CVE-2023-40839
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands on Tenda AC6 routers by sending specially crafted requests to the 'formSetIptv' function. Attackers can gain full control of affected devices without authentication. All users running vulnerable firmware versions are affected.
💻 Affected Systems
- Tenda AC6 wireless router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device takeover allowing installation of persistent malware, network traffic interception, lateral movement to internal networks, and use as botnet nodes.
Likely Case
Router compromise leading to DNS hijacking, credential theft from network traffic, and denial of service attacks.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Public proof-of-concept exists in GitHub repositories. Exploitation requires sending HTTP POST requests with malicious parameters to the vulnerable endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Tenda website for firmware updates
2. Download latest firmware for AC6 model
3. Access router web interface
4. Navigate to System Tools > Firmware Upgrade
5. Upload and install new firmware
6. Reboot router
🔧 Temporary Workarounds
Disable remote management
allPrevent external access to router web interface
Network segmentation
allIsolate router management interface to trusted network
🧯 If You Can't Patch
- Disable UPnP and ensure router is behind a firewall with strict inbound rules
- Implement network monitoring for unusual outbound connections from router
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System Status. If version is V15.03.05.16 or earlier, device is likely vulnerable.Check Version:
Login to router web interface and check System Status page, or use: curl -s http://router-ip/goform/getStatus | grep versionVerify Fix Applied:
Verify firmware version has been updated to a version later than V15.03.05.16. Test by attempting to access the vulnerable endpoint with test payloads.📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /goform/setIptv with unusual parameters
- Command execution attempts in system logs
- Unusual process creation from web server
Network Indicators:
- Unusual outbound connections from router IP
- DNS queries to suspicious domains from router
- Unexpected SSH/Telnet connections originating from router
SIEM Query:
source="router_logs" AND (uri="/goform/setIptv" OR (method="POST" AND uri CONTAINS "setIptv"))