CVE-2021-30728
📋 TL;DR
This vulnerability allows a malicious application to write data beyond allocated memory bounds in macOS kernel components, potentially leading to arbitrary code execution with kernel privileges. It affects macOS Big Sur, Catalina, and Mojave systems running outdated versions. Attackers could gain complete system control if they can run malicious code on the target machine.
💻 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 privileges, allowing attackers to install persistent malware, steal sensitive data, or disable security controls.
Likely Case
Local privilege escalation where a user with limited access gains kernel privileges to bypass security restrictions or install additional malware.
If Mitigated
Limited impact if systems are fully patched, running modern macOS versions, or have application execution restrictions in place.
🎯 Exploit Status
Exploitation requires local access or ability to execute malicious code. No public proof-of-concept has been disclosed as of knowledge cutoff.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.4, Security Update 2021-003 Catalina, Security Update 2021-004 Mojave
Vendor Advisory: https://support.apple.com/en-us/HT212529
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available security updates. 3. Restart the system when prompted.
🔧 Temporary Workarounds
Application Execution Restrictions
macOSRestrict execution of untrusted applications using macOS Gatekeeper and application whitelisting
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
- Segment vulnerable systems from critical network resources and monitor for suspicious activity
🔍 How to Verify
Check if Vulnerable:
Check macOS version in System Preferences > About This Mac. If version is earlier than specified patched versions, system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version matches or exceeds: Big Sur 11.4, Catalina with Security Update 2021-003, Mojave with Security Update 2021-004📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Unexpected process execution with elevated privileges
- Console.app entries showing memory access violations
Network Indicators:
- Unusual outbound connections from kernel processes
- Suspicious network activity following local privilege escalation
SIEM Query:
process where parent_process_name contains "kernel" and process_name not in (approved_kernel_processes)