CVE-2024-51252
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands on Draytek Vigor3900 routers by injecting malicious commands into the mainfunction.cgi restore function. Attackers can gain full control of affected devices, potentially compromising entire networks. Organizations using Draytek Vigor3900 routers with the vulnerable firmware are affected.
💻 Affected Systems
- Draytek Vigor3900
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router leading to network takeover, data exfiltration, lateral movement to internal systems, and persistent backdoor installation.
Likely Case
Router compromise allowing network traffic interception, credential theft, and use as a pivot point for attacking internal systems.
If Mitigated
Limited impact if network segmentation isolates the router and strict access controls prevent exploitation attempts.
🎯 Exploit Status
The exploit requires sending crafted HTTP requests to the vulnerable endpoint, which is straightforward for attackers with network access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Unknown
Restart Required: Yes
Instructions:
1. Check Draytek's official website for security advisories
2. Download the latest firmware if available
3. Backup current configuration
4. Upload and install the new firmware via web interface
5. Restart the router
6. Restore configuration if needed
🔧 Temporary Workarounds
Network Access Restriction
allRestrict access to the router's management interface to trusted IP addresses only
Disable Unnecessary Services
allDisable remote management and any unnecessary CGI services if not required
🧯 If You Can't Patch
- Isolate the router in a dedicated network segment with strict firewall rules
- Implement network monitoring and intrusion detection for suspicious traffic to the router
🔍 How to Verify
Check if Vulnerable:
Check the firmware version in the router's web interface under System Maintenance > Firmware InformationCheck Version:
Not applicable - check via web interfaceVerify Fix Applied:
Verify the firmware version has been updated to a version later than 1.5.1.3📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to mainfunction.cgi
- Multiple failed restore attempts
- Unexpected system command execution in logs
Network Indicators:
- HTTP requests to /cgi-bin/mainfunction.cgi with command injection patterns
- Unusual outbound connections from the router
SIEM Query:
source="router_logs" AND (uri="/cgi-bin/mainfunction.cgi" AND method="POST" AND (content CONTAINS "restore" OR content CONTAINS "cmd" OR content CONTAINS "bash"))