CVE-2021-30655
📋 TL;DR
This macOS vulnerability allows applications to execute arbitrary code with system privileges, potentially leading to complete system compromise. It affects macOS Catalina and earlier Big Sur versions before 11.3. All users running vulnerable macOS versions are 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 →⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with root privileges, allowing attacker to install persistent malware, steal all data, and control the entire system.
Likely Case
Malicious application gaining system privileges to bypass security controls, install additional payloads, or access protected system resources.
If Mitigated
Limited impact if proper application sandboxing and least privilege principles are enforced, though system compromise remains possible.
🎯 Exploit Status
Exploitation requires user to run a malicious application. Apple has not disclosed technical details to prevent exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.3 or Security Update 2021-002 Catalina
Vendor Advisory: https://support.apple.com/en-us/HT212325
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install macOS Big Sur 11.3 update or Security Update 2021-002 Catalina. 3. Restart your Mac when prompted.
🔧 Temporary Workarounds
Application Restriction
allRestrict installation and execution of untrusted applications
sudo spctl --master-enable
sudo spctl --enable
🧯 If You Can't Patch
- Implement strict application allowlisting to prevent execution of untrusted applications
- Use endpoint protection software with privilege escalation detection capabilities
🔍 How to Verify
Check if Vulnerable:
Check macOS version: If running Catalina without Security Update 2021-002 or Big Sur before 11.3, system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version is Big Sur 11.3 or later, or Catalina with Security Update 2021-002 installed.📡 Detection & Monitoring
Log Indicators:
- Unexpected privilege escalation events in system logs
- Applications requesting or obtaining root privileges unexpectedly
Network Indicators:
- Downloads of suspicious applications or payloads
SIEM Query:
source="macos_system_logs" AND (event="privilege_escalation" OR process="sudo" OR user="root")