CVE-2022-20761
📋 TL;DR
An unauthenticated attacker on the same network can send crafted traffic to Cisco CGR1K routers, causing the integrated wireless access point to stop processing traffic. This denial-of-service condition requires manual device reload to restore functionality. Only Cisco 1000 Series Connected Grid Routers with specific software versions are affected.
💻 Affected Systems
- Cisco 1000 Series Connected Grid Router (CGR1K)
📦 What is this software?
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⚠️ Risk & Real-World Impact
Worst Case
Complete wireless AP service disruption requiring manual router reload, potentially causing extended downtime for connected industrial/utility systems.
Likely Case
Temporary wireless network outage affecting connected devices until manual intervention restores service.
If Mitigated
No impact if patched or if wireless AP functionality is disabled on affected devices.
🎯 Exploit Status
No public exploit code available. Crafting malicious packets requires understanding of wireless AP protocols.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Cisco IOS XE Software Release 17.9.1 or later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cgr1k-ap-dos-mSZR4QVh
Restart Required: Yes
Instructions:
1. Download Cisco IOS XE Software Release 17.9.1 or later from Cisco Software Center. 2. Backup current configuration. 3. Upload new image to router. 4. Reload device to apply update.
🔧 Temporary Workarounds
Disable Integrated Wireless AP
allTurn off the vulnerable wireless access point functionality if not required.
configure terminal
no dot11 wlan 1
end
write memory
Implement Network Segmentation
allIsolate CGR1K management interfaces from untrusted networks.
🧯 If You Can't Patch
- Implement strict network access controls to limit adjacent attacker access
- Monitor for unusual traffic patterns targeting wireless AP interfaces
🔍 How to Verify
Check if Vulnerable:
Check IOS XE version: 'show version' and verify if running release prior to 17.9.1 with wireless AP enabled.Check Version:
show version | include VersionVerify Fix Applied:
After upgrade, run 'show version' to confirm IOS XE 17.9.1 or later is installed.📡 Detection & Monitoring
Log Indicators:
- Wireless AP service stopped unexpectedly
- High volume of malformed packets to AP interface
- Device reload events
Network Indicators:
- Unusual packet patterns targeting port 5246/UDP (CAPWAP) or wireless management ports
- Sudden drop in wireless traffic from affected router
SIEM Query:
source="cgr1k" AND (event_type="ap_failure" OR message="*wireless*stop*" OR message="*reload*")