CVE-2021-1746
📋 TL;DR
CVE-2021-1746 is a vulnerability in Apple's image processing that allows arbitrary code execution when processing a maliciously crafted image. This affects users of macOS, iOS, iPadOS, watchOS, and tvOS who open or view malicious images. Attackers could gain full control of affected devices.
💻 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 attacker gaining root privileges, data theft, ransomware deployment, and persistent backdoor installation.
Likely Case
Malware installation through malicious images delivered via phishing, messaging apps, or compromised websites, leading to data exfiltration or credential theft.
If Mitigated
Limited impact with proper network segmentation, application whitelisting, and user awareness training preventing successful exploitation.
🎯 Exploit Status
Exploitation requires user interaction to open malicious image but no authentication. Apple has not disclosed technical details.
🛠️ 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 on macOS or Settings > General > Software Update on iOS/iPadOS. 2. Install available updates. 3. Restart device when prompted.
🔧 Temporary Workarounds
Disable automatic image processing
allConfigure applications to not automatically process or preview images from untrusted sources
User education
allTrain users to avoid opening images from unknown or untrusted sources
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable devices
- Deploy application control/whitelisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check current OS version against affected versions listCheck 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 matches or exceeds patched versions listed in fix_official.patch_version📡 Detection & Monitoring
Log Indicators:
- Unexpected process crashes in image processing applications
- Suspicious child processes spawned from image viewers
Network Indicators:
- Outbound connections from image processing applications to unknown IPs
SIEM Query:
Process creation events where parent process is image viewer/editor and child process is suspicious (e.g., cmd.exe, powershell.exe, bash)🔗 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
