Improper Restriction of Operations within the Bounds of a Memory Buffer

Opis

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

Inne nazwy

Buffer Overflow

This term has many different meanings to different audiences. From a CWE mapping perspective, this term should be avoided where possible. Some researchers, developers, and tools intend for it to mean "write past the end of a buffer," whereas others use the same term to mean "any read or write outside the boundaries of a buffer, whether before the beginning of the buffer or after the end of the buffer." Others could mean "any action after the end of a buffer, whether it is a read or write." Since the term is commonly used for exploitation and for vulnerabilities, it further confuses things.

buffer overrun

Some prominent vendors and researchers use the term "buffer overrun," but most people use "buffer overflow." See the alternate term for "buffer overflow" for context.

memory safety

Generally used for techniques that avoid weaknesses related to memory access, such as those identified by CWE-119 and its descendants. However, the term is not formal, and there is likely disagreement between practitioners as to which weaknesses are implicitly covered by the "memory safety" term.

Skutki

• Integrity, Confidentiality, Availability

  Execute Unauthorized Code or Commands; Modify Memory

  If the memory accessible by the attacker can be effectively controlled, it may be possible to execute arbitrary code, as with a standard buffer overflow. If the attacker can overwrite a pointer's worth of memory (usually 32 or 64 bits), they can alter the intended control flow by redirecting a function pointer to their own malicious code. Even when the attacker can only modify a single byte arbitrary code execution can be possible. Sometimes this is because the same problem can be exploited repeatedly to the same effect. Other times it is because the attacker can overwrite security-critical application-specific data -- such as a flag indicating whether the user is an administrator.

• Availability, Confidentiality

  Read Memory; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)

  Out of bounds memory access will very likely result in the corruption of relevant memory, and perhaps instructions, possibly leading to a crash. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.

• Confidentiality

  Read Memory

  In the case of an out-of-bounds read, the attacker may have access to sensitive information. If the sensitive information contains system details, such as the current buffer's position in memory, this knowledge can be used to craft further attacks, possibly with more severe consequences.

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-2021-22991 Incorrect URI normalization in application traffic product leads to buffer overflow, as exploited in the wild per CISA KEV.
• CVE-2025-47153 Chain: build process for JavaScript runtime environment can have inconsistent sizes for off_t (CWE-1102), allowing out-of-bounds access / segmentation fault (CWE-119)
• CVE-2020-29557 Buffer overflow in Wi-Fi router web interface, as exploited in the wild per CISA KEV.
• 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
• CVE-2009-0689 large precision value in a format string triggers overflow
• CVE-2009-0690 negative offset value leads to out-of-bounds read
• CVE-2009-1532 malformed inputs cause accesses of uninitialized or previously-deleted objects, leading to memory corruption
• CVE-2009-1528 chain: lack of synchronization leads to memory corruption
• CVE-2021-29529 Chain: machine-learning product can have a heap-based buffer overflow (CWE-122) when some integer-oriented bounds are calculated by using ceiling() and floor() on floating point values (CWE-1339)
• CVE-2009-0558 attacker-controlled array index leads to code execution
• 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-2009-0566 chain: incorrect calculations lead to incorrect pointer dereference and memory corruption
• CVE-2009-1350 product accepts crafted messages that lead to a dereference of an arbitrary pointer
• CVE-2009-0191 chain: malformed input causes dereference of uninitialized memory
• CVE-2008-4113 OS kernel trusts userland-supplied length value, allowing reading of sensitive information
• CVE-2005-1513 Chain: integer overflow in securely-coded mail program leads to buffer overflow. In 2005, this was regarded as unrealistic to exploit, but in 2020, it was rediscovered to be easier to exploit due to evolutions of the technology.
• CVE-2003-0542 buffer overflow involving a regular expression with a large number of captures
• CVE-2017-1000121 chain: unchecked message size metadata allows integer overflow (CWE-190) leading to buffer overflow (CWE-119).

Słabość nadrzędna

• CWE-118 Incorrect Access of Indexable Resource ('Range Error')
• CWE-20 Improper Input Validation

Słabości podrzędne

• CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
• CWE-123 Write-what-where Condition
• CWE-125 Out-of-bounds Read
• CWE-130 Improper Handling of Length Parameter Inconsistency
• CWE-466 Return of Pointer Value Outside of Expected Range
• CWE-786 Access of Memory Location Before Start of Buffer
• CWE-787 Out-of-bounds Write
• CWE-788 Access of Memory Location After End of Buffer
• CWE-805 Buffer Access with Incorrect Length Value
• CWE-822 Untrusted Pointer Dereference
• CWE-823 Use of Out-of-range Pointer Offset
• CWE-824 Access of Uninitialized Pointer
• CWE-825 Expired Pointer Dereference

Kiedy powstaje

• Implementation

Dotyczy

Memory-Unsafe, C, C++, Assembly, Not Technology-Specific

Uwagi

It is possible in any programming languages without memory management support to attempt an operation outside of the bounds of a memory buffer, but the consequences will vary widely depending on the language, platform, and chip architecture.

Źródła

1. Smashing The Stack For Fun And Profit — Aleph One, Phrack, 1996
2. Writing Secure Code — Michael Howard, David LeBlanc, Chapter 5, "Public Enemy #1: The Buffer Overrun" Page 127; Chapter 14, "Prevent I18N Buffer Overruns" Page 441, Microsoft Press, 2002
3. Using the Strsafe.h Functions — Microsoft
4. Safe C String Library v1.0.3 — Matt Messier, John Viega
5. Address Space Layout Randomization in Windows Vista — Michael Howard
6. Limiting buffer overflows with ExecShield — Arjan van de Ven
7. PaX
8. Understanding DEP as a mitigation technology part 1 — Microsoft
9. The Art of Software Security Assessment — Mark Dowd, John McDonald, Justin Schuh, Chapter 5, "Memory Corruption", Page 167, Addison Wesley, 2006
10. Position Independent Executables (PIE) — Grant Murphy, Red Hat, 2012
11. Prelink and address space randomization — John Richard Moser, 2006
12. Jump Over ASLR: Attacking Branch Predictors to Bypass ASLR — Dmitry Evtyushkin, Dmitry Ponomarev, Nael Abu-Ghazaleh, 2016
13. Stack Frame Canary Validation (D3-SFCV) — D3FEND, 2023
14. Segment Address Offset Randomization (D3-SAOR) — D3FEND, 2023
15. Process Segment Execution Prevention (D3-PSEP) — D3FEND, 2023
16. Bypassing Browser Memory Protections: Setting back browser security by 10 years — Alexander Sotirov and Mark Dowd, Memory information leaks, 2008
17. Secure by Design Alert: Eliminating Buffer Overflow Vulnerabilities — Cybersecurity and Infrastructure Security Agency, 2025
18. State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation — Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler, Rama S. Moorthy, 2014
19. AddressSanitizer