CVE-2024-52677: Hkcms File Upload Vulnerability

CVE-2024-52677 Overview

CVE-2024-52677 is a critical unrestricted file upload vulnerability affecting HkCms versions 2.3.2.240702 and earlier. The vulnerability exists in the getFileName method within /app/common/library/Upload.php, allowing attackers to upload malicious files to the server without proper validation or restrictions.

Critical Impact

This vulnerability enables unauthenticated remote attackers to upload arbitrary files, potentially leading to remote code execution, complete server compromise, and unauthorized access to sensitive data.

Affected Products

• HkCms versions up to and including v2.3.2.240702
• All HkCms installations using the vulnerable Upload.php library component

Discovery Timeline

• 2024-11-20 - CVE-2024-52677 published to NVD
• 2025-03-13 - Last updated in NVD database

Technical Details for CVE-2024-52677

Vulnerability Analysis

This vulnerability falls under CWE-434 (Unrestricted Upload of File with Dangerous Type). The getFileName method in HkCms's upload functionality fails to properly validate and restrict file types during the upload process. This allows attackers to bypass security controls and upload files with executable extensions such as PHP scripts.

The network-accessible attack vector requires no authentication or user interaction, making this vulnerability particularly dangerous for internet-facing HkCms installations. Successful exploitation can lead to complete compromise of confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause lies in insufficient file validation within the getFileName method located at /app/common/library/Upload.php. The method does not properly sanitize or validate uploaded file extensions, allowing dangerous file types to be uploaded to the server. This inadequate input validation enables attackers to circumvent intended security restrictions.

Attack Vector

The attack vector is network-based, allowing remote exploitation without authentication. An attacker can craft a malicious HTTP request to the file upload endpoint, submitting a file with a dangerous extension (such as .php) that bypasses the insufficient validation in the getFileName method.

Once uploaded, the attacker can access the malicious file directly on the web server, triggering code execution. This typically involves:

1. Identifying the file upload endpoint in HkCms
2. Crafting a request with a malicious PHP webshell or backdoor
3. Uploading the file using the vulnerable getFileName method
4. Accessing the uploaded file via the web server to execute arbitrary commands

For detailed technical information and proof-of-concept documentation, refer to the GitHub PoC Repository and the GitHub Security Advisory.

Detection Methods for CVE-2024-52677

Indicators of Compromise

• Unexpected PHP files or other executable scripts appearing in upload directories
• Web server logs showing requests to newly created files in upload locations
• Suspicious POST requests to file upload endpoints with unusual file extensions
• Process execution anomalies originating from web server processes

Detection Strategies

• Monitor file system changes in HkCms upload directories for executable file types
• Implement web application firewall (WAF) rules to detect and block file upload attempts with dangerous extensions
• Review web server access logs for patterns indicating webshell access or command execution attempts
• Deploy endpoint detection solutions to identify post-exploitation behavior such as reverse shells or unauthorized process spawning

Monitoring Recommendations

• Enable verbose logging for file upload operations in HkCms
• Configure alerts for new file creation events in web-accessible directories
• Implement file integrity monitoring on the /app/common/library/ directory and upload locations
• Monitor outbound network connections from the web server for potential command-and-control traffic

How to Mitigate CVE-2024-52677

Immediate Actions Required

• Upgrade HkCms to a patched version that addresses the file upload vulnerability
• Implement strict file type validation at the application level, including extension whitelisting and MIME type verification
• Restrict file upload functionality to authenticated users only where possible
• Review and remove any suspicious files in upload directories

Patch Information

Organizations should check for updated releases from the HkCms project that address this vulnerability. Review the GitHub Security Advisory for official guidance on remediation.

Workarounds

• Implement server-side validation to restrict uploaded file extensions to a whitelist of safe types
• Configure the web server to prevent execution of scripts in upload directories
• Use a Web Application Firewall (WAF) to filter malicious upload requests
• Consider disabling file upload functionality if not essential to business operations

# Apache configuration to prevent PHP execution in upload directory
<Directory "/path/to/hkcms/uploads">
    php_flag engine off
    AddHandler default-handler .php .phtml .php3 .php4 .php5
    Options -ExecCGI
</Directory>