CVE-2020-27921
📋 TL;DR
This macOS kernel vulnerability allows a malicious application to exploit a race condition to execute arbitrary code with kernel privileges. It affects macOS Catalina, Mojave, and Big Sur systems. Successful exploitation gives attackers complete control over the affected system.
💻 Affected Systems
- macOS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with root-level persistence, data theft, and ability to disable security controls.
Likely Case
Malicious application gains kernel privileges to install malware, keyloggers, or backdoors.
If Mitigated
Limited impact if systems are patched and application execution is restricted to trusted sources.
🎯 Exploit Status
Race condition exploitation requires precise timing and kernel knowledge.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.1, Security Update 2020-001 Catalina, Security Update 2020-007 Mojave
Vendor Advisory: https://support.apple.com/en-us/HT211931
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available security updates. 3. Restart when prompted.
🔧 Temporary Workarounds
Restrict application execution
allOnly allow applications from identified developers or App Store
sudo spctl --master-enable
sudo spctl --enable
🧯 If You Can't Patch
- Restrict user privileges and application installation rights
- Implement application allowlisting and monitor for unauthorized software
🔍 How to Verify
Check if Vulnerable:
Check macOS version in System Preferences > About This MacCheck Version:
sw_versVerify Fix Applied:
Verify installed security update in System Preferences > Software Update > Installed Updates📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Unexpected privilege escalation in audit logs
Network Indicators:
- Unusual outbound connections from system processes
SIEM Query:
process where parent_process_name contains "kernel" and process_name not in approved_list