
8. Using the Strsafe.h Functions — Microsoft
9. Safe C String Library v1.0.3 — Matt Messier, John Viega
10. Address Space Layout Randomization in Windows Vista — Michael Howard
11. PaX
12. Understanding DEP as a mitigation technology part 1 — Microsoft
13. Position Independent Executables (PIE) — Grant Murphy, Red Hat, 2012
14. Prelink and address space randomization — John Richard Moser, 2006
15. Jump Over ASLR: Attacking Branch Predictors to Bypass ASLR — Dmitry Evtyushkin, Dmitry Ponomarev, Nael Abu-Ghazaleh, 2016
16. Stack Frame Canary Validation (D3-SFCV) — D3FEND, 2023
17. Segment Address Offset Randomization (D3-SAOR) — D3FEND, 2023
18. Process Segment Execution Prevention (D3-PSEP) — D3FEND, 2023
19. Bypassing Browser Memory Protections: Setting back browser security by 10 years — Alexander Sotirov and Mark Dowd, Memory information leaks, 2008
20. Secure by Design Alert: Eliminating Buffer Overflow Vulnerabilities — Cybersecurity and Infrastructure Security Agency, 2025
21. AddressSanitizer