CVE-2006-2134 in PHPbb
Summary
by MITRE
PHP remote file inclusion vulnerability in /includes/kb_constants.php in Knowledge Base Mod for PHPbb 2.0.2 and earlier allows remote attackers to execute arbitrary PHP code via a URL in the module_root_path parameter.
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Analysis
by VulDB Data Team • 06/23/2024
The vulnerability identified as CVE-2006-2134 represents a critical remote file inclusion flaw within the Knowledge Base Mod for PHPbb version 2.0.2 and earlier. This issue resides in the kb_constants.php file where the application fails to properly validate user input before incorporating it into file inclusion operations. The vulnerability specifically affects the module_root_path parameter which is susceptible to manipulation by remote attackers seeking to execute arbitrary PHP code on the target system. The flaw demonstrates characteristics consistent with CWE-98, which describes improper file inclusion vulnerabilities where attacker-controllable input is used to determine which files to include or execute. This vulnerability directly enables attackers to leverage the application's file inclusion mechanism to load and execute malicious code from remote servers, potentially leading to complete system compromise.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious URL and passes it as the module_root_path parameter to the vulnerable application. The application processes this input without adequate sanitization or validation, allowing the remote file inclusion to proceed. This type of vulnerability falls under the ATT&CK framework's technique T1505.003 for "Server-side Include", where adversaries leverage server-side code execution vulnerabilities to inject and execute malicious payloads. The attack vector requires minimal privileges as the vulnerability exists within the application's legitimate file inclusion functionality, making it particularly dangerous as it can be exploited through normal web application usage patterns without requiring elevated system access.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and data breach potential. An attacker who successfully exploits this vulnerability can gain unauthorized access to the web server, potentially leading to privilege escalation, data exfiltration, and persistence mechanisms. The vulnerability affects not just the specific knowledge base module but the entire PHPbb application ecosystem, as the flaw exists within core application functionality that is likely to be present across multiple installations. This creates a widespread risk profile where thousands of vulnerable systems could be compromised simultaneously, particularly given the popularity of PHPbb forums at the time of this vulnerability's discovery.
Mitigation strategies for CVE-2006-2134 require immediate implementation of multiple defensive measures to protect against exploitation attempts. The primary recommendation involves upgrading to a patched version of the Knowledge Base Mod for PHPbb, as this vulnerability was addressed in subsequent releases. Additionally, administrators should implement input validation and sanitization measures to prevent malicious URLs from being processed within the module_root_path parameter. Network-level protections such as web application firewalls and intrusion prevention systems can help detect and block exploitation attempts by monitoring for suspicious URL patterns in the affected parameter. The implementation of PHP's safe_mode and open_basedir restrictions can provide additional layers of protection by limiting file access to specific directories, thereby preventing unauthorized file inclusion operations. Organizations should also conduct thorough vulnerability assessments to identify all potentially affected installations and implement proper access controls to minimize the attack surface. This vulnerability highlights the importance of input validation and the principle of least privilege in web application security, demonstrating how a single unvalidated parameter can lead to complete system compromise.