CVE-2004-2018 in PHP-Nuke
Summary
by MITRE
PHP remote file inclusion vulnerability in index.php in Php-Nuke 6.x through 7.3 allows remote attackers to execute arbitrary PHP code by modifying the modpath parameter to reference a URL on a remote web server that contains the code.
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Analysis
by VulDB Data Team • 05/06/2025
The vulnerability described in CVE-2004-2018 represents a critical remote file inclusion flaw affecting PHP-Nuke versions 6.x through 7.3. This issue resides in the index.php file and demonstrates a classic path traversal vulnerability that enables attackers to inject malicious code from remote servers. The flaw operates by manipulating the modpath parameter, which is processed without adequate input validation or sanitization, allowing threat actors to reference external URLs containing malicious PHP code. This vulnerability directly aligns with CWE-98, which categorizes improper input validation leading to remote file inclusion attacks. The attack vector leverages the trust model inherent in PHP applications where legitimate modules are expected to be included from local paths, but the application fails to distinguish between authorized local paths and unauthorized remote references.
The technical implementation of this vulnerability exploits the fundamental design assumption that module paths are controlled and secure within the application's local filesystem. When attackers modify the modpath parameter to include a remote URL, the PHP application processes this input by including the referenced file directly into the execution context. This process bypasses normal security controls and allows arbitrary code execution on the target server. The vulnerability's severity is amplified by the fact that it affects multiple versions of PHP-Nuke, indicating a persistent flaw in the application's architecture that was not properly addressed across the product lifecycle. According to ATT&CK framework, this vulnerability maps to T1190 - Exploit Public-Facing Application, where attackers leverage application weaknesses to execute malicious code remotely.
The operational impact of CVE-2004-2018 extends far beyond simple code execution, as successful exploitation can lead to complete system compromise. Attackers can upload backdoors, steal sensitive data, modify content, or establish persistent access through the compromised web server. The vulnerability creates a persistent threat vector that can be exploited repeatedly without requiring additional authentication or privileges. Organizations running affected PHP-Nuke versions face significant risk of data breaches, service disruption, and potential regulatory compliance violations. The remote nature of the attack means that exploitation can occur from anywhere on the internet, making defense-in-depth strategies crucial. This vulnerability also demonstrates the importance of input validation and the principle of least privilege in web application security design.
Mitigation strategies for CVE-2004-2018 require immediate implementation of multiple defensive measures. The most effective approach involves disabling remote file inclusion features in PHP applications by setting allow_url_fopen and allow_url_include directives to false in php.ini configuration files. Additionally, strict input validation must be implemented to ensure that all modpath parameters are validated against a whitelist of known safe local paths. Application-level restrictions should prevent any user-controllable input from being directly used in include or require statements. Organizations should also implement proper network segmentation and web application firewalls to detect and block suspicious requests targeting the vulnerable parameter. Regular security updates and patches should be applied immediately upon availability, as this vulnerability was addressed in later versions of PHP-Nuke. The remediation process must include comprehensive security testing to verify that no other similar vulnerabilities exist within the application's codebase, as this flaw represents a broader pattern of insecure coding practices that may affect other parameters or functions within the application.