CVE-2021-30678
📋 TL;DR
CVE-2021-30678 is a critical logic vulnerability in macOS that allows remote attackers to cause application crashes or execute arbitrary code. This affects macOS Big Sur, Catalina, and Mojave systems. Attackers can exploit this without authentication to potentially take full control of affected systems.
💻 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 remote code execution leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Application crashes leading to denial of service, followed by potential privilege escalation and limited code execution.
If Mitigated
Limited impact with proper network segmentation and endpoint protection, though still vulnerable to internal threats.
🎯 Exploit Status
Apple's description suggests this is a logic issue with improved state management, typically indicating a race condition or state confusion vulnerability that could be reliably exploited.
🛠️ 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 your Mac when prompted. 4. Verify installation by checking macOS version in About This Mac.
🔧 Temporary Workarounds
Network Segmentation
allIsolate vulnerable macOS systems from untrusted networks and internet access.
Endpoint Protection
allDeploy advanced endpoint detection and response (EDR) solutions to detect exploitation attempts.
🧯 If You Can't Patch
- Implement strict network access controls to limit exposure to trusted sources only.
- Deploy application whitelisting and memory protection controls to limit impact of potential exploitation.
🔍 How to Verify
Check if Vulnerable:
Check macOS version: 1. Click Apple menu > About This Mac. 2. If version is Big Sur < 11.4, Catalina without Security Update 2021-003, or Mojave without Security Update 2021-004, system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version shows Big Sur 11.4 or higher, or that Security Updates 2021-003/004 are installed in System Report > Software > Installations.📡 Detection & Monitoring
Log Indicators:
- Unexpected application crashes in system logs
- Memory access violations
- Process creation from unexpected sources
Network Indicators:
- Unusual outbound connections from macOS systems
- Network traffic to unexpected destinations
SIEM Query:
source="macos_system_logs" AND (event="crash" OR event="segfault") AND process="*" | stats count by host, process