CVE-2021-27215
📋 TL;DR
This vulnerability allows authentication bypass in genua genugate firewall appliances. Attackers can log into admin panels as any user, including root with highest privileges, by manipulating authentication data. Affects genugate appliances with vulnerable web interfaces exposed.
💻 Affected Systems
- genua genugate firewall appliances
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full administrative compromise allowing firewall rule modification, traffic interception, network pivoting, and complete system takeover.
Likely Case
Unauthorized administrative access leading to firewall configuration changes, network monitoring, and credential harvesting.
If Mitigated
Limited impact with proper network segmentation, but still potential for initial foothold in segmented zones.
🎯 Exploit Status
Authentication bypass requires specific manipulation of authentication data but no credentials needed. Exploit details are documented in security advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 9.0 Z p19, 9.6 p7, or 10.1 p4 depending on version
Vendor Advisory: https://kunde.genua.de/en/overview/genugate.html
Restart Required: Yes
Instructions:
1. Identify current genugate version. 2. Download appropriate patch from genua customer portal. 3. Apply patch following vendor instructions. 4. Reboot appliance. 5. Verify patch installation.
🔧 Temporary Workarounds
Disable vulnerable web interfaces
allTemporarily disable Admin, Userweb, and Sidechannel web interfaces until patching
Use genugate CLI: configure web-interface disable
Restrict network access
allLimit access to web interfaces using firewall rules to trusted IPs only
Use genugate firewall rules to restrict 443/tcp to management networks
🧯 If You Can't Patch
- Implement strict network segmentation to isolate genugate management interfaces
- Enable multi-factor authentication if supported and monitor for unauthorized access attempts
🔍 How to Verify
Check if Vulnerable:
Check genugate version via web interface or CLI. If version matches affected range and web interfaces are enabled, system is vulnerable.Check Version:
ssh admin@genugate show versionVerify Fix Applied:
Verify version shows patched release (9.0 Z p19, 9.6 p7, or 10.1 p4). Test authentication with invalid credentials to confirm bypass is fixed.📡 Detection & Monitoring
Log Indicators:
- Failed authentication attempts followed by successful login from same IP
- Root/admin logins from unusual IPs or locations
- Multiple authentication method changes in short time
Network Indicators:
- HTTP/HTTPS requests to /login with manipulated authentication parameters
- Unusual admin panel access patterns
SIEM Query:
source="genugate" AND (event_type="authentication" AND result="success") AND (user="root" OR user="admin") AND src_ip NOT IN trusted_networks🔗 References
- https://kunde.genua.de/en/overview/genugate.html
- https://sec-consult.com/vulnerability-lab/advisory/authentication-bypass-genua-genugate/
- https://www.genua.de/en/it-security-solutions/high-resistance-firewall-genugate
- https://kunde.genua.de/en/overview/genugate.html
- https://sec-consult.com/vulnerability-lab/advisory/authentication-bypass-genua-genugate/
- https://www.genua.de/en/it-security-solutions/high-resistance-firewall-genugate
