CVE-2024-4020
📋 TL;DR
A critical buffer overflow vulnerability in Tenda FH1206 routers allows remote attackers to execute arbitrary code by manipulating the 'entrys' parameter in the fromAddressNat function. This affects Tenda FH1206 routers running firmware version 1.2.0.8(8155). Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Tenda FH1206
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, lateral movement to internal networks, installation of persistent malware, and data exfiltration.
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 device is behind proper network segmentation, firewalls, and intrusion prevention systems that block exploitation attempts.
🎯 Exploit Status
Exploit details have been publicly disclosed, making weaponization likely. The vulnerability requires no authentication and has straightforward exploitation.
🛠️ 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 install via web interface 3. Reboot router after update 4. Verify firmware version changed from 1.2.0.8(8155)
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected routers from critical networks and limit access to management interface
Access Control Lists
allImplement firewall rules to restrict access to the vulnerable endpoint (/goform/addressNat)
🧯 If You Can't Patch
- Replace affected routers with different models or vendors
- Implement strict network segmentation and monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Access router web interface, navigate to System Status or About page, check firmware version matches 1.2.0.8(8155)Check Version:
curl -s http://router-ip/goform/getStatus | grep version (if API accessible)Verify Fix Applied:
Verify firmware version has changed from 1.2.0.8(8155) to a newer version📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/addressNat
- Multiple failed buffer overflow attempts
- Unexpected router reboots or configuration changes
Network Indicators:
- Unusual traffic patterns from router IP
- Outbound connections from router to suspicious IPs
- HTTP requests with long 'entrys' parameter values
SIEM Query:
source="router_logs" AND (url="/goform/addressNat" OR (http_method="POST" AND uri CONTAINS "addressNat"))🔗 References
- https://palm-vertebra-fe9.notion.site/fromAddressNat_entrys-b04d5356e5f04e30b37cb9037b94e1b2
- https://vuldb.com/?ctiid.261671
- https://vuldb.com/?id.261671
- https://vuldb.com/?submit.316036
- https://palm-vertebra-fe9.notion.site/fromAddressNat_entrys-b04d5356e5f04e30b37cb9037b94e1b2
- https://vuldb.com/?ctiid.261671
- https://vuldb.com/?id.261671
- https://vuldb.com/?submit.316036
