CVE-2008-0674 in Mac OS X
Summary
by MITRE
Buffer overflow in PCRE before 7.6 allows remote attackers to execute arbitrary code via a regular expression containing a character class with a large number of characters with Unicode code points greater than 255.
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Analysis
by VulDB Data Team • 08/05/2019
The vulnerability identified as CVE-2008-0674 represents a critical buffer overflow flaw within the Perl Compatible Regular Expressions library version 7.5 and earlier. This issue affects systems that utilize PCRE for pattern matching operations, particularly in applications that process untrusted user input through regular expression parsing. The vulnerability stems from inadequate bounds checking during the processing of character classes within regular expressions, creating a condition where maliciously crafted patterns can overflow allocated memory buffers.
The technical exploitation of this vulnerability occurs when a regular expression contains a character class with an excessive number of characters possessing Unicode code points exceeding 255. During the compilation phase of such patterns, the PCRE library fails to properly validate the size of character classes, leading to memory corruption when the buffer allocated for Unicode character handling exceeds its intended capacity. This flaw falls under the CWE-121 CWE category, specifically addressing buffer overflow conditions where insufficient bounds checking allows attackers to write beyond allocated memory regions. The vulnerability demonstrates characteristics of CWE-787, which describes out-of-bounds write conditions that can result in arbitrary code execution.
The operational impact of CVE-2008-0674 extends across numerous applications and systems that rely on PCRE for text processing and pattern matching functionality. Web applications, network intrusion detection systems, and security tools that utilize regular expressions for input validation, log parsing, or content filtering become vulnerable to remote code execution attacks. Attackers can craft malicious regular expressions that, when processed by vulnerable systems, trigger the buffer overflow condition and potentially gain control over the affected system. This vulnerability aligns with ATT&CK technique T1059.007, which covers the use of regular expressions for command injection and input manipulation attacks.
Mitigation strategies for this vulnerability require immediate patching of PCRE libraries to version 7.6 or later, where the buffer overflow has been addressed through enhanced bounds checking and proper memory allocation handling. System administrators should implement input validation measures that limit the complexity and length of regular expressions processed by applications. Additionally, deploying intrusion prevention systems that can detect and block malicious regular expression patterns represents a defensive approach. Organizations should also consider implementing application sandboxing and privilege separation techniques to limit the potential damage from successful exploitation attempts. The vulnerability demonstrates the importance of proper memory management in security-critical libraries and underscores the necessity of comprehensive testing for boundary conditions in Unicode processing components.