CVE-2024-3905
📋 TL;DR
This critical vulnerability in Tenda AC500 routers allows remote attackers to execute arbitrary code via a stack-based buffer overflow in the R7WebsSecurityHandler function. Attackers can exploit this by sending specially crafted password data to the /goform/execCommand endpoint. All users of affected Tenda AC500 routers are at risk.
💻 Affected Systems
- Tenda AC500
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent remote access, network infiltration, data exfiltration, and use as a pivot point for attacking other internal systems.
Likely Case
Remote code execution allowing attackers to install malware, create backdoors, intercept network traffic, or join botnets.
If Mitigated
Limited impact if device is isolated behind firewalls with strict inbound filtering, though lateral movement risk remains if exploited.
🎯 Exploit Status
Public exploit details are available on GitHub, making weaponization straightforward. The vulnerability requires no authentication and has simple exploitation requirements.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available - vendor did not respond to disclosure
Restart Required: Yes
Instructions:
1. Check Tenda website for firmware updates
2. If update available, download and verify checksum
3. Access router admin interface
4. Navigate to firmware upgrade section
5. Upload new firmware file
6. Wait for reboot and verify version
🔧 Temporary Workarounds
Network Segmentation
allIsolate Tenda AC500 routers from critical networks and internet exposure
Access Control Lists
linuxBlock access to vulnerable endpoint /goform/execCommand
iptables -A INPUT -p tcp --dport 80 -m string --string "/goform/execCommand" --algo bm -j DROP
iptables -A INPUT -p tcp --dport 443 -m string --string "/goform/execCommand" --algo bm -j DROP
🧯 If You Can't Patch
- Replace affected Tenda AC500 routers with different vendor equipment
- Implement strict network segmentation to isolate vulnerable devices from critical assets
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is 2.0.1.9(1307), device is vulnerable.Check Version:
Check via router web interface at http://router_ip or using curl: curl -s http://router_ip | grep -i firmwareVerify Fix Applied:
Verify firmware version has changed from 2.0.1.9(1307) to a newer version after update.📡 Detection & Monitoring
Log Indicators:
- Multiple failed requests to /goform/execCommand
- Unusual POST requests with long password parameters
- Router reboot events following web interface access
Network Indicators:
- Unusual outbound connections from router
- Traffic patterns suggesting command and control communication
- Exploit kit signatures targeting Tenda routers
SIEM Query:
source="router_logs" AND (uri="/goform/execCommand" OR password_length>100)🔗 References
- https://github.com/abcdefg-png/IoT-vulnerable/blob/main/Tenda/AC500/R7WebsSecurityHandler.md
- https://vuldb.com/?ctiid.261141
- https://vuldb.com/?id.261141
- https://vuldb.com/?submit.313790
- https://github.com/abcdefg-png/IoT-vulnerable/blob/main/Tenda/AC500/R7WebsSecurityHandler.md
- https://vuldb.com/?ctiid.261141
- https://vuldb.com/?id.261141
- https://vuldb.com/?submit.313790
