CVE-2024-46597
📋 TL;DR
CVE-2024-46597 is a buffer overflow vulnerability in Draytek Vigor 3910 routers affecting the sPubKey parameter in dialin.cgi. Attackers can exploit this by sending crafted inputs to cause 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, extended service disruption, and potential for remote code execution if the overflow can be controlled precisely.
Likely Case
Router becomes unresponsive, requiring manual reboot, causing temporary network outage for connected users and services.
If Mitigated
Limited to isolated DoS affecting only the management interface if proper network segmentation is implemented.
🎯 Exploit Status
Buffer overflow in web parameter suggests straightforward exploitation via HTTP requests to the vulnerable endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Monitor Draytek security advisories for patch release. 2. Download firmware update from vendor portal. 3. Backup configuration. 4. Apply firmware update via web interface. 5. Reboot device. 6. Verify version update.
🔧 Temporary Workarounds
Restrict Web Interface Access
allLimit access to the router's web management interface to trusted IP addresses only.
Configure firewall rules to allow only specific source IPs to TCP ports 80/443 on the router.
Disable Unnecessary Services
allDisable remote management features if not required.
Navigate to Management > Access Control > Remote Management in web interface and disable.
🧯 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 via web interface: System Maintenance > Firmware Information. If version is v4.3.2.6, device is vulnerable.Check Version:
No CLI command; check via web interface or SNMP if configured.Verify Fix Applied:
After patching, verify firmware version is updated to a version later than v4.3.2.6.📡 Detection & Monitoring
Log Indicators:
- Multiple HTTP POST requests to /cgi-bin/dialin.cgi with large sPubKey parameter values
- Router crash/reboot logs in system event logs
Network Indicators:
- Unusual HTTP traffic patterns to router management interface
- Increased packet size in requests to dialin.cgi
SIEM Query:
source="router_logs" AND url="/cgi-bin/dialin.cgi" AND (param_size>1000 OR status=500)