CVE-2021-46007
📋 TL;DR
CVE-2021-46007 is a critical command injection vulnerability in TOTOLINK A3100R routers that allows attackers to execute arbitrary operating system commands. The vulnerability exists in the web interface's ping functionality where user input isn't properly sanitized. This affects all users running the vulnerable firmware version.
💻 Affected Systems
- TOTOLINK A3100R
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to install malware, create persistent backdoors, pivot to internal networks, and brick the device.
Likely Case
Remote code execution leading to device takeover, credential theft, DNS hijacking, and participation in botnets.
If Mitigated
Limited impact if network segmentation isolates the router and external access is disabled.
🎯 Exploit Status
Exploitation requires no authentication and uses simple command injection techniques. Public proof-of-concept code exists.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Later than V5.9c.4577
Vendor Advisory: http://totolink.com
Restart Required: Yes
Instructions:
1. Log into TOTOLINK support portal. 2. Download latest firmware for A3100R. 3. Access router web interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload new firmware file. 6. Wait for automatic reboot.
🔧 Temporary Workarounds
Disable WAN Management Access
allPrevent external access to the vulnerable web interface
Access router web interface > Advanced > System > Remote Management > Disable
Network Segmentation
allIsolate router management interface to separate VLAN
🧯 If You Can't Patch
- Implement strict firewall rules blocking all external access to router management interface (typically ports 80/443)
- Deploy network-based intrusion prevention system (IPS) with command injection detection rules
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System Status > Firmware VersionCheck Version:
curl -s http://router-ip/cgi-bin/luci/ | grep -i versionVerify Fix Applied:
Verify firmware version is newer than V5.9c.4577 and test ping functionality with injection attempts📡 Detection & Monitoring
Log Indicators:
- Unusual ping commands in system logs
- Multiple failed login attempts followed by ping commands
- Commands with special characters in web access logs
Network Indicators:
- Unusual outbound connections from router
- Ping packets containing command syntax
- HTTP requests to management interface with shell metacharacters
SIEM Query:
source="router.log" AND ("ping" AND ("|" OR ";" OR "`" OR "$" OR "&"))