CVE-2021-3969
📋 TL;DR
A local privilege escalation vulnerability exists in Lenovo System Interface Foundation's IMController component due to a Time-of-Check Time-of-Use (TOCTOU) race condition. This allows a local attacker with standard user privileges to execute arbitrary code with SYSTEM/root privileges. Only systems running vulnerable versions of Lenovo System Interface Foundation are affected.
💻 Affected Systems
- Lenovo System Interface Foundation
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise where an attacker gains full administrative control, can install malware, steal credentials, and persist across reboots.
Likely Case
Local attacker elevates privileges to install additional malware, disable security controls, or access protected system resources.
If Mitigated
Attack fails due to patched software or restricted local access preventing exploitation.
🎯 Exploit Status
Requires local access and ability to execute code. TOCTOU vulnerabilities typically require precise timing but can be reliably exploited.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.1.20.3 or later
Vendor Advisory: https://support.lenovo.com/us/en/product_security/LEN-75210
Restart Required: Yes
Instructions:
1. Download Lenovo System Interface Foundation version 1.1.20.3 or later from Lenovo's support site. 2. Run the installer with administrative privileges. 3. Restart the system when prompted.
🔧 Temporary Workarounds
Uninstall Lenovo System Interface Foundation
windowsRemove the vulnerable component entirely if not required for system functionality.
Control Panel > Programs > Uninstall a program > Select 'Lenovo System Interface Foundation' > Uninstall
Restrict local user privileges
windowsLimit standard users' ability to execute arbitrary code through application control policies.
🧯 If You Can't Patch
- Implement strict application control policies to prevent unauthorized code execution
- Segment networks to limit lateral movement if local privilege escalation occurs
🔍 How to Verify
Check if Vulnerable:
Check installed version of Lenovo System Interface Foundation in Control Panel > Programs > Programs and Features. If version is earlier than 1.1.20.3, system is vulnerable.Check Version:
wmic product where name='Lenovo System Interface Foundation' get versionVerify Fix Applied:
Verify Lenovo System Interface Foundation version is 1.1.20.3 or later in Control Panel > Programs > Programs and Features.📡 Detection & Monitoring
Log Indicators:
- Unusual process creation from IMController.exe
- Suspicious privilege escalation attempts in Windows Security logs
Network Indicators:
- None - this is a local privilege escalation
SIEM Query:
EventID=4688 AND ProcessName='IMController.exe' AND NewProcessName contains 'cmd.exe' OR 'powershell.exe'