CVE-2020-7246: Qdpm RCE Vulnerability via File Upload

CVE-2020-7246 Overview

A remote code execution (RCE) vulnerability exists in qdPM 9.1 and earlier versions. The vulnerability allows an authenticated attacker to upload a malicious PHP code file via the profile photo functionality by exploiting a path traversal vulnerability in the users['photop_preview'] delete photo feature. This flaw enables attackers to bypass .htaccess protection mechanisms, ultimately achieving arbitrary code execution on the target server. This vulnerability exists due to an incomplete fix for CVE-2015-3884.

Critical Impact

Authenticated attackers can achieve remote code execution by uploading malicious PHP files, bypassing server-side protections through path traversal techniques.

Affected Products

• qdPM 9.1 and earlier versions

Discovery Timeline

• 2020-01-21 - CVE-2020-7246 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-7246

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), commonly known as a Path Traversal vulnerability. The flaw resides in the profile photo upload and deletion functionality within qdPM's user management system. The attack requires network access and low-privilege authentication, but once these conditions are met, an attacker can fully compromise the confidentiality, integrity, and availability of the target system.

The vulnerability stems from an incomplete remediation of the earlier CVE-2015-3884, indicating that the initial patch failed to adequately address all attack vectors related to file upload handling and path validation.

Root Cause

The root cause of this vulnerability lies in improper input validation within the users['photop_preview'] parameter during the photo deletion process. The application fails to properly sanitize user-supplied input containing path traversal sequences (such as ../), allowing attackers to manipulate file paths and write malicious PHP files outside the intended upload directory. This bypass circumvents .htaccess restrictions that would normally prevent execution of uploaded files.

Attack Vector

The attack is executed over the network and requires the attacker to have low-level authenticated access to the qdPM application. The exploitation flow involves:

1. An authenticated user accesses the profile photo upload functionality
2. The attacker crafts a malicious PHP file (webshell or reverse shell)
3. By manipulating the users['photop_preview'] parameter with path traversal sequences, the attacker can place the malicious file in an executable location
4. The path traversal bypasses .htaccess protections that would otherwise block PHP execution in upload directories
5. The attacker then accesses the uploaded PHP file directly, achieving remote code execution

Technical details and proof-of-concept exploits are available in the Packet Storm Security Advisory and additional exploit documentation.

Detection Methods for CVE-2020-7246

Indicators of Compromise

• Unexpected PHP files appearing in web-accessible directories outside the designated uploads folder
• Web server access logs showing requests to unfamiliar PHP files with shell-like functionality
• HTTP POST requests to profile photo upload endpoints containing path traversal sequences (../)
• Presence of webshell artifacts such as eval(), system(), exec(), or passthru() in newly created PHP files

Detection Strategies

• Monitor web application logs for requests to the user profile photo functionality containing suspicious path patterns
• Implement file integrity monitoring on the qdPM web root to detect unauthorized file creation
• Deploy web application firewall (WAF) rules to detect and block path traversal attempts in POST parameters
• Review HTTP request logs for anomalous file upload activity, particularly requests with encoded traversal sequences

Monitoring Recommendations

• Enable detailed logging on the web server for all file upload operations
• Configure alerts for any new PHP file creation outside designated upload directories
• Monitor for outbound connections from the web server that may indicate reverse shell activity
• Implement behavioral analysis to detect post-exploitation activity following successful RCE

How to Mitigate CVE-2020-7246

Immediate Actions Required

• Upgrade qdPM to a version newer than 9.1 that addresses this vulnerability
• Restrict access to the qdPM application to trusted users only until patching is complete
• Implement additional input validation and path sanitization at the web application firewall level
• Review the web server for any signs of compromise or unauthorized PHP files

Patch Information

Organizations should upgrade to the latest version of qdPM that contains a complete fix for this path traversal vulnerability. No official vendor advisory URL was provided in the CVE data. For technical details on the vulnerability, refer to the Google Doc Security Review and Packet Storm advisories.

Workarounds

• Disable the profile photo upload functionality if not required for business operations
• Implement strict file type validation at both the application and web server levels
• Configure web server to prevent PHP execution in upload directories using server-level configurations rather than relying solely on .htaccess
• Deploy a reverse proxy or WAF to filter requests containing path traversal patterns

# Apache configuration to prevent PHP execution in uploads directory
<Directory "/var/www/html/qdpm/uploads">
    php_admin_flag engine off
    RemoveHandler .php .phtml .php3 .php4 .php5 .phps
    AddType text/plain .php .phtml .php3 .php4 .php5 .phps
</Directory>