CVE-2024-31777: Openeclass File Upload RCE Vulnerability

CVE-2024-31777 Overview

CVE-2024-31777 is a critical file upload vulnerability affecting Open eClass, a popular open-source e-learning platform. The vulnerability allows an unauthenticated attacker to execute arbitrary code on the server by uploading a crafted malicious file to the certbadge.php endpoint. This type of unrestricted file upload flaw (CWE-434) represents one of the most dangerous web application vulnerabilities, as it can lead to complete server compromise.

Critical Impact

Unauthenticated remote code execution through unrestricted file upload allows attackers to fully compromise Open eClass servers, potentially exposing sensitive student and institutional data.

Affected Products

• Open eClass version 3.15 and all earlier versions
• Educational institutions and organizations running vulnerable Open eClass deployments
• Self-hosted Open eClass installations without proper file upload restrictions

Discovery Timeline

• 2024-06-13 - CVE-2024-31777 published to NVD
• 2025-06-18 - Last updated in NVD database

Technical Details for CVE-2024-31777

Vulnerability Analysis

This vulnerability stems from improper validation of uploaded files in the certbadge.php endpoint within Open eClass. The application fails to adequately verify the type, content, and extension of uploaded files, allowing attackers to bypass security controls and upload executable scripts. When a malicious file such as a PHP web shell is uploaded and subsequently accessed, the web server executes the code with the privileges of the web application, granting the attacker remote code execution capabilities.

The vulnerability is particularly severe because it requires no authentication—any network-connected attacker can exploit this flaw without needing valid credentials. Successful exploitation can result in complete confidentiality, integrity, and availability impact on the affected system.

Root Cause

The root cause of CVE-2024-31777 is a classic unrestricted file upload vulnerability (CWE-434). The certbadge.php endpoint lacks proper server-side validation mechanisms to:

1. Verify that uploaded files match expected file types (e.g., image files for certificates/badges)
2. Check file content signatures (magic bytes) rather than relying solely on file extensions
3. Prevent execution of uploaded files by the web server
4. Sanitize or reject potentially dangerous file extensions such as .php, .phtml, or .php5

Attack Vector

The attack is network-based and can be executed remotely without authentication. An attacker crafts a malicious file—typically a PHP web shell or reverse shell script—and uploads it through the vulnerable certbadge.php endpoint. The attacker may bypass weak client-side or extension-based validation by:

• Manipulating the Content-Type header in the HTTP request
• Using double extensions (e.g., malicious.php.jpg)
• Exploiting null byte injection in older PHP versions
• Embedding PHP code within valid image file structures

Once uploaded, the attacker accesses the malicious file's URL directly, triggering server-side code execution. A proof-of-concept exploit is available in the GitHub PoC Repository, demonstrating the exploitation technique.

Detection Methods for CVE-2024-31777

Indicators of Compromise

• Unexpected PHP files or web shells appearing in upload directories, particularly those associated with certificate or badge functionality
• HTTP POST requests to certbadge.php with unusual file types or suspicious filenames
• Web server access logs showing requests to newly uploaded files with executable extensions in upload paths
• Anomalous outbound connections from the web server process indicating reverse shell activity

Detection Strategies

• Monitor web application logs for POST requests to certbadge.php containing file uploads with executable extensions
• Implement file integrity monitoring on web-accessible directories to detect unauthorized file creation
• Deploy web application firewall (WAF) rules to block uploads with dangerous file extensions or content types
• Use intrusion detection systems to identify patterns consistent with web shell deployment and command execution

Monitoring Recommendations

• Enable detailed logging on the Open eClass application and web server, focusing on file upload activities
• Regularly scan upload directories for files with executable permissions or suspicious content signatures
• Configure alerts for any new executable files created in web-accessible directories
• Monitor for unusual process spawning from web server processes (e.g., www-data or apache user executing shell commands)

How to Mitigate CVE-2024-31777

Immediate Actions Required

• Upgrade Open eClass to a patched version beyond 3.15 that addresses the file upload vulnerability
• Restrict network access to the certbadge.php endpoint until patching is complete
• Audit existing upload directories for any previously uploaded malicious files and remove them
• Implement web application firewall rules to block suspicious file upload attempts

Patch Information

Organizations should update Open eClass to the latest available version that addresses this vulnerability. Review the official Open eClass project repository for security updates and patches. The GitHub PoC Repository provides additional technical context that can assist in understanding the vulnerability scope.

Workarounds

• Disable or restrict access to the certbadge.php endpoint if certificate/badge functionality is not required
• Implement strict file type validation at the web server level using .htaccess or server configuration to prevent PHP execution in upload directories
• Store uploaded files outside the web root or in directories configured to deny script execution
• Apply principle of least privilege to web server processes to limit damage from potential exploitation

# Apache configuration to prevent PHP execution in upload directories
<Directory "/var/www/openeclass/uploads">
    php_admin_flag engine off
    <FilesMatch "\.(php|phtml|php3|php4|php5|php7|phps)$">
        Require all denied
    </FilesMatch>
</Directory>