CVE-2024-51255
📋 TL;DR
CVE-2024-51255 is a command injection vulnerability in DrayTek Vigor3900 routers that allows attackers to execute arbitrary commands via the mainfunction.cgi script. Attackers can exploit this by injecting malicious commands into the ruequest_certificate function. This affects organizations using vulnerable DrayTek Vigor3900 routers.
💻 Affected Systems
- DrayTek Vigor3900
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router with full administrative control, enabling network traffic interception, lateral movement to internal systems, and persistent backdoor installation.
Likely Case
Router takeover leading to network disruption, credential theft, and deployment of malware to connected devices.
If Mitigated
Limited impact with proper network segmentation and firewall rules preventing external access to management interfaces.
🎯 Exploit Status
The GitHub reference contains technical details and likely exploit code. The high CVSS score and command injection nature make weaponization straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Unknown - Check DrayTek security advisories
Restart Required: Yes
Instructions:
1. Check DrayTek website for firmware updates
2. Download latest firmware for Vigor3900
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 vulnerable web interface to prevent exploitation
Access router CLI via SSH/Telnet
Navigate to system settings
Disable HTTP/HTTPS management services
Restrict Management Access
allLimit access to management interface to trusted IPs only
Configure firewall rules to allow management access only from specific IP ranges
Disable WAN access to management interface
🧯 If You Can't Patch
- Isolate vulnerable routers in separate network segments with strict firewall rules
- Implement network monitoring and IDS/IPS to detect exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: System Maintenance > System Status > Firmware VersionCheck Version:
ssh admin@router-ip 'show version' or check web interfaceVerify Fix Applied:
Verify firmware version is updated beyond 1.5.1.3 and test ruequest_certificate function with safe payloads📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in system logs
- Multiple failed login attempts followed by successful access
- Suspicious CGI requests to mainfunction.cgi
Network Indicators:
- Unusual outbound connections from router
- Traffic patterns indicating command and control activity
- HTTP requests with command injection patterns to ruequest_certificate
SIEM Query:
source="router_logs" AND (uri="*mainfunction.cgi*" AND (param="*ruequest_certificate*" OR cmd="*;*" OR cmd="*|*" OR cmd="*`*"))