CVE-2023-39751
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on TP-Link TL-WR941ND V6 routers via a buffer overflow in the ping functionality. Attackers can exploit this without authentication to gain full control of affected devices. Only TP-Link TL-WR941ND V6 routers are affected.
💻 Affected Systems
- TP-Link TL-WR941ND
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device takeover leading to persistent backdoor installation, network traffic interception, lateral movement to other devices, and botnet recruitment.
Likely Case
Remote code execution allowing attackers to modify router settings, intercept traffic, or use the device as a pivot point for further attacks.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access and proper network segmentation.
🎯 Exploit Status
Public proof-of-concept available. Exploitation requires sending specially crafted HTTP request to /userRpm/PingIframeRpm endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check TP-Link support for latest firmware
Vendor Advisory: https://www.tp-link.com/support/download/tl-wr941nd/v6/
Restart Required: Yes
Instructions:
1. Visit TP-Link support site. 2. Download latest firmware for TL-WR941ND V6. 3. Log into router admin interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload and install new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable remote management
allPrevent external access to router web interface
Log into router > Security > Remote Management > Disable
Block access to vulnerable endpoint
linuxUse firewall rules to block access to /userRpm/PingIframeRpm
iptables -A INPUT -p tcp --dport 80 -m string --string "/userRpm/PingIframeRpm" --algo bm -j DROP
🧯 If You Can't Patch
- Isolate affected routers in separate VLAN with strict firewall rules
- Implement network monitoring for exploitation attempts and block malicious IPs
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under System Tools > Firmware Upgrade. If version is outdated, assume vulnerable.Check Version:
curl -s http://router-ip/ | grep -i firmwareVerify Fix Applied:
After updating firmware, verify version shows latest release. Test by attempting to access /userRpm/PingIframeRpm with malformed parameters.📡 Detection & Monitoring
Log Indicators:
- HTTP requests to /userRpm/PingIframeRpm with abnormal parameter lengths
- Router reboot events after suspicious requests
Network Indicators:
- HTTP POST requests to router IP on port 80 with large pSize parameter
- Unusual outbound connections from router
SIEM Query:
source="router-logs" AND url="/userRpm/PingIframeRpm" AND (param_length>100 OR status_code=500)