CVE-2005-4083 in eXtreme Styles phpBB module
Summary
by MITRE
Directory traversal vulnerability in xs_edit.php in the eXtreme Styles phpBB module 2.2.1 and earlier allows remote attackers to read arbitrary files via a .. (dot dot) in the edit parameter.
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Analysis
by VulDB Data Team • 07/28/2017
The vulnerability identified as CVE-2005-4083 represents a critical directory traversal flaw within the eXtreme Styles phpBB module version 2.2.1 and earlier. This vulnerability exists in the xs_edit.php script which processes user input through the edit parameter without proper validation or sanitization. The flaw stems from the module's failure to adequately restrict file access paths, allowing malicious actors to exploit the application's file handling mechanisms.
The technical implementation of this vulnerability operates through a classic path traversal attack vector where an attacker can manipulate the edit parameter to include directory traversal sequences such as .. or %2e%2e. When the phpBB module processes these inputs, it fails to validate whether the requested file path remains within the intended directory boundaries. This allows an attacker to navigate outside the intended file access scope and potentially access sensitive system files that should remain protected. The vulnerability directly maps to CWE-22 which defines improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially enable attackers to access configuration files, database credentials, user information, and other sensitive data stored on the server. In a typical phpBB environment, this vulnerability could allow an attacker to read files such as config.php which contains database connection details, or other administrative files that could provide further attack vectors. The remote nature of this exploit means that attackers do not require local system access or authentication to leverage this vulnerability, making it particularly dangerous in publicly accessible web applications.
From an adversary perspective, this vulnerability aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing with Malicious Attachments) as attackers can use this flaw to gather intelligence about the target system. The exploitation process typically involves crafting a malicious URL with encoded directory traversal sequences that when executed against the vulnerable module, results in unauthorized file access. The vulnerability affects not only the specific module but potentially the entire phpBB installation since the flaw exists within the core application logic rather than being isolated to a single component.
Organizations should immediately implement mitigations including updating to the latest version of the eXtreme Styles module where this vulnerability has been patched, implementing proper input validation and sanitization mechanisms, and applying web application firewalls that can detect and block directory traversal attempts. Additionally, regular security audits should be conducted to identify similar vulnerabilities in other components of the phpBB ecosystem, as this type of flaw often indicates broader security issues within the application architecture. The vulnerability serves as a reminder of the importance of input validation and proper access control mechanisms in web applications, particularly those handling user-supplied data.