CVE-2020-5133
📋 TL;DR
A buffer overflow vulnerability in SonicOS allows remote unauthenticated attackers to cause denial of service by crashing the firewall. This affects SonicWall firewalls running specific vulnerable versions of SonicOS Gen 6 and Gen 7. Organizations using these affected firewall versions are at risk of service disruption.
💻 Affected Systems
- SonicWall firewalls with SonicOS
- SonicOSv virtual appliances
📦 What is this software?
Sonicos by Sonicwall
Sonicos by Sonicwall
Sonicos by Sonicwall
Sonicosv by Sonicwall
⚠️ Risk & Real-World Impact
Worst Case
Complete firewall outage leading to network downtime, loss of internet connectivity, and disruption of all firewall-protected services.
Likely Case
Firewall crash requiring manual reboot, causing temporary network disruption until service is restored.
If Mitigated
Minimal impact if firewalls are patched or protected by network segmentation and intrusion prevention systems.
🎯 Exploit Status
The vulnerability requires no authentication and buffer overflow exploitation is typically straightforward once details are known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: SonicOS Gen 6: 6.5.4.4-44v-21-1452 and later; SonicOS Gen 7: 7.0.1.0 and later
Vendor Advisory: https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2020-0008
Restart Required: Yes
Instructions:
1. Download the latest firmware from MySonicWall portal. 2. Backup current configuration. 3. Upload and install the firmware update. 4. Reboot the firewall. 5. Verify the new version is running.
🔧 Temporary Workarounds
Network Segmentation
allRestrict access to firewall management interfaces to trusted networks only
Intrusion Prevention
allDeploy IPS signatures to detect and block buffer overflow attempts
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach the firewall management interfaces
- Deploy additional security layers like WAF or external firewalls in front of vulnerable devices
🔍 How to Verify
Check if Vulnerable:
Check SonicOS version via web interface (System > Status) or CLI (show version). Compare against affected versions.Check Version:
show version (CLI) or check System > Status in web interfaceVerify Fix Applied:
Verify SonicOS version is updated to patched versions: Gen 6: 6.5.4.4-44v-21-1452+, Gen 7: 7.0.1.0+📡 Detection & Monitoring
Log Indicators:
- Firewall crash/reboot events
- Buffer overflow alerts in system logs
- Unusual traffic patterns to firewall management interface
Network Indicators:
- Multiple connection attempts to firewall management ports (default 443/HTTPS)
- Malformed packets targeting firewall
SIEM Query:
source="sonicwall" AND (event_type="crash" OR event_type="reboot" OR message="*buffer*overflow*")