CVE-2021-34977
📋 TL;DR
This vulnerability allows network-adjacent attackers to bypass authentication on NETGEAR R7000 routers by exploiting a flaw in SOAP request processing. Attackers can reset the admin password without authentication, gaining full control of affected routers. Only users with NETGEAR R7000 routers running vulnerable firmware are affected.
💻 Affected Systems
- NETGEAR R7000
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of router with admin access, allowing traffic interception, DNS manipulation, network reconnaissance, and installation of persistent malware.
Likely Case
Unauthorized admin access leading to network traffic monitoring, credential theft, and potential lateral movement to connected devices.
If Mitigated
Limited impact if router is behind additional firewalls, uses strong unique passwords, and has network segmentation isolating it from critical systems.
🎯 Exploit Status
Exploit requires sending crafted SOAP requests to the router's web interface. No authentication needed. Weaponized exploits exist in the wild.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware version 1.0.11.130 or later
Vendor Advisory: https://kb.netgear.com/000064046/Security-Advisory-for-Authentication-Bypass-on-Some-Routers-and-DSL-Modem-Routers-PSV-2021-0134
Restart Required: Yes
Instructions:
1. Log into router admin interface. 2. Navigate to Advanced > Administration > Firmware Update. 3. Check for updates or manually download latest firmware from NETGEAR support site. 4. Upload and install firmware. 5. Router will reboot automatically.
🔧 Temporary Workarounds
Disable Remote Management
allPrevents external exploitation by disabling web interface access from WAN
Network Segmentation
allIsolate router management interface to dedicated VLAN
🧯 If You Can't Patch
- Replace router with supported model running patched firmware
- Implement strict network access controls to limit who can reach router management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under Advanced > Administration > Firmware Update. If version is 1.0.11.116_10.2.100 or earlier, router is vulnerable.Check Version:
curl -k https://[router-ip]/currentsetting.htm | grep firmwareVerify Fix Applied:
Verify firmware version is 1.0.11.130 or later in admin interface. Test password reset functionality requires authentication.📡 Detection & Monitoring
Log Indicators:
- Unusual SOAP requests to router management interface
- Multiple failed authentication attempts followed by successful admin login from new IP
- Password reset logs without prior authentication
Network Indicators:
- Unusual HTTP POST requests to /soap/server_sa/ endpoints
- Traffic to router management interface from unexpected internal IPs
SIEM Query:
source="router.log" AND ("SOAP" OR "password" OR "reset") AND NOT user="admin"🔗 References
- https://kb.netgear.com/000064046/Security-Advisory-for-Authentication-Bypass-on-Some-Routers-and-DSL-Modem-Routers-PSV-2021-0134
- https://www.zerodayinitiative.com/advisories/ZDI-21-1239/
- https://kb.netgear.com/000064046/Security-Advisory-for-Authentication-Bypass-on-Some-Routers-and-DSL-Modem-Routers-PSV-2021-0134
- https://www.zerodayinitiative.com/advisories/ZDI-21-1239/
