CVE-2006-2151 in phpBB TopList
Summary
by MITRE
PHP remote file inclusion vulnerability in toplist.php in phpBB TopList 1.3.8 and earlier, when register_globals is enabled, allows remote attackers to include arbitrary files via the phpbb_root_path parameter.
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Analysis
by VulDB Data Team • 06/23/2024
The vulnerability identified as CVE-2006-2151 represents a critical remote file inclusion flaw within the phpBB TopList module version 1.3.8 and earlier. This security weakness specifically targets the toplist.php script and exploits a fundamental configuration issue related to the register_globals directive in php environments. The vulnerability operates under the Common Weakness Enumeration classification of CWE-97, which encompasses improper use of potentially dangerous functions in web applications. When the register_globals setting is enabled on a php server, it automatically converts HTTP request variables into global variables, creating a dangerous environment where user-supplied input can directly influence script execution flow.
The technical exploitation of this vulnerability occurs through manipulation of the phpbb_root_path parameter within the toplist.php script. Attackers can inject malicious file paths that get included and executed by the vulnerable application, effectively allowing remote code execution capabilities. This occurs because the application fails to properly validate or sanitize the phpbb_root_path parameter before using it in file inclusion operations. The flaw essentially allows an attacker to bypass normal access controls and execute arbitrary code on the target server, potentially leading to complete system compromise. This vulnerability directly relates to the ATT&CK technique T1059.007 for remote code execution through web shells and command injection.
The operational impact of this vulnerability extends beyond simple data theft or service disruption. When successfully exploited, attackers can gain full administrative control over the affected web server, install backdoors, modify existing files, or establish persistent access to the compromised system. The vulnerability is particularly dangerous because it requires minimal prerequisites for exploitation - primarily only the ability to send HTTP requests to the vulnerable application. The risk is amplified when the target server has register_globals enabled, which was a common configuration in many php installations during the time this vulnerability was prevalent. Organizations running vulnerable versions of phpBB TopList face significant exposure to automated exploitation attempts, as this type of vulnerability is easily detectable by common web application scanners and attack frameworks.
Mitigation strategies for CVE-2006-2151 focus on immediate remediation and configuration hardening. The primary recommendation involves upgrading to a patched version of phpBB TopList, specifically versions 1.3.9 or later where the vulnerability has been addressed through proper input validation and sanitization of the phpbb_root_path parameter. Additionally, organizations should disable the register_globals directive in their php configuration files, as this setting fundamentally undermines web application security by creating automatic variable injection points. Network-level protections such as web application firewalls can provide additional layers of defense by monitoring for suspicious file inclusion patterns and blocking known malicious payloads. Security administrators should also implement proper input validation mechanisms that explicitly check and sanitize all user-supplied parameters before they are used in file operations. The vulnerability serves as a prime example of why proper secure coding practices are essential in web development, particularly regarding the handling of file paths and user input. Organizations should conduct comprehensive vulnerability assessments to identify other instances of similar flaws within their php applications and ensure that all web applications follow secure coding standards that prevent such dangerous parameter handling practices.