CVE-2023-40843
📋 TL;DR
This CVE describes a critical buffer overflow vulnerability in Tenda AC6 routers. Attackers can exploit this to execute arbitrary code or cause denial of service by sending specially crafted requests to the vulnerable function. All users running the affected firmware version are at risk.
💻 Affected Systems
- Tenda AC6 router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, network infiltration, and persistent backdoor installation.
Likely Case
Router crash causing denial of service, requiring physical reset and temporary network disruption.
If Mitigated
Limited impact if network segmentation isolates the router and external access is restricted.
🎯 Exploit Status
Public proof-of-concept exists in GitHub repositories. The buffer overflow appears to be straightforward to trigger.
🛠️ 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 admin interface
4. Upload and apply firmware update
5. Reboot router
🔧 Temporary Workarounds
Disable remote management
allPrevent external access to router administration interface
Network segmentation
allIsolate router management interface to separate VLAN
🧯 If You Can't Patch
- Replace vulnerable router with different model or manufacturer
- Implement strict firewall rules to block all external access to router management interface
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is US_AC6V1.0BR_V15.03.05.16_multi_TD01.bin, device is vulnerable.Check Version:
Login to router admin interface and check System Status or Firmware Update sectionVerify Fix Applied:
Verify firmware version has changed from vulnerable version. Test with known exploit payloads if possible.📡 Detection & Monitoring
Log Indicators:
- Multiple connection attempts to router management port
- Unusual traffic patterns to router IP
- Router crash/reboot events in system logs
Network Indicators:
- Unusual payloads sent to router management port (typically 80/443)
- Traffic patterns matching known exploit signatures
SIEM Query:
source_ip="router_ip" AND (port=80 OR port=443) AND payload_size>normal_threshold