CVE-2021-28310
📋 TL;DR
CVE-2021-28310 is a Win32k elevation of privilege vulnerability in Windows kernel-mode drivers. It allows authenticated attackers to execute arbitrary code with SYSTEM privileges, affecting Windows 10, Windows Server 2016, and later versions. This vulnerability requires an attacker to have local access to the target system.
💻 Affected Systems
- Windows 10
- Windows Server 2016
- Windows Server 2019
- Windows Server 2022
📦 What is this software?
Windows 10 1803 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 1909 by Microsoft
Windows 10 2004 by Microsoft
Windows 10 20h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise where an attacker gains SYSTEM privileges, installs persistent malware, steals credentials, and disables security controls.
Likely Case
Privilege escalation from a standard user account to SYSTEM privileges, enabling lateral movement, credential dumping, and persistence establishment.
If Mitigated
Limited impact with proper endpoint protection, least privilege enforcement, and network segmentation preventing lateral movement.
🎯 Exploit Status
Exploit requires authenticated access. Has been observed in active exploitation according to CISA's Known Exploited Vulnerabilities catalog.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Security updates from April 2021 or later
Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-28310
Restart Required: Yes
Instructions:
1. Apply Windows security updates from April 2021 or later. 2. For Windows 10, install KB5001330 or later. 3. For Windows Server 2016/2019/2022, install the corresponding security updates. 4. Restart the system after installation.
🔧 Temporary Workarounds
Restrict local administrator privileges
windowsImplement least privilege access controls to limit users who can run arbitrary code on systems.
Enable exploit protection
windowsUse Windows Defender Exploit Guard or similar solutions to mitigate exploitation attempts.
🧯 If You Can't Patch
- Implement strict network segmentation to limit lateral movement
- Deploy endpoint detection and response (EDR) solutions with behavioral monitoring
🔍 How to Verify
Check if Vulnerable:
Check if Windows security updates from April 2021 or later are installed. Systems without these updates are vulnerable.Check Version:
wmic qfe list | findstr KB5001330 (or relevant KB number)Verify Fix Applied:
Verify that KB5001330 (for Windows 10) or corresponding security updates for Server editions are installed.📡 Detection & Monitoring
Log Indicators:
- Unusual process creation with SYSTEM privileges
- Suspicious kernel-mode driver activity
- Event ID 4688 with elevated privileges
Network Indicators:
- Lateral movement attempts following local privilege escalation
- Abnormal authentication patterns from previously compromised systems
SIEM Query:
EventID=4688 AND NewProcessName="*" AND SubjectUserName!="SYSTEM" AND TokenElevationType="%%1938"