CVE-2021-30971
📋 TL;DR
This vulnerability allows attackers to execute arbitrary code or crash applications by tricking users into opening malicious USD (Universal Scene Description) files. It affects macOS, iOS, and iPadOS users running outdated versions. The out-of-bounds write flaw can be exploited without authentication.
💻 Affected Systems
- macOS
- iOS
- iPadOS
📦 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 →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 →⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining code execution at the privilege level of the application processing the USD file, potentially leading to data theft, ransomware deployment, or persistent access.
Likely Case
Application crashes (denial of service) when users open malicious USD files, with potential for limited code execution depending on application context and sandboxing.
If Mitigated
No impact if systems are fully patched or if USD file processing is disabled/restricted.
🎯 Exploit Status
Exploitation requires user interaction to open malicious files. No public exploit code has been disclosed, but the vulnerability is actively patched by Apple.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Monterey 12.1, iOS 15.2, iPadOS 15.2, macOS Big Sur 11.6.2, Security Update 2021-008 Catalina
Vendor Advisory: https://support.apple.com/en-us/HT212976
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install all available updates. 3. Restart the device when prompted. For managed environments, deploy updates via MDM or patch management tools.
🔧 Temporary Workarounds
Disable USD file handling
allRemove or restrict USD file associations to prevent automatic processing
Not applicable - configure via system preferences or MDM policies
Application control
macOSUse application allowlisting to prevent unauthorized applications from processing USD files
Configure via macOS Security & Privacy settings or MDM
🧯 If You Can't Patch
- Implement network filtering to block USD file downloads from untrusted sources
- Educate users to avoid opening USD files from unknown or untrusted sources
🔍 How to Verify
Check if Vulnerable:
Check system version: macOS - About This Mac > macOS version; iOS/iPadOS - Settings > General > About > VersionCheck Version:
macOS: sw_vers -productVersion; iOS/iPadOS: Not available via command line, check SettingsVerify Fix Applied:
Verify installed version matches or exceeds patched versions listed in fix_official.patch_version📡 Detection & Monitoring
Log Indicators:
- Application crashes related to USD file processing
- Console logs showing memory access violations
Network Indicators:
- Downloads of USD files from suspicious sources
- Unusual outbound connections after USD file access
SIEM Query:
source="*console*" AND "USD" AND ("crash" OR "abort" OR "segmentation fault")🔗 References
- https://support.apple.com/en-us/HT212976
- https://support.apple.com/en-us/HT212978
- https://support.apple.com/en-us/HT212979
- https://support.apple.com/en-us/HT212981
- https://support.apple.com/en-us/HT212976
- https://support.apple.com/en-us/HT212978
- https://support.apple.com/en-us/HT212979
- https://support.apple.com/en-us/HT212981
