CVE-2021-30688
📋 TL;DR
This macOS vulnerability allows malicious applications to escape their sandbox restrictions, potentially accessing system resources or other applications' data. It affects macOS Catalina and earlier Big Sur versions before 11.4. Users who haven't updated their macOS are vulnerable to sandbox escape attacks.
💻 Affected Systems
- macOS
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise where a malicious app gains root privileges, accesses sensitive data from other applications, and persists on the system.
Likely Case
Malicious app escapes sandbox to access user data from other applications, potentially stealing credentials, personal files, or other sensitive information.
If Mitigated
Limited impact with proper app vetting and user caution, but still potential for data leakage between applications.
🎯 Exploit Status
Requires user to install and run malicious application. No public exploit code available, but Apple's prompt patching suggests active exploitation was possible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.4 or Security Update 2021-003 for Catalina
Vendor Advisory: https://support.apple.com/en-us/HT212529
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install macOS Big Sur 11.4 update or Security Update 2021-003 for Catalina. 3. Restart computer when prompted.
🔧 Temporary Workarounds
Application Restriction
allOnly install applications from trusted sources like the Mac App Store or identified developers
Gatekeeper Enforcement
allEnsure Gatekeeper is enabled to block apps from unidentified developers
sudo spctl --master-enable
🧯 If You Can't Patch
- Implement application allowlisting to only permit trusted applications
- Use endpoint detection and response (EDR) tools to monitor for sandbox escape attempts
🔍 How to Verify
Check if Vulnerable:
Check macOS version: if running Catalina or Big Sur earlier than 11.4, system is vulnerableCheck Version:
sw_versVerify Fix Applied:
Verify macOS version is 11.4 or later for Big Sur, or has Security Update 2021-003 for Catalina📡 Detection & Monitoring
Log Indicators:
- Unusual process spawning from sandboxed applications
- System policy violations in Unified Logs
Network Indicators:
- Unusual outbound connections from sandboxed applications
SIEM Query:
process where parent_process_name contains "sandbox" and process_name not in allowed_sandbox_processes