CVE-2021-30939
📋 TL;DR
This vulnerability allows attackers to execute arbitrary code by tricking users into processing maliciously crafted images. It affects Apple devices running outdated macOS, iOS, iPadOS, tvOS, and watchOS versions. Successful exploitation could give attackers full control of affected devices.
💻 Affected Systems
- macOS
- 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 →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 system compromise leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Malware installation through malicious images in messages, emails, or websites, potentially leading to credential theft or surveillance.
If Mitigated
Limited impact if devices are patched, images are processed in sandboxed environments, or user interaction is required.
🎯 Exploit Status
Exploitation requires user interaction to process malicious images. No public exploit code is known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.6.2, macOS Monterey 12.1, Security Update 2021-008 Catalina, iOS 15.2, iPadOS 15.2, tvOS 15.2, watchOS 8.3
Vendor Advisory: https://support.apple.com/en-us/HT212975
Restart Required: Yes
Instructions:
1. Go to Settings > General > Software Update on iOS/iPadOS/watchOS/tvOS. 2. On macOS, go to System Preferences > Software Update. 3. Install the latest available update. 4. Restart the device when prompted.
🔧 Temporary Workarounds
Disable automatic image processing
allConfigure email clients and browsers to not automatically download or process images from untrusted sources.
Use application sandboxing
macOSEnsure image processing applications run in sandboxed environments where possible.
🧯 If You Can't Patch
- Restrict image file processing from untrusted sources
- Implement network segmentation to isolate vulnerable devices
🔍 How to Verify
Check if Vulnerable:
Check system version against affected versions list. On macOS: System Information > Software > System Version. On iOS/iPadOS: Settings > General > About > Version.Check Version:
macOS: sw_vers -productVersion; iOS/iPadOS: Settings > General > About > Version (no command line)Verify Fix Applied:
Verify system version matches or exceeds patched versions listed in fix_official.patch_version.📡 Detection & Monitoring
Log Indicators:
- Unexpected process crashes in image processing applications
- Suspicious file access patterns to image files
Network Indicators:
- Unusual outbound connections from image processing applications
- Downloads of suspicious image files
SIEM Query:
Process: (name: Preview OR name: Photos OR name: Safari) AND EventID: 1000 (Application Crash)🔗 References
- https://support.apple.com/en-us/HT212975
- https://support.apple.com/en-us/HT212976
- https://support.apple.com/en-us/HT212978
- https://support.apple.com/en-us/HT212979
- https://support.apple.com/en-us/HT212980
- https://support.apple.com/en-us/HT212981
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1414
- https://www.zerodayinitiative.com/advisories/ZDI-22-359/
- https://support.apple.com/en-us/HT212975
- https://support.apple.com/en-us/HT212976
- https://support.apple.com/en-us/HT212978
- https://support.apple.com/en-us/HT212979
- https://support.apple.com/en-us/HT212980
- https://support.apple.com/en-us/HT212981
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1414
- https://www.zerodayinitiative.com/advisories/ZDI-22-359/
