CVE-2008-2666 in PHP
Summary
by MITRE
Multiple directory traversal vulnerabilities in PHP 5.2.6 and earlier allow context-dependent attackers to bypass safe_mode restrictions by creating a subdirectory named http: and then placing ../ (dot dot slash) sequences in an http URL argument to the (1) chdir or (2) ftok function.
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Analysis
by VulDB Data Team • 03/01/2025
The vulnerability identified as CVE-2008-2666 represents a critical directory traversal flaw affecting PHP versions 5.2.6 and earlier, specifically targeting the safe_mode restriction mechanisms that were designed to prevent unauthorized file system access. This vulnerability operates through a sophisticated attack vector that exploits the interaction between directory naming conventions and URL parsing within PHP's file system functions. The flaw enables attackers to circumvent security controls by leveraging a specific directory naming pattern combined with conventional directory traversal sequences.
The technical implementation of this vulnerability relies on the creation of a subdirectory named "http:" which, when combined with the ../ (dot dot slash) sequences in HTTP URL arguments, allows attackers to manipulate the path resolution behavior of the chdir and ftok functions. The vulnerability stems from insufficient input validation and path sanitization within these specific PHP functions, where the system fails to properly normalize or validate the presence of directory traversal sequences in URL arguments. This creates an exploitable condition where the safe_mode restrictions, which are intended to limit file system access to specific directories, can be bypassed through carefully crafted directory structures and URL parameters.
From an operational impact perspective, this vulnerability presents a significant risk to web applications running vulnerable PHP versions, as it allows attackers to potentially access files outside the intended document root or restricted directories. The attack requires contextual knowledge of the target system's directory structure and the ability to create specific subdirectories, but once exploited, it could enable unauthorized file access, directory listing, and potentially code execution depending on the application's configuration and the attacker's privileges. The vulnerability affects the fundamental security model of PHP's safe_mode implementation, undermining the trust model that developers rely on for protecting sensitive system resources.
The attack pattern described in this vulnerability aligns with common exploitation techniques documented in the attack framework, particularly those targeting file system access controls and privilege escalation. This flaw demonstrates a weakness in the secure coding practices for URL and path handling, where the system does not adequately validate or sanitize input parameters before processing them through file system functions. The vulnerability is categorized under CWE-22, which addresses Improper Limitation of a Pathname to a Restricted Directory, and represents a specific instance of path traversal attacks that have been extensively documented in security literature and attack frameworks. Organizations affected by this vulnerability should immediately implement mitigations including upgrading to PHP versions 5.2.7 or later, where this specific issue has been patched, and implementing additional input validation measures to prevent similar patterns of exploitation. The fix typically involves stricter path normalization and validation within the affected functions, ensuring that directory traversal sequences are properly detected and rejected during URL parameter processing.