CVE-2020-9374
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands on TP-Link TL-WR849N routers by sending shell metacharacters to the traceroute diagnostic feature. It affects TP-Link TL-WR849N devices running firmware version 0.9.1 4.16. Attackers can gain full control of affected routers without authentication.
💻 Affected Systems
- TP-Link TL-WR849N
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of router with persistent backdoor installation, network traffic interception, credential theft, and pivot to internal network devices.
Likely Case
Router takeover leading to DNS hijacking, credential harvesting, and network disruption.
If Mitigated
Limited impact if router is behind firewall with restricted WAN access and regular monitoring.
🎯 Exploit Status
Multiple public exploit scripts available. Exploitation requires sending crafted HTTP requests to the router's web interface.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: No official TP-Link advisory found
Restart Required: No
Instructions:
1. Check TP-Link support site for firmware updates
2. If update available, download from official TP-Link site
3. Log into router admin panel
4. Navigate to System Tools > Firmware Upgrade
5. Upload and apply new firmware
6. Verify version after reboot
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to router web interface
Log into router admin > Security > Remote Management > Disable
Block Diagnostic Ports
linuxRestrict access to router management ports
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Replace affected routers with supported models
- Place routers behind dedicated firewall with strict ingress filtering
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin panel under System Tools > Firmware Upgrade. If version is 0.9.1 4.16, device is vulnerable.Check Version:
curl -s http://router-ip/userRpm/LoginRpm.htm?Save=Save | grep -i firmwareVerify Fix Applied:
Verify firmware version has changed from 0.9.1 4.16. Test traceroute feature with metacharacters (caution: use in isolated environment).📡 Detection & Monitoring
Log Indicators:
- Unusual traceroute requests in router logs
- HTTP requests containing shell metacharacters like ;, |, &, $()
Network Indicators:
- Unexpected outbound connections from router
- DNS queries to suspicious domains
SIEM Query:
source="router.log" AND ("traceroute" AND ("$" OR "|" OR ";" OR "&" OR "`"))🔗 References
- http://packetstormsecurity.com/files/156584/TP-Link-TL-WR849N-Remote-Code-Execution.html
- https://fireshellsecurity.team/hack-n-routers/
- https://github.com/ElberTavares/routers-exploit/tree/master/tp-link
- http://packetstormsecurity.com/files/156584/TP-Link-TL-WR849N-Remote-Code-Execution.html
- https://fireshellsecurity.team/hack-n-routers/
- https://github.com/ElberTavares/routers-exploit/tree/master/tp-link
