CVE-2022-27646
📋 TL;DR
This vulnerability allows network-adjacent attackers to bypass authentication and execute arbitrary code with root privileges on NETGEAR R6700v3 routers by exploiting a stack-based buffer overflow in the circled daemon. Attackers can achieve remote code execution by sending a specially crafted circleinfo.txt file. Only users of specific NETGEAR router models with vulnerable firmware versions are affected.
💻 Affected Systems
- NETGEAR R6700v3
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router with root-level code execution, allowing attackers to intercept all network traffic, install persistent malware, pivot to internal networks, and permanently brick the device.
Likely Case
Router compromise leading to network traffic interception, DNS hijacking, credential theft, and installation of backdoors for persistent access.
If Mitigated
Limited impact if proper network segmentation, firewall rules, and intrusion detection systems prevent lateral movement from compromised devices.
🎯 Exploit Status
Authentication bypass exists but requires network adjacency. ZDI advisory suggests exploit development is feasible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware versions after 1.0.4.120_10.0.91
Vendor Advisory: https://kb.netgear.com/000064721/Security-Advisory-for-Multiple-Vulnerabilities-on-Multiple-Products-PSV-2021-0324
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 circled daemon
linuxTemporarily disable the vulnerable circled service if not needed
killall circled
chmod -x /usr/sbin/circled
Network segmentation
allIsolate router management interface to trusted network segment only
🧯 If You Can't Patch
- Segment router to isolated VLAN with strict firewall rules preventing access from untrusted networks
- Implement network monitoring and intrusion detection for suspicious traffic to/from router management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under Advanced > Administration > Firmware UpdateCheck Version:
ssh admin@router-ip 'cat /etc/version' or check web interfaceVerify Fix Applied:
Verify firmware version is newer than 1.0.4.120_10.0.91 and attempt to access circled service to confirm it's patched or disabled📡 Detection & Monitoring
Log Indicators:
- Unusual authentication attempts to router admin interface
- Large or malformed circleinfo.txt file transfers
- Process crashes of circled daemon
Network Indicators:
- Unusual traffic to router management ports (typically 80/443)
- Suspicious file transfers to circled service port
SIEM Query:
source="router-logs" AND (event="authentication_failure" OR process="circled" AND status="crashed")🔗 References
- https://kb.netgear.com/000064721/Security-Advisory-for-Multiple-Vulnerabilities-on-Multiple-Products-PSV-2021-0324
- https://www.zerodayinitiative.com/advisories/ZDI-22-523/
- https://kb.netgear.com/000064721/Security-Advisory-for-Multiple-Vulnerabilities-on-Multiple-Products-PSV-2021-0324
- https://www.zerodayinitiative.com/advisories/ZDI-22-523/
