CVE-2021-23876
📋 TL;DR
This vulnerability allows a local user on a Windows system to bypass security controls in McAfee Total Protection, gaining SYSTEM-level privileges to modify files arbitrarily. Attackers could execute malware, cause denial of service, or perform other malicious actions with the highest system authority. Only users with local access to affected McAfee Total Protection installations are at risk.
💻 Affected Systems
- McAfee Total Protection (MTP)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise: attacker gains SYSTEM privileges, installs persistent malware, steals sensitive data, disables security controls, and causes permanent system damage.
Likely Case
Local privilege escalation leading to malware execution, file tampering, or disabling of security software for further attacks.
If Mitigated
Limited impact if proper endpoint security controls, least privilege principles, and network segmentation are implemented.
🎯 Exploit Status
Exploitation requires local access but is technically straightforward once access is obtained. The CWE-269 (Improper Privilege Management) suggests privilege escalation mechanisms are well-understood.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 16.0.30 or later
Vendor Advisory: http://service.mcafee.com/FAQDocument.aspx?&id=TS103114
Restart Required: Yes
Instructions:
1. Open McAfee Total Protection. 2. Navigate to Settings > General > Updates. 3. Click 'Check for Updates'. 4. Install all available updates. 5. Restart the computer when prompted.
🔧 Temporary Workarounds
Restrict Local User Privileges
windowsApply least privilege principles to limit what local users can do, reducing attack surface.
Enable Application Control
windowsUse application whitelisting to prevent unauthorized executables from running.
🧯 If You Can't Patch
- Implement strict endpoint detection and response (EDR) monitoring for privilege escalation attempts.
- Segment networks to limit lateral movement if local compromise occurs.
🔍 How to Verify
Check if Vulnerable:
Check McAfee Total Protection version: Open McAfee interface > Settings > About. If version is below 16.0.30, system is vulnerable.Check Version:
wmic product where "name like 'McAfee Total Protection%'" get versionVerify Fix Applied:
After updating, verify version is 16.0.30 or higher in Settings > About. Check Windows Event Logs for successful update installation.📡 Detection & Monitoring
Log Indicators:
- Unusual process creation with SYSTEM privileges from user contexts
- McAfee service manipulation events
- File modification in protected system directories
Network Indicators:
- None - this is a local privilege escalation vulnerability
SIEM Query:
EventID=4688 AND NewProcessName CONTAINS 'cmd.exe' OR 'powershell.exe' AND SubjectUserName NOT IN ('SYSTEM', 'LOCAL SERVICE', 'NETWORK SERVICE') AND TokenElevationType='%%1938'