CVE-2021-41021
📋 TL;DR
This CVE describes a privilege escalation vulnerability in FortiNAC where an authenticated admin user can elevate privileges to root via sudo command misconfiguration. Affected organizations are those running FortiNAC versions 8.8.8 and below or 9.1.2 and below.
💻 Affected Systems
- FortiNAC
📦 What is this software?
Fortinac by Fortinet
Fortinac by Fortinet
Fortinac by Fortinet
Fortinac by Fortinet
Fortinac by Fortinet
Fortinac by Fortinet
Fortinac by Fortinet
Fortinac by Fortinet
Fortinac by Fortinet
Fortinac by Fortinet
Fortinac by Fortinet
Fortinac by Fortinet
⚠️ Risk & Real-World Impact
Worst Case
An authenticated admin user gains full root access to the FortiNAC system, allowing complete system compromise, data theft, and lateral movement within the network.
Likely Case
Malicious insider or compromised admin account escalates to root, enabling persistence, credential harvesting, and network reconnaissance.
If Mitigated
With proper access controls and monitoring, impact is limited to alerting on suspicious privilege escalation attempts.
🎯 Exploit Status
Exploitation requires admin credentials and knowledge of sudo misconfiguration. No public exploit code available at time of analysis.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 8.8.9 and 9.1.3
Vendor Advisory: https://fortiguard.com/advisory/FG-IR-21-182
Restart Required: Yes
Instructions:
1. Backup FortiNAC configuration. 2. Upgrade to FortiNAC version 8.8.9 or 9.1.3 or later. 3. Verify sudo configuration changes. 4. Restart services as required.
🔧 Temporary Workarounds
Restrict sudo access
linuxReview and restrict sudo permissions for admin users to prevent privilege escalation.
sudo visudo
# Review and remove unnecessary sudo permissions for admin users
Implement least privilege
allApply principle of least privilege to admin accounts and monitor sudo usage.
🧯 If You Can't Patch
- Implement strict access controls and monitoring for admin accounts
- Regularly audit sudo configurations and admin user activities
🔍 How to Verify
Check if Vulnerable:
Check FortiNAC version via web interface or CLI. If version is 8.8.8 or below, or 9.1.2 or below, system is vulnerable.Check Version:
From FortiNAC CLI: show versionVerify Fix Applied:
Verify FortiNAC version is 8.8.9 or 9.1.3 or later, and review sudo configuration for proper restrictions.📡 Detection & Monitoring
Log Indicators:
- Unexpected sudo usage by admin users
- Root privilege escalation attempts
- Authentication logs showing admin access followed by sudo commands
Network Indicators:
- Unusual administrative traffic patterns
- Changes to sudo configuration files
SIEM Query:
source="fortinac" AND (event_type="sudo" OR event_type="privilege_escalation") AND user="admin"