CVE-2021-30840
📋 TL;DR
This vulnerability allows arbitrary code execution by processing a maliciously crafted dfont file. It affects Apple devices running older versions of iOS, iPadOS, tvOS, and watchOS. Attackers could exploit this to run unauthorized code on vulnerable devices.
💻 Affected Systems
- iOS
- iPadOS
- tvOS
- watchOS
📦 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
Complete device compromise leading to data theft, surveillance, or ransomware deployment
Likely Case
Malware installation or data exfiltration when users open malicious dfont files
If Mitigated
No impact if devices are patched or if malicious files are blocked
🎯 Exploit Status
Exploitation requires user interaction to open malicious dfont file
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: iOS 15, iPadOS 15, tvOS 15, watchOS 8
Vendor Advisory: https://support.apple.com/en-us/HT212814
Restart Required: Yes
Instructions:
1. Open Settings app
2. Tap General
3. Tap Software Update
4. Install available update to iOS 15/iPadOS 15/tvOS 15/watchOS 8 or later
🔧 Temporary Workarounds
Block dfont file processing
allPrevent opening of dfont files through MDM or configuration profiles
🧯 If You Can't Patch
- Disable automatic font processing in apps
- Educate users not to open untrusted dfont files
🔍 How to Verify
Check if Vulnerable:
Check device version in Settings > General > About > Software VersionCheck Version:
Not applicable for Apple mobile devices (use Settings app)Verify Fix Applied:
Verify version is iOS 15/iPadOS 15/tvOS 15/watchOS 8 or later📡 Detection & Monitoring
Log Indicators:
- Unexpected font processing errors
- Crash reports from font-related processes
Network Indicators:
- Downloads of dfont files from untrusted sources
SIEM Query:
Not applicable for typical Apple device deployments🔗 References
- https://support.apple.com/en-us/HT212814
- https://support.apple.com/en-us/HT212815
- https://support.apple.com/en-us/HT212819
- https://support.apple.com/kb/HT212869
- https://support.apple.com/en-us/HT212814
- https://support.apple.com/en-us/HT212815
- https://support.apple.com/en-us/HT212819
- https://support.apple.com/kb/HT212869
