CVE-2021-44627
📋 TL;DR
This CVE describes a critical buffer overflow vulnerability in TP-LINK WR-886N routers, allowing remote attackers to execute arbitrary code via a crafted POST request to the /cloud_config/router_post/get_reset_pwd_veirfy_code endpoint. It affects users of TP-LINK WR-886N routers running specific vulnerable firmware versions, potentially enabling full system compromise.
💻 Affected Systems
- TP-LINK WR-886N
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full remote code execution leading to complete router takeover, data theft, network pivoting, and persistent backdoor installation.
Likely Case
Router compromise allowing attackers to intercept traffic, modify DNS settings, or launch attacks on internal networks.
If Mitigated
Limited impact if isolated or patched, but potential for denial-of-service or configuration changes.
🎯 Exploit Status
Public proof-of-concept code is available, making exploitation straightforward for attackers with network access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not publicly known
Restart Required: No
Instructions:
Check TP-LINK's official website or support for firmware updates; if unavailable, consider workarounds or replacement.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to the router's web interface by disabling remote management features in the router settings.
Block Vulnerable Endpoint
linuxUse firewall rules to block access to the /cloud_config/router_post/get_reset_pwd_veirfy_code endpoint.
iptables -A INPUT -p tcp --dport 80 -m string --string "/cloud_config/router_post/get_reset_pwd_veirfy_code" --algo bm -j DROP
🧯 If You Can't Patch
- Isolate the router on a dedicated network segment to limit potential lateral movement.
- Monitor network traffic for unusual POST requests to the vulnerable endpoint and implement intrusion detection.
🔍 How to Verify
Check if Vulnerable:
Access the router's web interface, navigate to firmware version in settings, and check if it matches the affected version (20190826 2.3.8).Check Version:
Log into router web UI and check system info, or use curl: curl -s http://router-ip/ | grep -i versionVerify Fix Applied:
Verify firmware has been updated to a version not listed as vulnerable; test by attempting to send a crafted POST request to the endpoint and checking for error or crash.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /cloud_config/router_post/get_reset_pwd_veirfy_code in router logs
- System crashes or reboots following such requests
Network Indicators:
- HTTP traffic with long or malformed payloads to the vulnerable endpoint
- Unexpected outbound connections from the router post-exploit
SIEM Query:
source="router_logs" AND uri="/cloud_config/router_post/get_reset_pwd_veirfy_code" AND method="POST"