CVE-2021-45531
📋 TL;DR
This vulnerability allows authenticated users on NETGEAR D6220 routers to execute arbitrary commands through command injection. Attackers with valid credentials can potentially gain full control of the device. Only NETGEAR D6220 devices running firmware versions before 1.0.0.76 are affected.
💻 Affected Systems
- NETGEAR D6220
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent backdoors, intercept network traffic, pivot to internal networks, or use the device for botnet activities.
Likely Case
Local network attackers with router credentials gain administrative access to modify router settings, intercept traffic, or use the router as a foothold for further attacks.
If Mitigated
With strong authentication and network segmentation, impact is limited to the router itself without lateral movement capabilities.
🎯 Exploit Status
Exploitation requires valid credentials but command injection is straightforward once authenticated.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.0.76
Vendor Advisory: https://kb.netgear.com/000064535/Security-Advisory-for-Post-Authentication-Command-Injection-on-D6220-PSV-2021-0200
Restart Required: Yes
Instructions:
1. Log into router web interface. 2. Navigate to Advanced > Administration > Firmware Update. 3. Check for updates and install version 1.0.0.76 or later. 4. Reboot router after update completes.
🔧 Temporary Workarounds
Restrict Admin Access
allLimit administrative access to trusted IP addresses only
In router web interface: Advanced > Security > Access Control > Allow only specified IP addresses
Change Default Credentials
allUse strong, unique passwords for router administration
In router web interface: Basic > Password
🧯 If You Can't Patch
- Segment router management interface to isolated VLAN
- Implement network monitoring for suspicious router traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface: Basic > Router Information > Firmware VersionCheck Version:
Not applicable - check via web interface onlyVerify Fix Applied:
Confirm firmware version is 1.0.0.76 or higher in router web interface📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in router logs
- Multiple failed login attempts followed by successful login
Network Indicators:
- Unexpected outbound connections from router
- Unusual traffic patterns from router management interface
SIEM Query:
source="router_logs" AND (command="*;*" OR command="*|*" OR command="*`*" OR command="*$(*")