CVE-2021-45623
📋 TL;DR
This vulnerability allows unauthenticated attackers to execute arbitrary commands on affected NETGEAR routers via command injection. It affects R7800, R9000, and XR500 models running outdated firmware versions. Attackers can exploit this without any credentials.
💻 Affected Systems
- NETGEAR R7800
- NETGEAR R9000
- NETGEAR XR500
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full router compromise allowing attacker to intercept all network traffic, install persistent malware, pivot to internal networks, and brick the device.
Likely Case
Router takeover leading to DNS hijacking, credential theft from network traffic, and installation of backdoors for persistent access.
If Mitigated
Limited impact if router is behind firewall with restricted WAN access, though local network attacks remain possible.
🎯 Exploit Status
Exploitation requires network access to router's web interface. No authentication needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: R7800 1.0.2.74+, R9000 1.0.5.2+, XR500 2.3.2.66+
Vendor Advisory: https://kb.netgear.com/000064449/Security-Advisory-for-Pre-Authentication-Command-Injection-on-Some-Routers-PSV-2019-0203
Restart Required: Yes
Instructions:
1. Log into router admin interface. 2. Navigate to Advanced > Administration > Firmware Update. 3. Check for updates. 4. Download and install latest firmware. 5. Reboot router after installation.
🔧 Temporary Workarounds
Disable Remote Management
allPrevents external attackers from accessing router interface
Restrict WAN Access
allUse firewall rules to block external access to router admin interface
🧯 If You Can't Patch
- Replace affected routers with patched models or different vendors
- Place routers behind dedicated firewall with strict inbound rules
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under Advanced > Administration > Firmware UpdateCheck Version:
Login to router web interface and navigate to Advanced > Administration > Firmware Update pageVerify Fix Applied:
Confirm firmware version matches or exceeds patched versions: R7800 >= 1.0.2.74, R9000 >= 1.0.5.2, XR500 >= 2.3.2.66📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in router logs
- Multiple failed authentication attempts followed by successful command execution
- Unexpected process creation
Network Indicators:
- Unusual outbound connections from router
- DNS queries to suspicious domains
- Unexpected traffic redirection
SIEM Query:
source="router_logs" AND ("command injection" OR "unauthorized access" OR "shell execution")