CVE-2006-2735 in Activity MOD Plus
Summary
by MITRE
PHP remote file inclusion vulnerability in language/lang_english/lang_activity.php in Activity MOD Plus (Amod) 1.1.0, as used with phpBB when register_globals is enabled, allows remote attackers to execute arbitrary PHP code via a URL in the phpbb_root_path parameter. NOTE: This is a similar vulnerability to CVE-2006-2507.
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Analysis
by VulDB Data Team • 06/22/2025
The vulnerability described in CVE-2006-2735 represents a critical remote file inclusion flaw affecting the Activity MOD Plus (Amod) 1.1.0 component when integrated with phpBB platforms. This vulnerability specifically targets the language file lang_english/lang_activity.php which fails to properly validate input parameters, creating an exploitable condition that can be leveraged by remote attackers to execute arbitrary PHP code on vulnerable systems. The flaw occurs when the register_globals configuration directive is enabled in the phpBB environment, which effectively transforms superglobal variables into regular variables accessible throughout the application scope.
The technical exploitation mechanism relies on the insecure handling of the phpbb_root_path parameter within the affected language file. When register_globals is enabled, user-supplied input passed through this parameter can be directly interpreted as a PHP file path, allowing attackers to inject malicious URLs that get included and executed by the PHP interpreter. This creates a classic remote code execution scenario where attackers can upload and execute malicious scripts, potentially gaining full control over the affected web server. The vulnerability demonstrates a clear violation of input validation principles and represents a direct consequence of improper parameter sanitization within the application's include mechanism.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with the capability to perform comprehensive system compromise operations. Once executed, the malicious code can be used to establish backdoors, exfiltrate sensitive data, modify database contents, or even escalate privileges within the compromised environment. The vulnerability affects not just individual applications but entire phpBB installations that have not properly configured their register_globals settings, making it particularly dangerous in shared hosting environments where multiple applications may be running. This flaw directly relates to CWE-94, which describes the weakness of allowing arbitrary code execution through insecure use of dynamic code generation or execution, and aligns with ATT&CK technique T1059.007 for execution through PHP.
Security mitigations for this vulnerability require immediate implementation of multiple defensive measures to protect affected systems. The primary recommendation involves disabling the register_globals directive in php.ini configuration files, as this setting fundamentally enables the attack vector by making user input directly available as variables. Additionally, developers should implement strict input validation and sanitization for all parameters passed to include or require functions, ensuring that only predetermined safe paths are accepted. The affected Amod component should be updated to version 1.1.1 or later, which contains patches addressing this specific vulnerability. Organizations should also implement proper access controls and network segmentation to limit exposure, while monitoring for suspicious file inclusion patterns in web server logs. The vulnerability serves as a critical reminder of the importance of secure coding practices and proper input validation, particularly when dealing with dynamic file inclusion operations that can be manipulated by untrusted input sources.