CVE-2021-1732
📋 TL;DR
CVE-2021-1732 is a privilege escalation vulnerability in the Windows Win32k kernel driver. It allows a local attacker to gain SYSTEM-level privileges by exploiting an offset confusion issue in the ConsoleControl function. This affects Windows systems where an attacker already has some level of local access.
💻 Affected Systems
- Microsoft Windows
📦 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 with SYSTEM privileges, enabling installation of malware, data theft, lateral movement, and persistence mechanisms.
Likely Case
Local privilege escalation from a lower-privileged user account to SYSTEM, allowing attackers to bypass security controls and execute arbitrary code.
If Mitigated
Limited impact if proper patch management and least privilege principles are enforced, though local attackers could still escalate within their access scope.
🎯 Exploit Status
Exploit requires local access and some technical knowledge. Multiple public proof-of-concept exploits exist.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: February 2021 security updates (KB4601319 for Windows 10 20H2, KB4601345 for Windows 10 2004, etc.)
Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1732
Restart Required: Yes
Instructions:
1. Apply the February 2021 Windows security updates from Windows Update. 2. For enterprise environments, deploy through WSUS or SCCM. 3. Restart systems after patch installation.
🔧 Temporary Workarounds
Restrict local access
windowsLimit local user access to systems through proper access controls and user privilege management.
🧯 If You Can't Patch
- Implement strict least privilege principles to limit damage from successful exploitation
- Monitor for suspicious local privilege escalation attempts and implement application whitelisting
🔍 How to Verify
Check if Vulnerable:
Check Windows version and if February 2021 security updates are installed via 'winver' command or System Information.Check Version:
winverVerify Fix Applied:
Verify KB4601319 (or relevant KB for your version) is installed in Installed Updates or via 'wmic qfe list' command.📡 Detection & Monitoring
Log Indicators:
- Event ID 4688 with suspicious parent processes
- Unexpected SYSTEM privilege acquisition by non-admin users
- Security log entries showing privilege escalation
Network Indicators:
- Not applicable - local exploit only
SIEM Query:
EventID=4688 AND NewProcessName LIKE '%cmd.exe%' OR '%powershell.exe%' AND SubjectUserName NOT IN (admin_users) AND TokenElevationType=%%1938🔗 References
- http://packetstormsecurity.com/files/161880/Win32k-ConsoleControl-Offset-Confusion.html
- http://packetstormsecurity.com/files/166169/Win32k-ConsoleControl-Offset-Confusion-Privilege-Escalation.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1732
- http://packetstormsecurity.com/files/161880/Win32k-ConsoleControl-Offset-Confusion.html
- http://packetstormsecurity.com/files/166169/Win32k-ConsoleControl-Offset-Confusion-Privilege-Escalation.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1732
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1732
