CVE-2021-27792
📋 TL;DR
This vulnerability in Brocade Fabric OS web management interface allows authenticated attackers to crash the HTTP application handler by sending malformed input, requiring a system reboot to restore service. It affects Brocade Fabric OS versions before v9.0.1a, v8.2.3a, and v7.4.2h. Only authenticated users can exploit this weakness.
💻 Affected Systems
- Brocade Fabric OS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Denial of service causing complete unavailability of the web management interface, requiring physical or console access to reboot the affected device, potentially disrupting storage network operations.
Likely Case
Temporary service disruption of the web management interface requiring administrative intervention to reboot the affected device, causing management inconvenience but not affecting data plane operations.
If Mitigated
Minimal impact with proper network segmentation and access controls limiting authenticated access to trusted administrators only.
🎯 Exploit Status
Exploitation requires authenticated access to the web management interface. No public exploit code identified in references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v9.0.1a, v8.2.3a, v7.4.2h or later
Vendor Advisory: https://www.broadcom.com/support/fibre-channel-networking/security-advisories/brocade-security-advisory-2021-1490
Restart Required: Yes
Instructions:
1. Download appropriate firmware update from Broadcom support portal. 2. Backup current configuration. 3. Apply firmware update following vendor documentation. 4. Reboot device to complete installation. 5. Verify version after reboot.
🔧 Temporary Workarounds
Disable Web Management Interface
allTemporarily disable the vulnerable web interface component
firmwareshow
ipaddrset --disable
or consult vendor documentation for specific disable commands
Restrict Network Access
allLimit access to web management interface using firewall rules
Configure firewall to allow only trusted management IPs to access web interface ports (typically 80/443)
🧯 If You Can't Patch
- Implement strict access controls limiting web interface access to essential administrators only
- Monitor for abnormal web interface crashes and implement alerting for reboot events
🔍 How to Verify
Check if Vulnerable:
Check Fabric OS version using 'version' command and compare against patched versionsCheck Version:
versionVerify Fix Applied:
After patching, verify version shows v9.0.1a, v8.2.3a, v7.4.2h or later using 'version' command📡 Detection & Monitoring
Log Indicators:
- Unexpected web service crashes
- HTTP application handler restart events
- System reboot logs without administrative action
Network Indicators:
- Multiple malformed HTTP requests to management interface from single source
- Sudden loss of web interface connectivity
SIEM Query:
source="brocade_logs" AND (event="service_crash" OR event="reboot") AND process="http_handler"🔗 References
- https://security.netapp.com/advisory/ntap-20210819-0002/
- https://www.broadcom.com/support/fibre-channel-networking/security-advisories/brocade-security-advisory-2021-1490
- https://www.broadcom.com/support/fibre-channel-networking/security-advisories/brocade-security-advisory-2021-1492
- https://security.netapp.com/advisory/ntap-20210819-0002/
- https://www.broadcom.com/support/fibre-channel-networking/security-advisories/brocade-security-advisory-2021-1490
- https://www.broadcom.com/support/fibre-channel-networking/security-advisories/brocade-security-advisory-2021-1492
