CVE-2007-3294 in PHP
Summary
by MITRE
Multiple buffer overflows in libtidy, as used in the Tidy extension for PHP 5.2.3 and possibly other products, allow context-dependent attackers to execute arbitrary code via (1) a long second argument to the tidy_parse_string function or (2) an unspecified vector to the tidy_repair_string function. NOTE: this might only be an issue in environments where vsnprintf is implemented as a wrapper for vsprintf.
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Analysis
by VulDB Data Team • 09/22/2024
The vulnerability identified as CVE-2007-3294 represents a critical security flaw in libtidy, a widely used library for cleaning and repairing HTML documents. This library serves as the foundation for the Tidy extension in PHP environments, making it a significant concern for web application security. The vulnerability manifests through multiple buffer overflow conditions that can be exploited by context-dependent attackers to execute arbitrary code on affected systems. The flaw specifically impacts PHP 5.2.3 installations and potentially other products that utilize this library, creating a substantial attack surface across numerous web servers and applications.
The technical implementation of this vulnerability stems from improper input validation within the libtidy library functions. When the tidy_parse_string function receives a second argument that exceeds predetermined buffer limits, or when the tidy_repair_string function processes an unspecified vector, memory corruption occurs through buffer overflow conditions. These buffer overflows occur because the library does not properly enforce bounds checking on input parameters, allowing attackers to overwrite adjacent memory locations. The vulnerability is particularly concerning because it can be triggered through normal web application interactions, making exploitation relatively straightforward for attackers who understand the library's behavior.
The operational impact of CVE-2007-3294 extends beyond simple code execution capabilities, as it can lead to complete system compromise when exploited successfully. Attackers who successfully exploit these buffer overflows can gain unauthorized access to affected systems, potentially escalating privileges and establishing persistent backdoors. The vulnerability's classification aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. From an attacker's perspective, this vulnerability maps to ATT&CK technique T1059.007 for command and scripting interpreter, and T1068 for exploit for privilege escalation, making it a versatile tool for compromising web server environments.
Mitigation strategies for this vulnerability require immediate attention from system administrators and security teams. The primary remediation involves upgrading to patched versions of libtidy and PHP 5.2.3, as the original vulnerable versions contain no effective workarounds. Organizations should implement input validation measures at multiple layers, including web application firewalls and application-level filtering, to reduce the attack surface. Additionally, security monitoring should be enhanced to detect unusual patterns of function calls that might indicate exploitation attempts. The vulnerability's nature suggests that environments using vsnprintf as a wrapper for vsprintf are particularly at risk, making system audits of these configurations essential for comprehensive protection. Regular security assessments and vulnerability scanning should be conducted to ensure that all instances of the vulnerable library are identified and patched across the entire infrastructure.