CVE-2020-27938
📋 TL;DR
CVE-2020-27938 is a privilege escalation vulnerability in macOS that allows malicious applications to gain elevated system privileges. This affects macOS Catalina, Mojave, and Big Sur systems. Attackers could exploit this to bypass security restrictions and execute arbitrary code with higher privileges.
💻 Affected Systems
- macOS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise where an attacker gains root privileges, installs persistent malware, accesses sensitive data, and controls the entire system.
Likely Case
Local privilege escalation allowing malware to bypass sandbox restrictions, install additional payloads, or access protected system resources.
If Mitigated
Limited impact if proper application sandboxing and least privilege principles are enforced, though the vulnerability still provides a foothold for further exploitation.
🎯 Exploit Status
Requires user to execute malicious application. Apple has addressed this in security updates.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, macOS Big Sur 11.1, Security Update 2020-001 Catalina, Security Update 2020-007 Mojave
Vendor Advisory: https://support.apple.com/en-us/HT212011
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available security updates. 3. Restart the system when prompted.
🔧 Temporary Workarounds
Application Restriction
allRestrict execution of untrusted applications using Gatekeeper and application whitelisting
sudo spctl --master-enable
sudo spctl --enable --label "Developer ID"
🧯 If You Can't Patch
- Implement strict application control policies to prevent execution of untrusted applications
- Use endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check macOS version: if running Catalina, Mojave, or Big Sur without the security updates listed, system is vulnerableCheck Version:
sw_versVerify Fix Applied:
Verify macOS version is updated to patched versions: Big Sur 11.2+, Catalina with Security Update 2021-001+, Mojave with Security Update 2021-001+📡 Detection & Monitoring
Log Indicators:
- Unexpected privilege escalation events in system logs
- Suspicious application execution with elevated privileges
Network Indicators:
- Unusual outbound connections following local privilege escalation
SIEM Query:
source="macos_system_logs" AND (event="privilege_escalation" OR process="sudo" OR process="su") AND user!="authorized_user"