CVE-2020-29624
📋 TL;DR
This memory corruption vulnerability in Apple's font processing allows attackers to execute arbitrary code by tricking users into opening malicious font files. It affects multiple Apple operating systems including macOS, iOS, iPadOS, watchOS, and tvOS. Users who process untrusted font files are at risk of complete system compromise.
💻 Affected Systems
- macOS
- iOS
- iPadOS
- watchOS
- tvOS
📦 What is this software?
Ipados by Apple
Macos by Apple
macOS is Apple's desktop and laptop operating system powering Mac computers used by millions of professionals, developers, creative professionals, and enterprise users worldwide. Built on a Unix foundation with the Darwin kernel and modern Cocoa frameworks, macOS delivers a seamless ecosystem integr...
Learn more about Macos →Tvos by Apple
Watchos by Apple
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining root privileges and persistent access to the device.
Likely Case
Malicious font file delivered via phishing or compromised website leads to malware installation and data theft.
If Mitigated
With proper patching and security controls, impact is limited to isolated application crashes.
🎯 Exploit Status
Exploitation requires user to open malicious font file; no known public exploits but memory corruption vulnerabilities are often weaponized.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: watchOS 7.2, macOS Big Sur 11.1, Security Update 2020-001 Catalina, Security Update 2020-007 Mojave, iOS 14.3, iPadOS 14.3, tvOS 14.3
Vendor Advisory: https://support.apple.com/en-us/HT212003
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available updates. 3. Restart device when prompted. For enterprise: Deploy updates via MDM or Apple Business/School Manager.
🔧 Temporary Workarounds
Restrict Font Installation
macOSPrevent installation of new font files via system policies.
sudo chmod 000 /Library/Fonts
sudo chmod 000 ~/Library/Fonts
Block Font Files at Perimeter
allFilter .ttf, .otf, .dfont files at email gateways and web proxies.
🧯 If You Can't Patch
- Implement application whitelisting to prevent unauthorized font processing applications
- Deploy endpoint detection and response (EDR) to monitor for suspicious font file activity
🔍 How to Verify
Check if Vulnerable:
Check system version: macOS - About This Mac > Overview; iOS/iPadOS - Settings > General > About; watchOS - Watch app > General > About; tvOS - Settings > General > AboutCheck Version:
macOS: sw_vers -productVersion; iOS/iPadOS: Settings > General > About > VersionVerify Fix Applied:
Verify installed version matches or exceeds patched versions listed in fix_official.patch_version📡 Detection & Monitoring
Log Indicators:
- Unexpected font file processing in system logs
- Application crashes related to font loading
Network Indicators:
- Downloads of font files from untrusted sources
- Font file attachments in email traffic
SIEM Query:
process_name:"fontd" AND (event_type:"crash" OR parent_process:"Safari" OR parent_process:"Mail")🔗 References
- https://support.apple.com/en-us/HT212003
- https://support.apple.com/en-us/HT212005
- https://support.apple.com/en-us/HT212009
- https://support.apple.com/en-us/HT212011
- https://support.apple.com/en-us/HT212003
- https://support.apple.com/en-us/HT212005
- https://support.apple.com/en-us/HT212009
- https://support.apple.com/en-us/HT212011
