CVE-2020-19303
📋 TL;DR
This vulnerability allows attackers to upload arbitrary files to hdcms 5.7 via the /fileupload.php endpoint, potentially leading to remote code execution. Any system running the vulnerable version of hdcms is affected. Attackers can upload malicious files that get executed on the server.
💻 Affected Systems
- hdcms
📦 What is this software?
Hdcms by Houdunren
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the web server, data exfiltration, and lateral movement within the network.
Likely Case
Webshell deployment leading to data theft, defacement, or use as a foothold for further attacks.
If Mitigated
File uploads blocked or properly validated, preventing malicious file execution.
🎯 Exploit Status
The vulnerability is simple to exploit with publicly available proof-of-concept code. Attackers can upload files without authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Later versions after 5.7
Vendor Advisory: https://github.com/houdunwang/hdcms/issues/6
Restart Required: No
Instructions:
1. Upgrade hdcms to the latest version. 2. Replace the vulnerable /fileupload.php file with the patched version. 3. Verify file upload functionality still works correctly.
🔧 Temporary Workarounds
Disable file upload endpoint
linuxTemporarily disable or restrict access to the vulnerable /fileupload.php endpoint
mv /path/to/hdcms/fileupload.php /path/to/hdcms/fileupload.php.disabled
chmod 000 /path/to/hdcms/fileupload.php
Implement file upload restrictions
allAdd server-side validation to restrict file types and extensions
🧯 If You Can't Patch
- Implement strict file upload validation (whitelist allowed extensions, validate file content)
- Place file upload directory outside web root with proper permissions
🔍 How to Verify
Check if Vulnerable:
Check if hdcms version is 5.7 and if /fileupload.php exists without proper file validationCheck Version:
Check hdcms configuration files or admin panel for version informationVerify Fix Applied:
Test file upload functionality with malicious files to ensure they are rejected📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads to /fileupload.php
- Uploads of executable files (php, jsp, asp)
- Large number of failed upload attempts
Network Indicators:
- POST requests to /fileupload.php with suspicious file content
- Traffic patterns indicating webshell communication
SIEM Query:
source="web_logs" AND uri="/fileupload.php" AND (file_extension="php" OR file_extension="jsp" OR file_extension="asp")