CVE-2021-26677
📋 TL;DR
This vulnerability allows local authenticated users on Windows systems running vulnerable Aruba ClearPass Policy Manager versions to escalate their privileges to SYSTEM level. Attackers could execute arbitrary code with full system control. Only affects ClearPass OnGuard components on Windows platforms.
💻 Affected Systems
- Aruba ClearPass Policy Manager
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM privileges, allowing installation of persistent malware, credential theft, lateral movement, and data exfiltration.
Likely Case
Local privilege escalation leading to administrative control over the ClearPass server, potentially compromising the entire network authentication infrastructure.
If Mitigated
Limited impact if proper network segmentation, least privilege access, and monitoring are in place to detect and contain local privilege escalation attempts.
🎯 Exploit Status
Requires local authenticated access to the Windows system. No public exploit code is known, but local privilege escalation vulnerabilities are often weaponized.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.9.5, 6.8.8-HF1, or 6.7.14-HF1
Vendor Advisory: https://www.arubanetworks.com/assets/alert/ARUBA-PSA-2021-004.txt
Restart Required: Yes
Instructions:
1. Backup ClearPass configuration and data. 2. Download appropriate patch version from Aruba support portal. 3. Apply patch following Aruba's upgrade documentation. 4. Restart ClearPass services. 5. Verify successful upgrade and functionality.
🔧 Temporary Workarounds
Restrict Local Access
windowsLimit local login access to ClearPass Windows servers to only necessary administrative accounts.
Use Windows Group Policy to restrict local logon rights
Remove non-essential users from local administrators group
Network Segmentation
allIsolate ClearPass servers in a protected network segment with strict access controls.
Configure firewall rules to limit access to ClearPass management interfaces
Implement network segmentation between user and management networks
🧯 If You Can't Patch
- Implement strict least privilege access controls for all user accounts on ClearPass servers
- Enable detailed auditing and monitoring for privilege escalation attempts and unusual process execution
🔍 How to Verify
Check if Vulnerable:
Check ClearPass version via web interface (Administration > Support > About) or command line: 'appliance version'Check Version:
appliance versionVerify Fix Applied:
Verify version is 6.9.5, 6.8.8-HF1, or 6.7.14-HF1 or later. Test OnGuard functionality remains operational.📡 Detection & Monitoring
Log Indicators:
- Windows Event Logs showing privilege escalation attempts
- ClearPass logs showing unusual OnGuard process behavior
- Security logs with unexpected SYSTEM privilege processes
Network Indicators:
- Unusual outbound connections from ClearPass server
- Anomalous authentication patterns from ClearPass
SIEM Query:
source="windows-security" EventCode=4672 AND SubjectUserName!="SYSTEM" AND PrivilegeList="SeDebugPrivilege" OR source="clearpass" message="*OnGuard*privilege*"