CVE-2024-51259
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands on DrayTek Vigor3900 routers by injecting malicious commands into the mainfunction.cgi endpoint. Attackers can achieve full system compromise without authentication. All organizations using affected DrayTek Vigor3900 routers are at risk.
💻 Affected Systems
- DrayTek Vigor3900
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover allowing attackers to install persistent backdoors, steal credentials, pivot to internal networks, and disrupt network operations.
Likely Case
Attackers gain remote code execution to deploy malware, create backdoors, intercept network traffic, and potentially ransom the device.
If Mitigated
If network segmentation and proper access controls are in place, impact may be limited to the router itself rather than the entire network.
🎯 Exploit Status
The GitHub reference contains technical details that could be used to create working exploits. The vulnerability requires no authentication and has simple command injection.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Unknown - Check DrayTek official website for security advisories
Restart Required: Yes
Instructions:
1. Check DrayTek website for firmware updates. 2. Download latest firmware. 3. Backup current configuration. 4. Upload and install new firmware via web interface. 5. Restart router. 6. Restore configuration if needed.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the web management interface if not required, reducing attack surface
Navigate to System Maintenance > Management > Web Management > Disable
Restrict Web Interface Access
allLimit web interface access to specific trusted IP addresses only
Navigate to System Maintenance > Management > Web Management > Set allowed IP addresses
🧯 If You Can't Patch
- Isolate the router in a separate VLAN with strict firewall rules limiting inbound/outbound traffic
- Implement network monitoring and intrusion detection specifically for command injection attempts to the web interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: System Maintenance > System Information > Firmware VersionCheck Version:
Check web interface at System Maintenance > System Information or use SNMP query if configuredVerify Fix Applied:
Verify firmware version is updated beyond 1.5.1.3 and test if command injection attempts are blocked📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to mainfunction.cgi
- Command injection patterns in web logs
- Multiple failed login attempts followed by successful command execution
Network Indicators:
- Unusual outbound connections from router
- Traffic patterns indicating command and control communication
- Unexpected port scans originating from router
SIEM Query:
source="router_logs" AND (uri="*mainfunction.cgi*" AND (cmd="*;*" OR cmd="*|*" OR cmd="*`*" OR cmd="*$(*"))