CVE-2021-1814
📋 TL;DR
A vulnerability in macOS and watchOS image processing allows arbitrary code execution when processing malicious images. Attackers can exploit this by tricking users into opening specially crafted image files. This affects macOS Big Sur before version 11.3 and watchOS before version 7.4.
💻 Affected Systems
- macOS
- watchOS
📦 What is this software?
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 →Watchos by Apple
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control over the affected device, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Local privilege escalation or remote code execution when user opens a malicious image file, leading to malware installation or data exfiltration.
If Mitigated
No impact if systems are fully patched or if users avoid opening untrusted image files from unknown sources.
🎯 Exploit Status
Exploitation requires user interaction (opening a malicious image file). No public exploit code has been disclosed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.3, watchOS 7.4
Vendor Advisory: https://support.apple.com/en-us/HT212324
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update on macOS or Watch app > General > Software Update on iPhone for watchOS. 2. Install macOS Big Sur 11.3 or watchOS 7.4 update. 3. Restart the device after installation completes.
🔧 Temporary Workarounds
Avoid untrusted image files
allDo not open image files from unknown or untrusted sources, especially via email attachments or downloads from suspicious websites.
🧯 If You Can't Patch
- Implement application whitelisting to prevent execution of unauthorized applications
- Use network segmentation to isolate vulnerable systems from critical assets
🔍 How to Verify
Check if Vulnerable:
Check macOS version: System Preferences > About This Mac. Check watchOS version: Watch app > General > About on paired iPhone.Check Version:
macOS: sw_vers -productVersion, watchOS: Not available via command line, check through Watch appVerify Fix Applied:
Verify macOS version is 11.3 or higher, watchOS version is 7.4 or higher.📡 Detection & Monitoring
Log Indicators:
- Unusual process creation from image viewing applications
- Crash reports from image processing services
Network Indicators:
- Outbound connections from image processing applications to suspicious IPs
SIEM Query:
Process creation where parent process contains 'Preview', 'Photos', or other image viewing apps AND command line contains unusual image file paths