CVE-2021-30935
📋 TL;DR
This macOS kernel vulnerability allows malicious applications to execute arbitrary code with kernel privileges, potentially gaining full system control. It affects macOS Catalina and Big Sur systems before specific security updates. Any user running vulnerable macOS versions is at risk.
💻 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 →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 with attacker gaining kernel-level privileges, allowing installation of persistent malware, data theft, and system manipulation.
Likely Case
Malicious application escalates privileges to kernel level, enabling system-wide access and potential data exfiltration.
If Mitigated
Limited impact with proper application sandboxing and security controls, though kernel access remains dangerous.
🎯 Exploit Status
Requires user to execute malicious application. Kernel privilege escalation vulnerabilities are highly valuable to attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Security Update 2021-008 for Catalina, macOS Big Sur 11.6.2
Vendor Advisory: https://support.apple.com/en-us/HT212979
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install Security Update 2021-008 (Catalina) or macOS Big Sur 11.6.2. 3. Restart when prompted.
🔧 Temporary Workarounds
Application Restriction
allRestrict installation and execution of untrusted applications
sudo spctl --master-enable
sudo spctl --enable --label "Developer ID"
🧯 If You Can't Patch
- Implement strict application allowlisting to prevent execution of untrusted software
- Use network segmentation to isolate vulnerable systems from critical assets
🔍 How to Verify
Check if Vulnerable:
Check macOS version: Catalina should be 10.15.7 with Security Update 2021-008, Big Sur should be 11.6.2 or laterCheck Version:
sw_versVerify Fix Applied:
Verify installed updates in System Preferences > Software Update > Installed Updates📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Unexpected privilege escalation in system logs
- Suspicious application execution with elevated privileges
Network Indicators:
- Unusual outbound connections from system processes
- Command and control traffic from kernel-level processes
SIEM Query:
source="macos_system_logs" AND (event="kernel_panic" OR process_privilege="kernel")