CVE-2021-1744
📋 TL;DR
This vulnerability allows arbitrary code execution through malicious image processing. An attacker can craft a malicious image that triggers an out-of-bounds write when processed by affected Apple operating systems. Users of macOS, iOS, iPadOS, watchOS, and tvOS are affected.
💻 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
Complete system compromise with kernel-level privileges leading to data theft, persistence, and lateral movement.
Likely Case
Malicious app or website delivers crafted image that executes code with user privileges, potentially stealing data or installing malware.
If Mitigated
With proper network segmentation and least privilege, impact limited to isolated user session without administrative access.
🎯 Exploit Status
Exploitation requires user to process malicious image but no authentication needed. Apple has patched this vulnerability.
🛠️ 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. Open System Preferences > Software Update. 2. Install available updates. 3. Restart device when prompted.
🔧 Temporary Workarounds
Disable automatic image processing
allPrevent automatic image loading in browsers and email clients
🧯 If You Can't Patch
- Implement application allowlisting to prevent unauthorized code execution
- Use network segmentation to isolate vulnerable systems from critical assets
🔍 How to Verify
Check if Vulnerable:
Check system version against affected versions list. On macOS: About This Mac > Overview.Check Version:
macOS: sw_vers -productVersion; iOS/iPadOS: Settings > General > About > VersionVerify 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 services
- Memory access violations in system logs
Network Indicators:
- Unusual outbound connections from image processing applications
- Downloads of suspicious image files
SIEM Query:
Process creation events from image viewers/editors followed by network connections or file writes🔗 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
