CVE-2020-9771
📋 TL;DR
This macOS vulnerability allows a user to bypass file system protections and access restricted areas. It affects macOS Catalina versions before 10.15.4. The issue was resolved through a new entitlement mechanism in the operating system.
💻 Affected Systems
- macOS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An attacker could access sensitive system files, user data, or protected directories, potentially leading to privilege escalation, data theft, or system compromise.
Likely Case
Local users could access files they shouldn't have permission to view, violating file system security boundaries and potentially accessing other users' data.
If Mitigated
With proper access controls and updated systems, the vulnerability is eliminated, maintaining normal file system security boundaries.
🎯 Exploit Status
Requires local access to the system. Apple addressed this with a new entitlement, suggesting it involves bypassing existing permission checks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Catalina 10.15.4
Vendor Advisory: https://support.apple.com/kb/HT211100
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install macOS Catalina 10.15.4 update. 3. Restart the computer when prompted.
🔧 Temporary Workarounds
Restrict local user access
allLimit which users have local access to vulnerable systems to reduce attack surface
🧯 If You Can't Patch
- Implement strict file system permissions and access controls
- Monitor for unusual file access patterns and audit file system logs
🔍 How to Verify
Check if Vulnerable:
Check macOS version: If running macOS Catalina and version is earlier than 10.15.4, system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version is 10.15.4 or later via System Information or terminal command.📡 Detection & Monitoring
Log Indicators:
- Unusual file access patterns in system logs
- Access to protected directories by unauthorized users
Network Indicators:
- Not applicable - local vulnerability
SIEM Query:
Search for file access events to protected system directories from non-privileged users