CVE-2021-30760
📋 TL;DR
An integer overflow vulnerability in Apple's font processing allows arbitrary code execution when processing malicious font files. This affects iOS, macOS, watchOS, and tvOS devices. Attackers can exploit this by tricking users into opening malicious documents or visiting compromised websites.
💻 Affected Systems
- iOS
- macOS
- 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
Remote code execution leading to data theft, ransomware deployment, or device takeover.
If Mitigated
Limited impact with proper network segmentation and application sandboxing, though code execution still possible.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious document or visiting malicious website). No public exploit code available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: iOS 14.7, macOS Big Sur 11.5, watchOS 7.6, tvOS 14.7, Security Update 2021-005 Mojave, Security Update 2021-004 Catalina
Vendor Advisory: https://support.apple.com/en-us/HT212600
Restart Required: Yes
Instructions:
1. Open Settings/System Preferences. 2. Navigate to Software Update. 3. Install available updates. 4. Restart device when prompted.
🔧 Temporary Workarounds
Disable automatic font installation
macosPrevent automatic processing of embedded fonts in documents
Use application sandboxing
allEnsure applications processing fonts run in sandboxed environments
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable devices
- Deploy application whitelisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check system version against affected versions listCheck Version:
macOS: sw_vers -productVersion, iOS: Settings > General > About > VersionVerify Fix Applied:
Verify system version is equal to or greater than patched versions📡 Detection & Monitoring
Log Indicators:
- Unexpected font file processing
- Application crashes in font-related processes
Network Indicators:
- Downloads of font files from untrusted sources
- Font file transfers in unexpected protocols
SIEM Query:
process_name:fontd AND (event_type:crash OR parent_process:web_browser)🔗 References
- https://support.apple.com/en-us/HT212600
- https://support.apple.com/en-us/HT212601
- https://support.apple.com/en-us/HT212602
- https://support.apple.com/en-us/HT212603
- https://support.apple.com/en-us/HT212604
- https://support.apple.com/en-us/HT212605
- https://support.apple.com/en-us/HT212600
- https://support.apple.com/en-us/HT212601
- https://support.apple.com/en-us/HT212602
- https://support.apple.com/en-us/HT212603
- https://support.apple.com/en-us/HT212604
- https://support.apple.com/en-us/HT212605
