CVE-2021-1742
📋 TL;DR
CVE-2021-1742 is a memory corruption vulnerability in Apple's image processing that allows arbitrary code execution when processing a maliciously crafted image. It affects multiple Apple operating systems including macOS, iOS, iPadOS, watchOS, and tvOS. Attackers can exploit this by tricking users into opening malicious image files.
💻 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
Malware installation, data theft, or device takeover when user opens malicious image from untrusted source.
If Mitigated
Limited impact with proper patch management and user education about opening untrusted files.
🎯 Exploit Status
Exploitation requires user interaction to open malicious image. No public exploit code is known, but Apple addressed it as a serious memory corruption issue.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, watchOS 7.3, tvOS 14.4, iOS 14.4, iPadOS 14.4
Vendor Advisory: https://support.apple.com/en-us/HT212146
Restart Required: Yes
Instructions:
1. Go to System Preferences > Software Update. 2. Install available updates. 3. Restart device when prompted. For iOS/iPadOS: Settings > General > Software Update.
🔧 Temporary Workarounds
Restrict image file handling
allConfigure applications to open images in sandboxed viewers or disable automatic image processing
User education
allTrain users to avoid opening image files from untrusted sources
🧯 If You Can't Patch
- Implement application whitelisting to prevent unauthorized applications from processing images
- Use network filtering to block suspicious image downloads and implement email filtering for malicious attachments
🔍 How to Verify
Check if Vulnerable:
Check current OS version against affected versions listed in Apple advisoriesCheck Version:
macOS: sw_vers -productVersion; iOS/iPadOS: Settings > General > About > Version; watchOS: Watch app > General > About > Version; tvOS: Settings > General > About > VersionVerify Fix Applied:
Verify OS version is equal to or newer than patched versions listed in affected_systems.versions📡 Detection & Monitoring
Log Indicators:
- Unexpected application crashes when processing images
- Memory access violation logs in system logs
Network Indicators:
- Unusual outbound connections after image file processing
- Downloads of suspicious image files from untrusted sources
SIEM Query:
Image:*.crash OR Process:memory_violation AND Application:image_processor OR File:*.jpg|*.png|*.gif AND Event:malicious_activity🔗 References
- https://support.apple.com/en-us/HT212146
- https://support.apple.com/en-us/HT212147
- https://support.apple.com/en-us/HT212148
- https://support.apple.com/en-us/HT212149
- https://support.apple.com/en-us/HT212146
- https://support.apple.com/en-us/HT212147
- https://support.apple.com/en-us/HT212148
- https://support.apple.com/en-us/HT212149
