CVE-2006-5301 in SpamBlockerMOD
Summary
by MITRE
PHP remote file inclusion vulnerability in includes/antispam.php in the SpamBlockerMODv 1.0.2 and earlier module for phpBB allows remote attackers to execute arbitrary PHP code via a URL in the phpbb_root_path parameter.
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Analysis
by VulDB Data Team • 04/24/2026
The vulnerability identified as CVE-2006-5301 represents a critical remote file inclusion flaw within the SpamBlockerMOD phpBB module version 1.0.2 and earlier. This vulnerability exists in the antispam.php file which is part of a widely used spam protection module for the phpBB bulletin board system. The flaw allows remote attackers to inject malicious URLs into the phpbb_root_path parameter, thereby enabling arbitrary code execution on the affected server. The vulnerability specifically affects the module's improper handling of user-supplied input without adequate sanitization or validation, creating an exploitable path for malicious actors to execute unauthorized PHP code.
From a technical perspective, this vulnerability constitutes a classic remote file inclusion (RFI) attack vector that operates through parameter manipulation. The antispam.php script fails to properly validate or sanitize the phpbb_root_path parameter, which is directly used in file inclusion operations. When an attacker supplies a malicious URL as the value for this parameter, the application attempts to include and execute the remote file, effectively allowing the attacker to inject and execute arbitrary PHP code on the target system. This type of vulnerability is categorized under CWE-88 as "Improper Neutralization of Argument Delimiters in a Command" and more specifically relates to CWE-94 as "Improper Control of Generation of Code ('Code Injection')."
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with complete control over the affected phpBB installation. Successful exploitation can result in full system compromise, data theft, defacement, or the installation of backdoors for persistent access. Attackers can leverage this vulnerability to execute commands with the privileges of the web server process, potentially leading to further network infiltration. The vulnerability affects not only the immediate phpBB installation but can also serve as a stepping stone for attacking other systems within the same network infrastructure. According to ATT&CK framework, this vulnerability maps to T1190 "Exploit Public-Facing Application" and T1059.007 "Command and Scripting Interpreter: PHP," demonstrating the attack chain from initial access through code execution.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements. The primary solution involves upgrading to a patched version of the SpamBlockerMOD module where the phpbb_root_path parameter is properly validated and sanitized. Organizations should implement input validation measures that prevent URL inclusion in critical parameters and ensure that all user-supplied input undergoes proper sanitization before being processed. Additionally, the principle of least privilege should be enforced by configuring the web server to restrict file inclusion operations to local paths only. Security measures such as disabling remote file inclusion in php.ini configuration, implementing web application firewalls, and conducting regular security audits can provide additional layers of protection. The vulnerability also underscores the importance of keeping all third-party modules and applications updated, as this flaw was present in versions up to 1.0.2 and likely affected many installations that had not been properly maintained.