CVE-2024-21431
📋 TL;DR
This vulnerability allows attackers to bypass Hypervisor-Protected Code Integrity (HVCI) security features on Windows systems, potentially enabling them to execute malicious code with kernel privileges. It affects Windows 10, Windows 11, and Windows Server systems with HVCI enabled. Attackers need local access to exploit this vulnerability.
💻 Affected Systems
- Windows 10
- Windows 11
- Windows Server 2016
- Windows Server 2019
- Windows Server 2022
📦 What is this software?
Windows 10 21h2 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 21h2 by Microsoft
Windows 11 21h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 23h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain kernel-level code execution, allowing complete system compromise, persistence mechanisms, and disabling of security features.
Likely Case
Privilege escalation from user to kernel mode, enabling installation of rootkits, credential theft, and evasion of security monitoring.
If Mitigated
Limited impact with proper access controls, application allowlisting, and network segmentation in place.
🎯 Exploit Status
Requires local access and HVCI to be enabled. Exploitation requires sophisticated knowledge of Windows kernel internals.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: March 2024 security updates (KB5035853 for Windows 11, KB5035849 for Windows 10, etc.)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21431
Restart Required: Yes
Instructions:
1. Apply March 2024 Windows security updates via Windows Update. 2. For enterprise environments, deploy updates through WSUS or Microsoft Endpoint Configuration Manager. 3. Restart systems after update installation.
🔧 Temporary Workarounds
Disable HVCI
windowsTemporarily disable Hypervisor-Protected Code Integrity to mitigate the vulnerability
reg add "HKLM\SYSTEM\CurrentControlSet\Control\DeviceGuard\Scenarios\HypervisorEnforcedCodeIntegrity" /v "Enabled" /t REG_DWORD /d 0 /f
Restart required
🧯 If You Can't Patch
- Implement strict access controls to limit local administrative access
- Deploy application control policies to restrict unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check if HVCI is enabled via PowerShell: Get-CimInstance -ClassName Win32_DeviceGuard -Namespace root\Microsoft\Windows\DeviceGuardCheck Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify March 2024 security updates are installed: wmic qfe list | findstr "KB5035853 KB5035849"📡 Detection & Monitoring
Log Indicators:
- Event ID 12 from Microsoft-Windows-CodeIntegrity/Operational logs
- Unexpected kernel-mode driver loads
- HVCI policy modification events
Network Indicators:
- Unusual outbound connections from systems with HVCI enabled
- Lateral movement attempts from compromised HVCI systems
SIEM Query:
EventID=12 AND SourceName="Microsoft-Windows-CodeIntegrity" AND EventData contains "HVCI"