CVE-2024-46558
📋 TL;DR
A buffer overflow vulnerability in Draytek Vigor 3910 routers allows attackers to cause Denial of Service (DoS) by sending crafted input to the newProname parameter in v2x00.cgi. This affects organizations using Draytek Vigor 3910 routers with vulnerable firmware versions. The vulnerability can disrupt network services and potentially lead to device instability.
💻 Affected Systems
- Draytek Vigor 3910
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device crash requiring physical reboot, extended network downtime, and potential for remote code execution if the overflow can be controlled to execute arbitrary code.
Likely Case
Service disruption causing temporary network outages, requiring device reboot to restore functionality.
If Mitigated
Minimal impact with proper network segmentation and access controls limiting exposure to the vulnerable endpoint.
🎯 Exploit Status
The vulnerability appears to be in a CGI endpoint that may be accessible without authentication. Buffer overflow exploitation typically requires some technical skill but is well-documented.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Draytek website for firmware updates
2. Download latest firmware for Vigor 3910
3. Access router web interface
4. Navigate to System Maintenance > Firmware Upgrade
5. Upload and apply new firmware
6. Reboot router after upgrade
🔧 Temporary Workarounds
Restrict Access to Management Interface
allLimit access to the router's web management interface to trusted IP addresses only
Configure firewall rules to restrict access to port 80/443 on the router to specific management IPs
Disable Remote Management
allTurn off remote management features if not required
In router web interface: 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 intrusion detection/prevention systems to monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface: System Maintenance > Firmware InformationCheck Version:
Not applicable - check via web interface or SSH if enabledVerify Fix Applied:
Verify firmware version is newer than v4.3.2.6 after applying updates📡 Detection & Monitoring
Log Indicators:
- Multiple failed requests to v2x00.cgi
- Unusual POST requests with long newProname parameter values
- Router reboot events in system logs
Network Indicators:
- Unusual traffic patterns to router management interface
- Multiple connection attempts to port 80/443 from untrusted sources
SIEM Query:
source="router_logs" AND (uri="*/v2x00.cgi*" OR parameter="newProname") AND (bytes>1000 OR status=500)