CVE-2005-4084 in phpBB eXtreme Styles
Summary
by MITRE
xs_edit.php in the phpBB eXtreme Styles module 2.2.1 and earlier allows remote attackers to obtain the installation path of the application via an invalid viewbackup parameter.
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Analysis
by VulDB Data Team • 07/26/2017
The vulnerability identified as CVE-2005-4084 affects the phpBB eXtreme Styles module version 2.2.1 and earlier, representing a significant information disclosure flaw that exposes sensitive installation path details to remote attackers. This vulnerability specifically resides within the xs_edit.php script, which is part of the phpBB community forum software ecosystem. The issue manifests when an attacker manipulates the viewbackup parameter to invalid values, triggering an error message that inadvertently reveals the absolute file system path where the phpBB installation resides. Such information disclosure represents a critical security risk as it provides attackers with precise knowledge of the server's file structure and installation location, enabling more sophisticated attack vectors.
The technical exploitation of this vulnerability occurs through parameter manipulation techniques that leverage the module's error handling mechanisms. When the viewbackup parameter receives invalid input, the application fails to properly sanitize or validate the input before processing it, resulting in an error message that contains the full server path. This behavior aligns with CWE-200, which catalogs information exposure vulnerabilities where systems inadvertently disclose sensitive information through error messages or debug output. The flaw demonstrates poor input validation practices and inadequate error handling within the phpBB module, creating an attack surface that can be exploited by malicious actors without requiring authentication or advanced privileges.
From an operational impact perspective, this vulnerability significantly weakens the security posture of affected systems by providing attackers with crucial reconnaissance information. The disclosed installation path enables attackers to craft more targeted attacks, including directory traversal exploits, file inclusion vulnerabilities, and other path-based attacks that rely on knowledge of the system's file structure. The vulnerability also supports broader reconnaissance efforts that can lead to privilege escalation, data exfiltration, or system compromise. Security professionals should note that this information disclosure can be particularly dangerous in environments where multiple applications share similar directory structures or where the disclosed paths contain sensitive configuration information.
The attack surface for this vulnerability extends beyond simple path disclosure, as it can facilitate cascading security issues that compound the initial exposure. Attackers can use the discovered installation paths to map application dependencies, identify version-specific vulnerabilities, and potentially exploit other weaknesses within the same system. This vulnerability aligns with several ATT&CK techniques including T1083 (File and Directory Discovery) and T1068 (Exploitation for Privilege Escalation), demonstrating how information disclosure can serve as a foundational step for more sophisticated attacks. Organizations should consider this vulnerability as part of a broader threat landscape where initial reconnaissance information can be leveraged to execute more complex attack chains. The remediation approach should focus on implementing proper input validation, sanitizing error messages to prevent path disclosure, and ensuring that all module components properly handle invalid parameters without exposing system information.
Mitigation strategies for CVE-2005-4084 should include immediate patching of the affected phpBB eXtreme Styles module to version 2.2.2 or later, which contains the necessary fixes for this vulnerability. Organizations should also implement comprehensive input validation across all application parameters, particularly those that handle user-supplied data. Error handling should be reviewed to ensure that system paths and sensitive information are never exposed in error messages, aligning with security best practices outlined in OWASP Top Ten and NIST cybersecurity guidelines. Additionally, organizations should conduct regular security assessments of their phpBB installations to identify and remediate similar information disclosure vulnerabilities that may exist in other modules or components of the application ecosystem.