CVE-2021-4144
📋 TL;DR
This vulnerability allows attackers to execute arbitrary operating system commands on TP-Link TL-WR802N V4(JP) routers. Attackers can potentially gain full control of the device by exploiting improper input validation in the web interface. Only users of this specific router model with firmware versions before 211202 are affected.
💻 Affected Systems
- TP-Link TL-WR802N V4(JP)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router allowing attackers to intercept all network traffic, install persistent malware, pivot to internal network devices, and use the router as part of a botnet.
Likely Case
Attackers gain administrative access to the router, change DNS settings to redirect traffic, capture credentials, and potentially compromise connected devices.
If Mitigated
If the router is not internet-facing and network segmentation is in place, impact is limited to the local network segment.
🎯 Exploit Status
Exploitation requires authentication to the router's web interface. The vulnerability is in the web management interface's input validation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 211202 or later
Vendor Advisory: https://www.tp-link.com/jp/support/download/tl-wr802n/#Firmware
Restart Required: Yes
Instructions:
1. Download firmware version 211202 or later from TP-Link Japan website. 2. Log into router web interface. 3. Navigate to System Tools > Firmware Upgrade. 4. Upload the firmware file. 5. Wait for upgrade to complete and router to reboot.
🔧 Temporary Workarounds
Disable remote management
allPrevents external attackers from accessing the web interface
Navigate to Security > Remote Management and disable
Change default credentials
allReduces risk of unauthorized access to management interface
Navigate to System Tools > Password and set strong password
🧯 If You Can't Patch
- Isolate the router on a dedicated network segment with strict firewall rules
- Implement network monitoring for unusual outbound connections from the router
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System Tools > Firmware Upgrade. If version is older than 211202, device is vulnerable.Check Version:
Not applicable - check via web interface onlyVerify Fix Applied:
After updating, verify firmware version shows 211202 or newer in System Tools > Firmware Upgrade page.📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in system logs
- Multiple failed login attempts followed by successful login
- Unexpected firmware modification attempts
Network Indicators:
- Unusual outbound connections from router IP
- DNS queries to suspicious domains from router
- Unexpected port scans originating from router
SIEM Query:
source="router_logs" AND (event_type="command_execution" OR event_type="firmware_change")