CVE-2024-51258
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands on DrayTek Vigor3900 routers by injecting malicious commands into the mainfunction.cgi script. Attackers can exploit this by calling the doSSLTunnel function, potentially gaining full control of affected devices. Organizations using DrayTek Vigor3900 routers with vulnerable firmware are affected.
💻 Affected Systems
- DrayTek Vigor3900
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router allowing attackers to intercept all network traffic, pivot to internal networks, install persistent backdoors, and use the device for further attacks.
Likely Case
Attackers gain shell access to execute commands, potentially stealing credentials, modifying network configurations, or using the router as a foothold for lateral movement.
If Mitigated
Limited impact if network segmentation isolates the router and strict access controls prevent external exploitation attempts.
🎯 Exploit Status
The GitHub reference contains technical details that could be used to develop exploits. Command injection vulnerabilities are typically easy to weaponize.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Unknown
Restart Required: Yes
Instructions:
1. Check DrayTek's official website for security advisories. 2. If a patch is available, download the firmware update. 3. Backup current configuration. 4. Upload and apply the new firmware. 5. Restart the router. 6. Verify the update was successful.
🔧 Temporary Workarounds
Disable CGI Script Access
allRestrict access to mainfunction.cgi if not required for functionality
Network Segmentation
allIsolate the router from critical internal networks
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach the router's management interface
- Monitor for unusual network traffic or configuration changes on the router
🔍 How to Verify
Check if Vulnerable:
Check the firmware version in the router's web interface under System Maintenance > Firmware InformationCheck Version:
No CLI command available; check via web interface at System Maintenance > Firmware InformationVerify Fix Applied:
Verify the firmware version has been updated to a version later than 1.5.1.3📡 Detection & Monitoring
Log Indicators:
- Unusual CGI script executions
- Unexpected command execution in system logs
- Failed authentication attempts followed by successful access
Network Indicators:
- Unusual outbound connections from the router
- Traffic patterns suggesting command and control activity
- Unexpected SSL/Tunnel connections
SIEM Query:
source="router_logs" AND ("mainfunction.cgi" OR "doSSLTunnel") AND (command="*" OR exec="*")