CVE-2021-30793
📋 TL;DR
This macOS kernel vulnerability allows malicious applications to execute arbitrary code with kernel privileges, potentially taking full control of affected systems. It affects macOS Big Sur, Catalina, and Mojave versions before specific security updates. Any user running unpatched macOS versions is vulnerable to local privilege escalation 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 with kernel-level access, allowing attackers to install persistent malware, steal all data, disable security controls, and use the system as a foothold for lateral movement.
Likely Case
Local privilege escalation where a standard user or malicious application gains kernel privileges to bypass security restrictions and install additional payloads.
If Mitigated
Limited impact if systems are patched, running with minimal privileges, and have additional security controls like endpoint protection and application allowlisting.
🎯 Exploit Status
Requires local access or ability to run malicious application. Apple has not disclosed technical details, but kernel vulnerabilities are often targeted by sophisticated attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.5, Security Update 2021-004 Catalina, Security Update 2021-005 Mojave
Vendor Advisory: https://support.apple.com/en-us/HT212600
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available security updates. 3. Restart when prompted. 4. Verify update installation in About This Mac.
🔧 Temporary Workarounds
Application Restriction
allRestrict execution of untrusted applications using macOS security features
sudo spctl --master-enable
sudo spctl --enable --label "Developer ID"
🧯 If You Can't Patch
- Implement strict application control policies to prevent execution of untrusted applications
- Use endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check macOS version in About This Mac > Overview. If version is Big Sur < 11.5, Catalina without Security Update 2021-004, or Mojave without Security Update 2021-005, system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version shows Big Sur 11.5 or higher, or that security updates are listed as installed in System Preferences > Software Update > Info.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Unexpected privilege escalation in audit logs
- Suspicious process creation with elevated privileges
Network Indicators:
- Unusual outbound connections from kernel processes
- Command and control traffic following local exploitation
SIEM Query:
process where parent_process_name contains "kernel" and process_name not in (expected_kernel_processes)