CVE-2024-46582
📋 TL;DR
This vulnerability allows attackers to trigger a buffer overflow in Draytek Vigor 3910 routers by sending crafted input to the sSrvAddr parameter in v2x00.cgi. This causes a Denial of Service (DoS), potentially crashing the device. Organizations using Draytek Vigor 3910 routers with vulnerable firmware are affected.
💻 Affected Systems
- Draytek Vigor 3910
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device crash requiring physical reboot, disrupting all network services and connectivity for the affected network segment.
Likely Case
Router becomes unresponsive, requiring manual reboot and causing temporary network outage.
If Mitigated
If properly segmented and monitored, impact limited to isolated network segment with quick detection and recovery.
🎯 Exploit Status
Buffer overflow vulnerabilities in web interfaces are often easily exploitable with publicly available tools.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Draytek website for security advisories. 2. Download latest firmware if available. 3. Backup router configuration. 4. Upload and install new firmware via web interface. 5. Reboot router.
🔧 Temporary Workarounds
Disable vulnerable CGI endpoint
linuxBlock access to v2x00.cgi if not required for functionality
iptables -A INPUT -p tcp --dport 80 -m string --string "v2x00.cgi" --algo bm -j DROP
iptables -A INPUT -p tcp --dport 443 -m string --string "v2x00.cgi" --algo bm -j DROP
Network segmentation
allRestrict access to router management interface to trusted networks only
🧯 If You Can't Patch
- Implement strict network ACLs to limit access to router management interface
- Deploy WAF or IPS with buffer overflow detection rules
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface: System Maintenance > Firmware InformationCheck Version:
Not applicable - check via web interfaceVerify Fix Applied:
Verify firmware version is updated beyond v4.3.2.6📡 Detection & Monitoring
Log Indicators:
- Multiple failed requests to v2x00.cgi
- Router crash/reboot events in system logs
- Unusual long strings in HTTP requests
Network Indicators:
- HTTP requests with unusually long sSrvAddr parameters
- Traffic patterns indicating buffer overflow attempts
SIEM Query:
source="router_logs" AND (uri="*v2x00.cgi*" AND (param_length>100 OR status=500))