CVE-2006-4893 in phpBB XS
Summary
by MITRE
PHP remote file inclusion vulnerability in bb_usage_stats/includes/bb_usage_stats.php in phpBB XS 0.58 and earlier allows remote attackers to execute arbitrary PHP code via a URL in the phpbb_root_path parameter, a different vector than CVE-2006-4780.
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Analysis
by VulDB Data Team • 08/08/2017
The vulnerability identified as CVE-2006-4893 represents a critical remote file inclusion flaw in the phpBB XS 0.58 and earlier versions, specifically within the bb_usage_stats.php file located in the bb_usage_stats/includes directory. This vulnerability operates through the phpbb_root_path parameter, which serves as an entry point for malicious actors to inject and execute arbitrary PHP code on vulnerable systems. The flaw stems from inadequate input validation and sanitization mechanisms that fail to properly filter user-supplied data before incorporating it into file inclusion operations. Unlike CVE-2006-4780 which targeted different vectors, this vulnerability specifically exploits the improper handling of the phpbb_root_path parameter, making it a distinct yet equally dangerous attack surface. The vulnerability aligns with CWE-98, which describes improper neutralization of special elements used in os command injection attacks, and more specifically with CWE-88, which addresses improper neutralization of argument separators in shell commands. From an operational perspective, this vulnerability enables attackers to execute malicious code remotely without requiring authentication or local access to the system, making it particularly attractive for automated exploitation campaigns.
The technical implementation of this vulnerability occurs when the application accepts user input through the phpbb_root_path parameter and directly incorporates it into a file inclusion function without proper validation or sanitization. Attackers can craft malicious URLs containing PHP code within the phpbb_root_path parameter, which gets executed when the application processes the inclusion request. This creates a pathway for attackers to upload and execute backdoors, steal sensitive data, or establish persistent access to compromised systems. The vulnerability's impact extends beyond simple code execution as it can facilitate privilege escalation, data exfiltration, and lateral movement within compromised networks. The attack vector leverages the trust placed in legitimate application functionality, making detection more challenging as malicious activity can appear to originate from legitimate application processes. This type of vulnerability is classified under the ATT&CK framework as T1059.007 - Command and Scripting Interpreter: PHP, and T1505.003 - Server Software Component: Web Shell, demonstrating how attackers can leverage such flaws to establish persistent access and maintain control over compromised systems.
Organizations affected by this vulnerability should implement immediate mitigations including updating to phpBB XS version 0.59 or later, which contains patches addressing this specific flaw. Additionally, administrators should apply input validation measures to restrict the phpbb_root_path parameter to only accept expected values and reject any suspicious input patterns. Network segmentation and firewall rules should be configured to limit access to vulnerable components, while web application firewalls can be deployed to detect and block malicious requests targeting this vulnerability. The implementation of proper parameter sanitization, input validation, and output encoding should be enforced throughout the application codebase to prevent similar issues from occurring in other components. Regular security audits and vulnerability assessments should be conducted to identify and remediate similar weaknesses in other applications and systems. The vulnerability demonstrates the critical importance of secure coding practices and input validation, as it could have been prevented through proper sanitization of user-supplied data before inclusion operations. Organizations should also implement monitoring and logging mechanisms to detect unusual file inclusion patterns that may indicate exploitation attempts, while maintaining up-to-date security patches and conducting regular vulnerability assessments to prevent similar issues from arising in the future.