CVE-2024-3909
📋 TL;DR
A critical stack-based buffer overflow vulnerability in Tenda AC500 routers allows remote attackers to execute arbitrary code by sending specially crafted requests to the /goform/execCommand endpoint. This affects Tenda AC500 routers running firmware version 2.0.1.9(1307). Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Tenda AC500
📦 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
Remote code execution allowing attackers to modify router settings, intercept network traffic, or use the device as a pivot point for further attacks.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering, though internal exploitation risk remains.
🎯 Exploit Status
Public exploit code is available on GitHub. The vulnerability requires no authentication and has straightforward exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: Yes
Instructions:
No official patch available. Contact Tenda support for firmware updates. If unavailable, implement workarounds immediately.
🔧 Temporary Workarounds
Network Access Control
linuxBlock external access to router web interface and management ports
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Endpoint Isolation
allPlace affected routers in isolated network segments
🧯 If You Can't Patch
- Immediately isolate affected devices from internet and critical internal networks
- Implement strict firewall rules to block all inbound traffic to router management interfaces
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface at http://router-ip/ or using command: telnet router-ip (if enabled) and check versionCheck Version:
curl -s http://router-ip/ | grep -i 'firmware version' or check web interface System Status pageVerify Fix Applied:
Verify firmware version has been updated beyond 2.0.1.9(1307) or test if /goform/execCommand endpoint responds to crafted payloads📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/execCommand
- Large payloads in HTTP requests to router
- Multiple failed exploit attempts
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 (url="/goform/execCommand" OR cmdinput=*)🔗 References
- https://github.com/abcdefg-png/IoT-vulnerable/blob/main/Tenda/AC500/formexeCommand.md
- https://vuldb.com/?ctiid.261145
- https://vuldb.com/?id.261145
- https://vuldb.com/?submit.313804
- https://github.com/abcdefg-png/IoT-vulnerable/blob/main/Tenda/AC500/formexeCommand.md
- https://vuldb.com/?ctiid.261145
- https://vuldb.com/?id.261145
- https://vuldb.com/?submit.313804
