CVE-2008-6900 in Article Script
Summary
by MITRE
Unrestricted file upload vulnerability in "Add Pen/Author Name" feature in addpen.php in AvailScript Article Script allows remote authenticated users to execute arbitrary code by uploading a file with an executable extension, then accessing it via a direct request to the file in photos/.
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Analysis
by VulDB Data Team • 11/18/2024
The vulnerability described in CVE-2008-6900 represents a critical security flaw within the AvailScript Article Script platform that enables authenticated attackers to bypass file upload restrictions and execute arbitrary code on the target system. This vulnerability specifically targets the "Add Pen/Author Name" functionality in the addpen.php script, which serves as a legitimate feature for users to associate author information with articles. However, the implementation lacks proper validation mechanisms for uploaded files, creating a pathway for malicious actors to exploit the system's trust in user inputs.
The technical flaw stems from insufficient input validation and sanitization within the file upload process. When authenticated users upload files through the addpen.php script, the application fails to properly verify file extensions or content types before storing them in the photos/ directory. This oversight allows attackers to upload files with executable extensions such as .php, .asp, or .jsp, which can then be executed directly by the web server when accessed through a browser. The vulnerability is particularly dangerous because it leverages legitimate user authentication, making the attack appear as normal user activity rather than suspicious administrative behavior.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with persistent access to the compromised system. Once an attacker successfully uploads a malicious file, they can maintain control over the web server, potentially using the uploaded file as a backdoor for continued access or as a staging area for further attacks. The attacker can also leverage this capability to escalate privileges, access sensitive data, or deploy additional malware within the network. The direct request mechanism ensures that even if the initial upload is not immediately exploited, the malicious file remains accessible and executable for extended periods, creating a persistent threat vector.
Security professionals should address this vulnerability by implementing strict file type validation and sanitization measures within the AvailScript Article Script platform. The recommended approach includes implementing a whitelist-based file extension validation system that only accepts predetermined safe file types such as images, and rejecting any files with executable extensions. Additionally, uploaded files should be stored outside the web root directory or have their execution permissions disabled to prevent direct access. Organizations should also implement proper access controls and monitoring to detect unauthorized file uploads, as well as regular security audits to identify similar vulnerabilities in other applications. This vulnerability aligns with CWE-434, which specifically addresses "Unrestricted Upload of File with Dangerous Type," and represents a common pattern that appears in many web applications where proper input validation is missing from file upload mechanisms. The attack vector described in this CVE also maps to ATT&CK technique T1505.003, which involves the use of web shells for maintaining access to compromised systems.