CVE-2023-40837
📋 TL;DR
This vulnerability allows remote command execution on Tenda AC6 routers by exploiting unfiltered input in the formSetIptv function. Attackers can execute arbitrary commands with root privileges by manipulating the 'list' and 'vlanId' parameters. All users running vulnerable firmware versions are affected.
💻 Affected Systems
- Tenda AC6 router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router compromise allowing attackers to intercept traffic, install persistent malware, pivot to internal networks, or brick the device.
Likely Case
Router takeover leading to DNS hijacking, credential theft from network traffic, or participation in botnets.
If Mitigated
Limited impact if network segmentation isolates the router and external access is disabled.
🎯 Exploit Status
Public proof-of-concept exists in GitHub repository. Exploitation requires sending crafted HTTP requests to the router's web interface.
🛠️ 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. 3. Access router admin interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload new firmware file. 6. Wait for reboot.
🔧 Temporary Workarounds
Disable remote management
allPrevent external access to router web interface
Network segmentation
allIsolate router management interface from user networks
🧯 If You Can't Patch
- Replace router with different model/brand
- Implement strict firewall rules blocking all external access to router management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under System Status or System Tools. If version is US_AC6V1.0BR_V15.03.05.16 or earlier, likely vulnerable.Check Version:
curl -s http://router-ip/goform/getStatus | grep versionVerify Fix Applied:
Verify firmware version has been updated to a version later than US_AC6V1.0BR_V15.03.05.16. Test by attempting to access formSetIptv endpoint with test payloads.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/setIptv
- Commands executed from web interface process
- Multiple failed login attempts followed by successful command execution
Network Indicators:
- HTTP requests containing shell metacharacters in parameters
- Outbound connections from router to suspicious IPs
- Unusual DNS queries from router
SIEM Query:
source="router_logs" AND (uri="/goform/setIptv" OR (method="POST" AND uri CONTAINS "goform" AND (param CONTAINS "|" OR param CONTAINS ";" OR param CONTAINS "`")))