CVE-2021-1651
📋 TL;DR
This vulnerability allows a local attacker to execute arbitrary code with SYSTEM privileges on Windows systems. It affects Windows 10, Windows Server 2016, and later versions where Diagnostics Hub Standard Collector is present. Attackers can exploit this to gain complete control over affected systems.
💻 Affected Systems
- Windows 10
- Windows Server 2016
- Windows Server 2019
- Windows Server 2022
📦 What is this software?
Visual Studio 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
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM privileges, enabling installation of malware, data theft, and lateral movement across the network.
Likely Case
Local privilege escalation allowing attackers to bypass security controls, install persistent backdoors, and access sensitive system resources.
If Mitigated
Limited impact if proper endpoint protection and least privilege principles are enforced, though local attackers could still gain elevated access.
🎯 Exploit Status
Exploitation requires local access to the system. Public proof-of-concept code exists, making exploitation straightforward for attackers with local access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: January 2021 security updates (KB4598242 for Windows 10 2004/20H2, KB4598230 for Windows 10 1909, etc.)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1651
Restart Required: Yes
Instructions:
1. Apply the January 2021 Windows security updates from Microsoft Update. 2. For enterprise environments, deploy updates through WSUS or SCCM. 3. Restart systems after patch installation.
🔧 Temporary Workarounds
Disable Diagnostics Hub Standard Collector Service
windowsDisables the vulnerable service to prevent exploitation
sc config diagtrack start= disabled
sc stop diagtrack
Remove Diagnostics Hub Standard Collector
windowsUninstalls the vulnerable component completely
DISM /Online /Remove-Capability /CapabilityName:Microsoft.Windows.DiagnosticHub.StandardCollector~~~~0.0.1.0
🧯 If You Can't Patch
- Implement strict least privilege access controls to limit local user privileges
- Deploy endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check if the system has Diagnostics Hub Standard Collector installed and if January 2021 security updates are not appliedCheck Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify that January 2021 security updates are installed and the system version is patched📡 Detection & Monitoring
Log Indicators:
- Event ID 4688 with parent process name containing 'diagtrack' or 'DiagnosticsHub'
- Unexpected SYSTEM privilege escalation from user accounts
Network Indicators:
- Unusual outbound connections from systems after local privilege escalation
SIEM Query:
EventID=4688 AND (ParentProcessName LIKE '%diagtrack%' OR ParentProcessName LIKE '%DiagnosticsHub%')