CVE-2021-24102
📋 TL;DR
CVE-2021-24102 is a Windows Event Tracing elevation of privilege vulnerability that allows authenticated attackers to execute arbitrary code with SYSTEM privileges. This affects Windows systems where an attacker has local access and can exploit improper handling of objects in memory. The vulnerability enables privilege escalation from a lower-privileged account to SYSTEM-level access.
💻 Affected Systems
- Microsoft Windows
📦 What is this software?
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 7 by Microsoft
Windows 8.1 by Microsoft
Windows Rt 8.1 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM privileges, enabling installation of persistent malware, credential theft, lateral movement, and data exfiltration.
Likely Case
Local privilege escalation allowing attackers to bypass security controls, install additional malware, or access restricted system resources.
If Mitigated
Limited impact due to proper access controls, network segmentation, and endpoint protection preventing successful exploitation.
🎯 Exploit Status
Exploitation requires local authenticated access and knowledge of Windows internals; proof-of-concept code has been published.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: March 2021 security updates (KB5000802 for most versions)
Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-24102
Restart Required: Yes
Instructions:
1. Apply March 2021 Windows security updates via Windows Update. 2. For enterprise environments, deploy through WSUS or SCCM. 3. Verify update installation with 'wmic qfe list' or 'systeminfo' command.
🔧 Temporary Workarounds
Restrict local user privileges
windowsLimit local user accounts to standard user privileges to reduce attack surface.
Enable Windows Defender Exploit Guard
windowsConfigure Exploit Guard to detect and block privilege escalation attempts.
🧯 If You Can't Patch
- Implement strict access controls and least privilege principles for all user accounts.
- Deploy endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts.
🔍 How to Verify
Check if Vulnerable:
Check Windows version and installed updates; systems without March 2021 security updates are vulnerable.Check Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify KB5000802 or appropriate March 2021 security update is installed using 'wmic qfe list | findstr KB5000802' or check Windows Update history.📡 Detection & Monitoring
Log Indicators:
- Windows Security Event ID 4688 (process creation) showing unusual SYSTEM privilege processes from user accounts
- Event Tracing for Windows (ETW) related errors or unusual activity
Network Indicators:
- Unusual outbound connections from SYSTEM processes
- Lateral movement attempts following privilege escalation
SIEM Query:
EventID=4688 AND NewProcessName CONTAINS "cmd.exe" OR "powershell.exe" AND SubjectUserName NOT IN ("SYSTEM", "LOCAL SERVICE", "NETWORK SERVICE") AND TokenElevationType="%%1938"