CWE-806 詳細

The product uses the size of a source buffer when reading from or writing to a destination buffer, which may cause it to access memory that is outside of the bounds of the buffer.

導入モード

Implementation

適用可能なプラットフォーム

言語

クラス： Memory-Unsafe (Undetermined)
名前： C (Sometimes)
名前： C++ (Sometimes)

一般的な結果

潜在的な緩和策

Phases : Architecture and Design
Use an abstraction library to abstract away risky APIs. Examples include the Safe C String Library (SafeStr) by Viega, and the Strsafe.h library from Microsoft. This is not a complete solution, since many buffer overflows are not related to strings.
Phases : Operation // Build and Compilation
Phases : Implementation
Programmers should adhere to the following rules when allocating and managing their applications memory: Double check that your buffer is as large as you specify. 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 calling this function in a loop and make sure there is no danger of writing past the allocated space. Truncate all input strings to a reasonable length before passing them to the copy and concatenation functions.
Phases : Operation // Build and Compilation
Phases : Operation
Phases : Build and Compilation // Operation
Most mitigating technologies at the compiler or OS level to date address only a subset of buffer overflow problems and rarely provide complete protection against even that subset. It is good practice to implement strategies to increase the workload of an attacker, such as leaving the attacker to guess an unknown value that changes every program execution.

検出方法

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
有効性 : High

Automated Dynamic Analysis

Use tools that are integrated during compilation to insert runtime error-checking mechanisms related to memory safety errors, such as AddressSanitizer (ASan) for C/C++ [REF-1518].
有効性 : Moderate

脆弱性マッピングノート

理由 : This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
コメント : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

参考文献

REF-56

Using the Strsafe.h Functions
Microsoft.
https://learn.microsoft.com/en-us/windows/win32/menurc/strsafe-ovw?redirectedfrom=MSDN

REF-57

Safe C String Library v1.0.3
Matt Messier, John Viega.
http://www.gnu-darwin.org/www001/ports-1.5a-CURRENT/devel/safestr/work/safestr-1.0.3/doc/safestr.html

REF-58

Address Space Layout Randomization in Windows Vista
Michael Howard.
https://learn.microsoft.com/en-us/archive/blogs/michael_howard/address-space-layout-randomization-in-windows-vista

REF-59

Limiting buffer overflows with ExecShield
Arjan van de Ven.
https://archive.is/saAFo

REF-60

PaX
https://en.wikipedia.org/wiki/Executable_space_protection#PaX

REF-61

Understanding DEP as a mitigation technology part 1
Microsoft.
https://msrc.microsoft.com/blog/2009/06/understanding-dep-as-a-mitigation-technology-part-1/

REF-64

Position Independent Executables (PIE)
Grant Murphy.
https://www.redhat.com/en/blog/position-independent-executables-pie

REF-1332

Prelink and address space randomization
John Richard Moser.
https://lwn.net/Articles/190139/

REF-1333

Jump Over ASLR: Attacking Branch Predictors to Bypass ASLR
Dmitry Evtyushkin, Dmitry Ponomarev, Nael Abu-Ghazaleh.
http://www.cs.ucr.edu/~nael/pubs/micro16.pdf

REF-1334

Stack Frame Canary Validation (D3-SFCV)
D3FEND.
https://d3fend.mitre.org/technique/d3f:StackFrameCanaryValidation/

REF-1335

Segment Address Offset Randomization (D3-SAOR)
D3FEND.
https://d3fend.mitre.org/technique/d3f:SegmentAddressOffsetRandomization/

REF-1336

Process Segment Execution Prevention (D3-PSEP)
D3FEND.
https://d3fend.mitre.org/technique/d3f:ProcessSegmentExecutionPrevention/

REF-1337

Bypassing Browser Memory Protections: Setting back browser security by 10 years
Alexander Sotirov and Mark Dowd.
https://www.blackhat.com/presentations/bh-usa-08/Sotirov_Dowd/bh08-sotirov-dowd.pdf

REF-1518

AddressSanitizer
https://clang.llvm.org/docs/AddressSanitizer.html

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