CVE-2021-30788
📋 TL;DR
This vulnerability allows attackers to cause denial-of-service or potentially leak memory contents by tricking users into opening malicious TIFF image files. It affects Apple iOS, macOS, watchOS, and tvOS users who haven't updated to the patched versions.
💻 Affected Systems
- iOS
- macOS
- watchOS
- tvOS
📦 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 →Tvos by Apple
Watchos by Apple
⚠️ Risk & Real-World Impact
Worst Case
Memory disclosure could expose sensitive information like passwords or encryption keys, while denial-of-service could crash affected applications or devices.
Likely Case
Most probable impact is application crashes or device instability when processing malicious TIFF files, potentially requiring device restart.
If Mitigated
With proper patching, the vulnerability is completely eliminated with no residual risk.
🎯 Exploit Status
Exploitation requires user interaction to open malicious TIFF files. No public exploit code has been disclosed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: iOS 14.7, macOS Big Sur 11.5, watchOS 7.6, tvOS 14.7, Security Update 2021-005 Mojave, Security Update 2021-004 Catalina
Vendor Advisory: https://support.apple.com/en-us/HT212600
Restart Required: Yes
Instructions:
1. Open Settings app. 2. Go to General > Software Update. 3. Download and install the latest available update. 4. Restart device when prompted.
🔧 Temporary Workarounds
Disable automatic image preview
allPrevent automatic rendering of TIFF files in email clients and web browsers
User education
allTrain users not to open TIFF files from untrusted sources
🧯 If You Can't Patch
- Implement application whitelisting to block TIFF file processing applications
- Deploy email filtering to block TIFF attachments from untrusted sources
🔍 How to Verify
Check if Vulnerable:
Check current OS version against affected versions list. On macOS: System Preferences > About This Mac. On iOS: Settings > General > About.Check Version:
macOS: sw_vers -productVersion; iOS: Settings > General > About > VersionVerify Fix Applied:
Verify OS version matches or exceeds patched versions listed in the fix information.📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing image files
- Memory access violations in system logs
Network Indicators:
- TIFF file downloads from suspicious sources
- Unusual file transfer patterns
SIEM Query:
source="*system.log*" AND ("crash" OR "segfault") AND ("tiff" OR "image" OR "CGImage")🔗 References
- https://support.apple.com/en-us/HT212600
- https://support.apple.com/en-us/HT212601
- https://support.apple.com/en-us/HT212602
- https://support.apple.com/en-us/HT212603
- https://support.apple.com/en-us/HT212604
- https://support.apple.com/en-us/HT212605
- https://support.apple.com/en-us/HT212600
- https://support.apple.com/en-us/HT212601
- https://support.apple.com/en-us/HT212602
- https://support.apple.com/en-us/HT212603
- https://support.apple.com/en-us/HT212604
- https://support.apple.com/en-us/HT212605
