CVE-2023-40841
📋 TL;DR
CVE-2023-40841 is a critical buffer overflow vulnerability in Tenda AC6 routers that allows remote attackers to execute arbitrary code or cause denial of service by sending specially crafted requests to the 'add_white_node' function. This affects users of Tenda AC6 routers with vulnerable firmware versions. Attackers can potentially gain full control of affected devices.
💻 Affected Systems
- Tenda AC6
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, lateral movement to internal networks, persistent backdoor installation, and botnet recruitment.
Likely Case
Router compromise allowing traffic interception, DNS hijacking, credential theft, and denial of service to connected devices.
If Mitigated
Limited to denial of service if proper network segmentation and firewall rules prevent external access to router management interfaces.
🎯 Exploit Status
Public proof-of-concept available in GitHub repository. Exploitation requires network access to router management 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 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 management interface
Access router web interface > Advanced > System Tools > Remote Management > Disable
Network Segmentation
linuxIsolate router management interface to trusted network
iptables -A INPUT -p tcp --dport 80 -s ! TRUSTED_NETWORK -j DROP
iptables -A INPUT -p tcp --dport 443 -s ! TRUSTED_NETWORK -j DROP
🧯 If You Can't Patch
- Replace vulnerable router with updated model or different vendor
- Implement strict network access controls to limit exposure of router management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface: System Status > Firmware Version. If version is US_AC6V1.0BR_V15.03.05.16_multi_TD01.bin or earlier, device is vulnerable.Check Version:
curl -s http://router-ip/goform/getStatus | grep firmwareVerVerify Fix Applied:
Verify firmware version has been updated to a version later than US_AC6V1.0BR_V15.03.05.16_multi_TD01.bin📡 Detection & Monitoring
Log Indicators:
- Unusual requests to /goform/addWhiteNode endpoint
- Multiple failed buffer overflow attempts in system logs
- Unexpected process crashes or restarts
Network Indicators:
- Unusual traffic patterns to router management ports (80, 443)
- POST requests to /goform/addWhiteNode with large payloads
- Traffic from unexpected sources to router IP
SIEM Query:
source="router.log" AND ("addWhiteNode" OR "buffer overflow" OR "segmentation fault")