CVE-2021-40996
📋 TL;DR
A remote authentication bypass vulnerability in Aruba ClearPass Policy Manager allows attackers to bypass authentication mechanisms and gain unauthorized access to the system. This affects ClearPass Policy Manager versions 6.8.x prior to 6.8.9-HF1, 6.9.x prior to 6.9.7-HF1, and 6.10.x prior to 6.10.2.
💻 Affected Systems
- Aruba ClearPass Policy Manager
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the ClearPass Policy Manager system, allowing attackers to gain administrative access, modify network policies, steal sensitive authentication data, and pivot to other network resources.
Likely Case
Unauthorized access to the ClearPass management interface, enabling attackers to view or modify network access policies, user credentials, and device configurations.
If Mitigated
Limited impact if system is isolated, has strict network access controls, and monitoring detects authentication anomalies.
🎯 Exploit Status
The vulnerability allows remote authentication bypass, suggesting relatively straightforward exploitation once details are known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.8.9-HF1, 6.9.7-HF1, or 6.10.2 depending on current version
Vendor Advisory: https://www.arubanetworks.com/assets/alert/ARUBA-PSA-2021-018.txt
Restart Required: Yes
Instructions:
1. Download appropriate patch from Aruba support portal. 2. Backup current configuration. 3. Apply patch following Aruba's upgrade procedures. 4. Restart ClearPass services. 5. Verify system functionality.
🔧 Temporary Workarounds
Network Isolation
allRestrict network access to ClearPass Policy Manager to only trusted management networks
Configure firewall rules to limit inbound access to ClearPass management interface
🧯 If You Can't Patch
- Implement strict network segmentation to isolate ClearPass from untrusted networks
- Enable detailed authentication logging and monitor for suspicious authentication attempts
🔍 How to Verify
Check if Vulnerable:
Check ClearPass version via web interface or CLI. If version is 6.8.x < 6.8.9-HF1, 6.9.x < 6.9.7-HF1, or 6.10.x < 6.10.2, system is vulnerable.Check Version:
From CLI: show version or check via web interface at Administration > Support > System InformationVerify Fix Applied:
Verify version is updated to 6.8.9-HF1, 6.9.7-HF1, or 6.10.2 or later. Test authentication mechanisms work properly.📡 Detection & Monitoring
Log Indicators:
- Failed authentication attempts followed by successful access from same source
- Authentication logs showing bypass patterns
- Unusual administrative access from unexpected IP addresses
Network Indicators:
- Unusual authentication traffic patterns to ClearPass management interface
- Traffic from unexpected sources to authentication endpoints
SIEM Query:
source="clearpass" AND (event_type="authentication" OR event_type="admin_access") AND result="success" AND src_ip NOT IN [trusted_management_ips]