CVE-2021-30777
📋 TL;DR
This macOS vulnerability allows malicious applications to inject code and gain root privileges through improper input validation. It affects macOS Big Sur, Catalina, and Mojave systems running outdated versions. Attackers could execute arbitrary code with the highest system privileges.
💻 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 root-level persistence, data theft, and backdoor installation
Likely Case
Local privilege escalation allowing malicious apps to bypass security controls and access protected resources
If Mitigated
Limited impact with proper application sandboxing and user awareness preventing malicious app execution
🎯 Exploit Status
Requires user interaction to execute malicious application. No public exploit code available at disclosure.
🛠️ 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 updates. 3. Restart when prompted.
🔧 Temporary Workarounds
Application Execution Control
allRestrict execution of untrusted applications using Gatekeeper and parental controls
sudo spctl --master-enable
sudo spctl --enable
🧯 If You Can't Patch
- Implement strict application allowlisting to prevent execution of untrusted software
- Use standard user accounts instead of admin accounts for daily use to limit privilege escalation impact
🔍 How to Verify
Check if Vulnerable:
Check macOS version in About This Mac > System Report > Software > System VersionCheck Version:
sw_versVerify Fix Applied:
Verify version is Big Sur 11.5+, or check Security Update installation in System Preferences > Software Update > History📡 Detection & Monitoring
Log Indicators:
- Unexpected privilege escalation in system.log
- Unauthorized root process execution
Network Indicators:
- None - local exploitation only
SIEM Query:
process where parent_process_name in ("sh", "bash", "zsh") and user="root" and parent_user!="root"