CVE-2023-40845
📋 TL;DR
This CVE describes a critical buffer overflow vulnerability in Tenda AC6 routers that allows remote attackers to execute arbitrary code. Attackers can exploit this by sending specially crafted requests to the vulnerable function without authentication. 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
Complete device compromise leading to persistent backdoor installation, network traffic interception, lateral movement to other devices, and botnet recruitment.
Likely Case
Remote code execution allowing attackers to modify router settings, intercept traffic, or use the device as a pivot point for further attacks.
If Mitigated
Limited impact if the device is behind a firewall with strict inbound rules and network segmentation prevents lateral movement.
🎯 Exploit Status
Public proof-of-concept code exists in GitHub repositories. The vulnerability requires no authentication and has a straightforward exploitation path.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Tenda's official website for firmware updates
2. Download the latest firmware for AC6 model
3. Access router admin interface
4. Navigate to firmware upgrade section
5. Upload and apply the new firmware
6. Wait for router to reboot
🔧 Temporary Workarounds
Network Segmentation
allIsolate the router from critical internal networks to limit potential damage
Firewall Rules
linuxBlock external access to router management interface
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Replace the vulnerable router with a different model that receives security updates
- Place the router behind a dedicated firewall with strict inbound/outbound rules
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version matches US_AC6V1.0BR_V15.03.05.16_multi_TD01.bin, the device is vulnerable.Check Version:
Login to router admin interface and check System Status or Firmware Upgrade sectionVerify Fix Applied:
Verify firmware version has been updated to a version later than the vulnerable one.📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to router management interface
- Multiple failed login attempts followed by buffer overflow patterns
- Unexpected process creation or system reboots
Network Indicators:
- Unusual outbound connections from router
- Traffic patterns suggesting command and control communication
- Port scanning originating from router
SIEM Query:
source="router_logs" AND (http_uri CONTAINS "sub_34FD0" OR http_user_agent CONTAINS "exploit" OR http_status=500)