CVE-2006-6879 in PHP-Update
Summary
by MITRE
Unrestricted file upload vulnerability in admin/uploads.php in PHP-Update 2.7 and earlier allows remote authenticated users to upload arbitrary PHP scripts to the gfx/ and files/ directories via the userfile parameter.
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Analysis
by VulDB Data Team • 08/14/2024
The vulnerability identified as CVE-2006-6879 represents a critical security flaw in PHP-Update version 2.7 and earlier, specifically within the administrative upload functionality. This issue stems from inadequate input validation and access control mechanisms that permit authenticated users to bypass file type restrictions and upload malicious files to critical system directories. The vulnerability affects the admin/uploads.php component which handles file uploads for the web application, creating a pathway for attackers to execute arbitrary code on the target system. The flaw is particularly dangerous because it allows remote authenticated users to upload PHP scripts directly to the gfx/ and files/ directories, which are typically used for storing website media and documents respectively.
The technical exploitation of this vulnerability occurs through the userfile parameter in the upload functionality, which fails to properly validate file extensions or content types before processing uploads. This unrestricted file upload mechanism creates a direct code execution vector where attackers can upload malicious PHP scripts that will be executed by the web server when accessed. The vulnerability is classified as a CWE-434 Unrestricted Upload of File with Dangerous Type, which is a well-documented weakness in web application security that has been consistently identified in security assessments and penetration testing. The flaw essentially allows an authenticated user to escalate privileges and gain persistent access to the web server through the uploaded malicious files.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a persistent foothold in the target environment. Once a malicious PHP script is uploaded to the gfx/ or files/ directories, it can be executed by the web server, potentially allowing attackers to perform various malicious activities including data exfiltration, privilege escalation, and establishing backdoors for future access. The vulnerability is particularly concerning because it requires only authenticated access, meaning that any user with legitimate credentials to the PHP-Update system can exploit this flaw. This makes it a significant risk for organizations where user access controls are not properly enforced or where legitimate users might be compromised through social engineering or credential theft.
Security mitigation strategies for this vulnerability must address both the immediate code-level fix and broader access control improvements. The primary remediation involves implementing strict file type validation and content checking mechanisms that prevent the upload of executable scripts or files with dangerous extensions. Organizations should implement proper input sanitization and file validation routines that check file headers, MIME types, and extensions against a whitelist of allowed file types. Additionally, the upload directories should be configured with appropriate access controls to prevent direct execution of uploaded files, and the web server should be configured to treat uploaded files as static content rather than executable code. This vulnerability aligns with ATT&CK technique T1190 for Exploit Public-Facing Application and T1059 for Command and Scripting Interpreter, demonstrating how unrestricted file uploads can lead to broader compromise of web applications. Organizations should also implement regular security assessments and vulnerability scanning to identify similar issues in their web applications and ensure proper access controls are maintained throughout their systems.