CVE-2020-27942
📋 TL;DR
This vulnerability allows arbitrary code execution by processing a maliciously crafted font file on affected macOS systems. It affects macOS Catalina and Mojave users who open malicious font files, potentially giving attackers full system control.
💻 Affected Systems
- macOS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining root privileges and persistent access to the device.
Likely Case
Local privilege escalation or remote code execution when user opens a malicious font file.
If Mitigated
Limited impact with proper application sandboxing and user awareness preventing font file execution.
🎯 Exploit Status
Requires user interaction to open malicious font file. No public exploit code available as of analysis.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Security Update 2021-002 for Catalina, Security Update 2021-003 for Mojave
Vendor Advisory: https://support.apple.com/en-us/HT212326
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install Security Update 2021-002 (Catalina) or 2021-003 (Mojave). 3. Restart computer when prompted.
🔧 Temporary Workarounds
Disable automatic font installation
allPrevent automatic processing of font files from untrusted sources
User education on font files
allTrain users to avoid opening font files from unknown sources
🧯 If You Can't Patch
- Restrict user permissions to prevent font file execution
- Implement application whitelisting to block suspicious font processing
🔍 How to Verify
Check if Vulnerable:
Check macOS version: Catalina 10.15.7 or earlier, Mojave 10.14.6 or earlierCheck Version:
sw_versVerify Fix Applied:
Verify Security Update 2021-002 (Catalina) or 2021-003 (Mojave) is installed via System Preferences > Software Update📡 Detection & Monitoring
Log Indicators:
- Unusual font file processing in system logs
- Crash reports from font-related processes
Network Indicators:
- Downloads of font files from suspicious sources
SIEM Query:
process_name:fontd AND (parent_process:user_interactive OR file_path:*.ttf OR file_path:*.otf)