CVE-2021-38528
📋 TL;DR
This vulnerability allows unauthenticated attackers to execute arbitrary commands on affected NETGEAR devices via command injection. It affects multiple NETGEAR router and gateway models running vulnerable firmware versions. Attackers can exploit this remotely without any credentials.
💻 Affected Systems
- NETGEAR D8500
- NETGEAR R6900P
- NETGEAR R7000P
- NETGEAR R7100LG
- NETGEAR WNDR3400v3
- NETGEAR XR300
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent malware, intercept all network traffic, pivot to internal networks, or brick the device.
Likely Case
Attackers gain full control of the router to redirect traffic, steal credentials, or use as a foothold for further attacks.
If Mitigated
If patched, no impact. If isolated from internet, limited to internal network attacks only.
🎯 Exploit Status
Public exploit code exists, making this easily weaponizable. No authentication required for exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: D8500: 1.0.3.58+, R6900P: 1.3.2.132+, R7000P: 1.3.2.132+, R7100LG: 1.0.0.64+, WNDR3400v3: 1.0.1.38+, XR300: 1.0.3.56+
Vendor Advisory: https://kb.netgear.com/000063781/Security-Advisory-for-Pre-Authentication-Command-Injection-on-Some-Gateways-and-Routers-PSV-2020-0297
Restart Required: Yes
Instructions:
1. Log into router admin interface. 2. Navigate to Advanced > Administration > Firmware Update. 3. Check for updates. 4. If update available, download and install. 5. Router will reboot automatically.
🔧 Temporary Workarounds
Disable Remote Management
allPrevents external attackers from accessing vulnerable interfaces
Network Segmentation
allIsolate affected devices from internet using firewall rules
🧯 If You Can't Patch
- Replace affected devices with patched models or different vendors
- Implement strict network segmentation and firewall rules to limit device exposure
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under Advanced > Administration > Firmware UpdateCheck Version:
Check via web interface: Advanced > Administration > Firmware UpdateVerify Fix Applied:
Verify firmware version matches or exceeds patched versions listed in vendor advisory📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in system logs
- Multiple failed login attempts followed by successful command execution
- Unexpected system reboots or configuration changes
Network Indicators:
- Unusual outbound connections from router
- DNS hijacking or traffic redirection
- Unexpected SSH/Telnet connections to router
SIEM Query:
source="router_logs" AND (command="*;*" OR command="*|*" OR command="*`*" OR command="*$(*")