CVE-2021-1818
📋 TL;DR
CVE-2021-1818 is a critical logic vulnerability in Apple operating systems that allows remote attackers to cause application crashes or execute arbitrary code. This affects macOS, iOS, iPadOS, watchOS, and tvOS systems running outdated versions. The vulnerability stems from improper state management that can be exploited remotely.
💻 Affected Systems
- macOS
- iOS
- iPadOS
- watchOS
- tvOS
📦 What is this software?
Ipad Os 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...
Learn more about Macos →Tvos by Apple
Watchos by Apple
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker gains full system control and executes arbitrary code with highest privileges, potentially leading to complete system compromise.
Likely Case
Remote attacker causes application termination (DoS) or executes code with user-level privileges, enabling data theft, surveillance, or lateral movement.
If Mitigated
With proper network segmentation and least privilege, impact limited to isolated systems with minimal data exposure.
🎯 Exploit Status
Apple's description suggests remote exploitation without authentication. The CVSS 9.8 score indicates low attack complexity and no privileges required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, watchOS 7.3, tvOS 14.4, iOS 14.4, iPadOS 14.4
Vendor Advisory: https://support.apple.com/en-us/HT212146
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update on macOS or Settings > General > Software Update on iOS/iPadOS. 2. Download and install the latest security update. 3. Restart the device when prompted. 4. Verify the update completed successfully.
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected Apple devices from untrusted networks and internet exposure
Application Whitelisting
allRestrict execution of unauthorized applications to limit impact of code execution
🧯 If You Can't Patch
- Isolate affected systems in separate network segments with strict firewall rules
- Implement application control solutions to prevent execution of unauthorized code
🔍 How to Verify
Check if Vulnerable:
Check system version: On macOS, go to Apple menu > About This Mac. On iOS/iPadOS, go to Settings > General > About. Compare with patched versions listed in fix_official.patch_version.Check Version:
macOS: sw_vers -productVersion; iOS/iPadOS: Settings > General > About > VersionVerify Fix Applied:
Verify system version matches or exceeds patched versions. Check that security updates show as installed in Software Update history.📡 Detection & Monitoring
Log Indicators:
- Unexpected application crashes
- Process creation from unexpected sources
- System logs showing memory access violations
Network Indicators:
- Unusual outbound connections from Apple devices
- Network traffic patterns matching exploit attempts
SIEM Query:
source="apple_system_logs" AND (event="crash" OR event="segfault") AND device_type IN ("macOS", "iOS", "iPadOS")🔗 References
- https://support.apple.com/en-us/HT212146
- https://support.apple.com/en-us/HT212147
- https://support.apple.com/en-us/HT212148
- https://support.apple.com/en-us/HT212149
- https://support.apple.com/en-us/HT212146
- https://support.apple.com/en-us/HT212147
- https://support.apple.com/en-us/HT212148
- https://support.apple.com/en-us/HT212149
