CVE-2020-9941
📋 TL;DR
CVE-2020-9941 is a macOS vulnerability that allows a remote attacker to unexpectedly alter application state through improved checks. This affects macOS systems prior to specific security updates, potentially enabling unauthorized changes to application behavior. Users running older macOS versions without security updates are vulnerable.
💻 Affected Systems
- macOS
📦 What is this software?
Ipados by Apple
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...
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⚠️ Risk & Real-World Impact
Worst Case
Remote attacker could manipulate application behavior to execute arbitrary code, compromise system integrity, or steal sensitive data.
Likely Case
Attacker could cause application crashes, modify application settings, or perform limited unauthorized actions within vulnerable applications.
If Mitigated
With proper patching, the vulnerability is eliminated; with network segmentation, attack surface is reduced but not eliminated.
🎯 Exploit Status
Exploitation likely requires user interaction or specific application conditions. No public exploit code available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Catalina 10.15.7, Security Update 2020-005 High Sierra, Security Update 2020-005 Mojave
Vendor Advisory: https://support.apple.com/en-us/HT211849
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install available security updates. 3. Restart computer when prompted.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to vulnerable macOS systems to reduce attack surface
Application Whitelisting
macOSUse application control to limit which applications can run and modify system state
🧯 If You Can't Patch
- Isolate vulnerable systems from untrusted networks and internet access
- Implement strict application control policies and monitor for unusual application behavior
🔍 How to Verify
Check if Vulnerable:
Check macOS version: 1. Click Apple menu > About This Mac. 2. If version is earlier than Catalina 10.15.7, High Sierra without Security Update 2020-005, or Mojave without Security Update 2020-005, system is vulnerable.Check Version:
sw_versVerify Fix Applied:
After update, verify macOS version shows Catalina 10.15.7 or later, or shows Security Update 2020-005 installed for High Sierra/Mojave.📡 Detection & Monitoring
Log Indicators:
- Unexpected application crashes
- Unusual application state changes in system logs
- Security framework violation logs
Network Indicators:
- Unusual network connections from macOS applications
- Suspicious inbound connections to macOS systems
SIEM Query:
source="macOS" AND (event_type="application_crash" OR event_type="security_violation") AND NOT process_name IN ("expected_processes")🔗 References
- http://seclists.org/fulldisclosure/2020/Dec/32
- http://seclists.org/fulldisclosure/2020/Nov/20
- http://seclists.org/fulldisclosure/2020/Nov/21
- http://seclists.org/fulldisclosure/2020/Nov/22
- https://support.apple.com/en-us/HT211849
- https://support.apple.com/kb/HT211844
- https://support.apple.com/kb/HT211850
- https://support.apple.com/kb/HT211931
- http://seclists.org/fulldisclosure/2020/Dec/32
- http://seclists.org/fulldisclosure/2020/Nov/20
- http://seclists.org/fulldisclosure/2020/Nov/21
- http://seclists.org/fulldisclosure/2020/Nov/22
- https://support.apple.com/en-us/HT211849
- https://support.apple.com/kb/HT211844
- https://support.apple.com/kb/HT211850
- https://support.apple.com/kb/HT211931
