CVE-2020-16902
📋 TL;DR
This Windows Installer vulnerability allows a local attacker to execute arbitrary code with SYSTEM privileges by exploiting improper input sanitization. It affects Windows systems where an authenticated user can run malicious installer packages. The attacker gains full control over the system.
💻 Affected Systems
- Windows Installer
📦 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 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 attacker gaining SYSTEM privileges, installing persistent malware, stealing all data, and creating backdoor accounts.
Likely Case
Privilege escalation from standard user to SYSTEM, enabling installation of unauthorized software, data theft, and lateral movement.
If Mitigated
Limited impact if proper patch management and least privilege principles are enforced, though local authenticated users could still attempt exploitation.
🎯 Exploit Status
Requires local authenticated access and specific conditions to trigger the insecure library loading; not trivial but achievable by determined attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: October 2020 security updates (KB4579311, KB4577671, etc. depending on Windows version)
Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16902
Restart Required: Yes
Instructions:
1. Apply October 2020 Windows security updates via Windows Update. 2. For enterprise environments, deploy through WSUS or SCCM. 3. Restart systems after patch installation.
🔧 Temporary Workarounds
Restrict installer execution
windowsLimit who can execute Windows Installer packages through Group Policy or application control policies
Implement least privilege
windowsEnsure users operate with minimal necessary privileges to reduce impact if exploited
🧯 If You Can't Patch
- Implement strict application control policies to block unauthorized installer execution
- Monitor for suspicious installer activity and privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check if October 2020 security updates are installed via 'wmic qfe list' or 'systeminfo' commandCheck Version:
wmic qfe list | findstr KB4579311 or systeminfo | findstr "Hotfix"Verify Fix Applied:
Verify KB4579311 (or relevant KB for your Windows version) is installed and system has been restarted📡 Detection & Monitoring
Log Indicators:
- Windows Installer logs showing unexpected package execution
- Security logs showing privilege escalation events
- Process creation logs showing SYSTEM privilege acquisition
Network Indicators:
- Not network exploitable; focus on host-based indicators
SIEM Query:
EventID=4688 AND NewProcessName="*installer*" AND SubjectUserName!=SYSTEM AND TokenElevationType=%%1938