CVE-2021-45735
📋 TL;DR
This vulnerability allows attackers to intercept administrator credentials for TOTOLINK X5000R routers because the admin interface uses unencrypted HTTP instead of HTTPS. Anyone using the affected router version with default settings is vulnerable to credential theft.
💻 Affected Systems
- TOTOLINK X5000R
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain full administrative control of the router, allowing them to reconfigure network settings, intercept all traffic, install malware, or use the device as part of a botnet.
Likely Case
Attackers on the same network capture admin credentials and gain unauthorized access to router configuration, potentially changing DNS settings or firewall rules.
If Mitigated
With proper network segmentation and monitoring, impact is limited to credential exposure requiring password reset and investigation.
🎯 Exploit Status
Exploitation requires network access to capture HTTP traffic; tools like Wireshark or tcpdump can capture credentials in plaintext.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: No
Instructions:
No official patch available. Check TOTOLINK website for firmware updates and upgrade to latest version if available.
🔧 Temporary Workarounds
Disable HTTP admin access
allConfigure router to use HTTPS only for admin interface if supported
Network segmentation
allIsolate router management interface to separate VLAN
🧯 If You Can't Patch
- Change admin password immediately and use strong, unique credentials
- Monitor router logs for unauthorized access attempts and network traffic for credential capture
🔍 How to Verify
Check if Vulnerable:
Check if admin interface URL starts with http:// instead of https:// when logging inCheck Version:
Login to router admin interface and check firmware version in system settingsVerify Fix Applied:
Verify admin interface forces HTTPS and credentials are transmitted over encrypted connection📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts
- Successful logins from unexpected IP addresses
- Configuration changes from unauthorized users
Network Indicators:
- HTTP traffic to router admin port containing 'POST /cgi-bin/login.cgi' with plaintext credentials
- ARP spoofing or MITM attacks targeting router IP
SIEM Query:
source_ip="router_ip" AND (http_method="POST" AND uri="/cgi-bin/login.cgi")