CVE-2021-1285
📋 TL;DR
This vulnerability in Cisco products allows an unauthenticated attacker on the same network to send malicious Ethernet frames that exhaust disk space, causing a denial of service. Affected devices may become unable to boot or allow administrator logins, requiring manual recovery. The vulnerability impacts multiple Cisco products using the Snort detection engine.
💻 Affected Systems
- Multiple Cisco products using Snort detection engine
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Device becomes completely inoperable, requiring manual intervention and potential hardware replacement if disk corruption occurs.
Likely Case
Device runs out of disk space, preventing administrative access and requiring Cisco TAC assistance for recovery.
If Mitigated
If patched, no impact. If unpatched but isolated, limited to adjacent attackers only.
🎯 Exploit Status
Exploitation requires sending crafted Ethernet frames from adjacent network position. No authentication needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Refer to Cisco advisory for specific fixed versions per product
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort-ethernet-dos-HGXgJH8n
Restart Required: Yes
Instructions:
1. Identify affected products and versions from Cisco advisory. 2. Download appropriate fixed software from Cisco. 3. Apply update following Cisco upgrade procedures. 4. Reboot affected devices.
🔧 Temporary Workarounds
No workarounds available
allCisco states there are no workarounds for this vulnerability
🧯 If You Can't Patch
- Isolate affected devices to trusted network segments only
- Implement strict network segmentation to limit adjacent attacker access
🔍 How to Verify
Check if Vulnerable:
Check device model and software version against Cisco advisory listCheck Version:
Device-specific commands (e.g., 'show version' on Cisco CLI)Verify Fix Applied:
Verify software version matches fixed versions in Cisco advisory📡 Detection & Monitoring
Log Indicators:
- Disk space exhaustion alerts
- Snort process failures
- System crash logs
Network Indicators:
- Unusual Ethernet frame patterns targeting affected devices
SIEM Query:
Search for disk space alerts OR process crashes on Cisco devices with Snort enabled