CVE-2024-46580
📋 TL;DR
A buffer overflow vulnerability in the Draytek Vigor 3910 router's v2x00.cgi component allows attackers to cause Denial of Service (DoS) by sending specially crafted input to the fid parameter. This affects organizations using Draytek Vigor 3910 routers with vulnerable firmware versions. The vulnerability can disrupt network services and potentially lead to system instability.
💻 Affected Systems
- Draytek Vigor 3910
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system crash requiring physical reboot, extended network downtime, and potential for remote code execution if the overflow can be controlled precisely.
Likely Case
Router becomes unresponsive, requiring manual reboot to restore functionality, causing temporary network disruption.
If Mitigated
Limited impact with proper network segmentation and monitoring, allowing quick detection and recovery.
🎯 Exploit Status
Buffer overflow vulnerabilities in CGI components are often straightforward to exploit for DoS, though achieving RCE would require more sophisticated exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Draytek's official website for firmware updates. 2. Download the latest firmware for Vigor 3910. 3. Access router admin interface. 4. Navigate to System Maintenance > Firmware Upgrade. 5. Upload and apply the new firmware. 6. Reboot the router.
🔧 Temporary Workarounds
Restrict Access to Web Interface
allLimit access to the router's web management interface to trusted IP addresses only.
Configure firewall rules to allow only specific source IPs to access router management ports (typically 80, 443, 8080)
Disable Unnecessary Services
allDisable remote management if not required.
In router admin: System Maintenance > Management > Disable 'Allow management from WAN'
🧯 If You Can't Patch
- Implement strict network segmentation to isolate the router from untrusted networks
- Deploy network-based intrusion prevention systems (IPS) to detect and block exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under System Maintenance > Firmware InformationCheck Version:
Login to router web interface and navigate to System Maintenance > Firmware InformationVerify Fix Applied:
Verify firmware version has been updated to a version newer than v4.3.2.6📡 Detection & Monitoring
Log Indicators:
- Multiple failed HTTP requests to v2x00.cgi with unusual fid parameter values
- Router system logs showing crashes or reboots
Network Indicators:
- Unusual HTTP traffic patterns to router management interface
- Large or malformed HTTP requests targeting v2x00.cgi
SIEM Query:
source="router_logs" AND (uri="*v2x00.cgi*" AND (fid="*[long_string]*" OR fid="*[special_chars]*"))