CVE-2024-45887
📋 TL;DR
DrayTek Vigor3900 routers running firmware version 1.5.1.3 contain a post-authentication command injection vulnerability in the OpenVPN configuration handler. This allows authenticated attackers to execute arbitrary commands with root privileges on the device. Organizations using affected DrayTek routers are at risk.
💻 Affected Systems
- DrayTek Vigor3900
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to install persistent backdoors, pivot to internal networks, intercept all traffic, or brick the device.
Likely Case
Attacker gains full control of the router to modify network configurations, intercept traffic, or use as a foothold for lateral movement.
If Mitigated
Limited to authenticated users only, reducing attack surface to authorized personnel or compromised credentials.
🎯 Exploit Status
Exploit requires authentication but is straightforward once authenticated. Public proof-of-concept code exists.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Unknown
Restart Required: Yes
Instructions:
1. Check DrayTek website for security advisories
2. Download latest firmware if available
3. Backup current configuration
4. Upload and install new firmware
5. Restart device
6. Restore configuration if needed
🔧 Temporary Workarounds
Disable OpenVPN Web Interface
allRemove or restrict access to the vulnerable OpenVPN configuration interface
Network Segmentation
allIsolate Vigor3900 management interface from untrusted networks
🧯 If You Can't Patch
- Implement strict access controls to management interface (IP whitelisting, VPN-only access)
- Change all default credentials and enforce strong authentication policies
🔍 How to Verify
Check if Vulnerable:
Check if device is running firmware version 1.5.1.3 and has OpenVPN functionality enabledCheck Version:
Login to web interface and check System Status > Firmware InformationVerify Fix Applied:
Verify firmware version is updated beyond 1.5.1.3 and test OpenVPN configuration functionality📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /cgi-bin/mainfunction.cgi with action=doOpenVPN
- Unexpected command execution in system logs
Network Indicators:
- Suspicious traffic patterns from router management interface
- Unexpected outbound connections from router
SIEM Query:
source="vigor3900" AND (uri="/cgi-bin/mainfunction.cgi" AND params.action="doOpenVPN")