CVE-2008-6207 in PHPG Upload
Summary
by MITRE
Unrestricted file upload vulnerability in form_upload.php in PHPG Upload 1.0 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. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.
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Analysis
by VulDB Data Team • 11/26/2017
The vulnerability described in CVE-2008-6207 represents a critical unrestricted file upload flaw in PHPG Upload version 1.0 that enables authenticated remote attackers to achieve arbitrary code execution. This vulnerability exists within the form_upload.php component of the software, which fails to properly validate or restrict file extensions during the upload process. The flaw allows attackers who have gained authentication credentials to upload malicious files with executable extensions such as .php, .asp, or .jsp, thereby compromising the affected system. The vulnerability is particularly dangerous because it does not require special privileges beyond authentication, making it accessible to users who can establish valid login sessions with the application. The security implications extend beyond simple file upload functionality, as this flaw can be leveraged to establish persistent backdoors, execute malicious scripts, or gain full control over the web server hosting the vulnerable application.
The technical exploitation of this vulnerability follows a straightforward but devastating pattern. Once authenticated, an attacker can upload a specially crafted file containing malicious code with an extension that the application accepts as valid for execution. The vulnerability stems from inadequate input validation and sanitization processes within the file upload mechanism, which should have implemented strict whitelisting of allowed file extensions and performed comprehensive content inspection. This flaw aligns with CWE-434, which specifically addresses the issue of unrestricted file upload, where the system allows users to upload files without proper validation of file type, content, or extension. The vulnerability's severity is amplified by the fact that the uploaded files can be directly accessed through HTTP requests, eliminating the need for additional attack vectors or complex exploitation techniques. The attack chain typically involves uploading a web shell or malicious script, then accessing it through a direct URL request to execute commands on the target system.
The operational impact of CVE-2008-6207 extends far beyond simple data compromise, potentially enabling complete system takeover and persistent access for attackers. Organizations running vulnerable versions of PHPG Upload face significant risks including data exfiltration, system infiltration, and establishment of command and control channels. The vulnerability can be exploited to deploy web shells that provide attackers with ongoing access to the compromised server, allowing them to perform reconnaissance, escalate privileges, and maintain persistence. This type of vulnerability also creates opportunities for attackers to use the compromised system as a launching point for further attacks against internal networks, potentially leading to lateral movement and broader security breaches. The vulnerability's impact is particularly concerning in environments where the application is hosted on publicly accessible servers or where the authenticated users have broad permissions, as it can be exploited by both internal and external threat actors. The potential for denial of service attacks also exists if attackers upload large files or files designed to consume system resources.
Mitigation strategies for CVE-2008-6207 must address both the immediate vulnerability and broader security practices within the application architecture. Organizations should implement strict file type validation by maintaining a whitelist of allowed extensions and rejecting all others, while also performing content-based checks to ensure uploaded files match their claimed extensions. The application should store uploaded files outside the web root directory and ensure proper file permissions are enforced to prevent direct execution of uploaded content. Additionally, implementing multiple layers of security including input sanitization, file content verification, and regular security audits can significantly reduce the risk of exploitation. The remediation process should include immediate patching or upgrading to a secure version of PHPG Upload, as well as implementing proper access controls and monitoring for suspicious upload activities. Organizations should also consider implementing web application firewalls and intrusion detection systems to identify and block attempts to exploit this vulnerability, while following ATT&CK framework techniques for detecting and preventing file upload attacks through T1190 (Exploit Public-Facing Application) and T1059 (Command and Scripting Interpreter) tactics. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other applications and components within the organization's infrastructure.