CVE-2021-1787
📋 TL;DR
CVE-2021-1787 is a privilege escalation vulnerability in Apple operating systems that allows a local attacker to gain elevated privileges. This affects macOS, iOS, iPadOS, watchOS, and tvOS systems running outdated versions. Attackers with local access could potentially execute code with higher privileges than intended.
💻 Affected Systems
- macOS
- iOS
- iPadOS
- watchOS
- tvOS
📦 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...
Learn more about Macos →Tvos by Apple
Watchos by Apple
⚠️ Risk & Real-World Impact
Worst Case
Local attacker gains root/system-level privileges, enabling complete system compromise, data theft, persistence installation, and lateral movement.
Likely Case
Local user or malware with limited privileges escalates to administrator/root access to bypass security controls and install additional payloads.
If Mitigated
With proper patch management and least privilege principles, impact is limited to isolated systems with no critical data access.
🎯 Exploit Status
Requires local access and some user interaction or existing limited privileges. Apple has addressed the logic issues that enabled exploitation.
🛠️ 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.
🔧 Temporary Workarounds
Restrict local access
allLimit physical and remote local access to affected devices through access controls and network segmentation.
🧯 If You Can't Patch
- Implement strict least privilege principles to limit what local users can do even with elevated access
- Isolate affected systems in segmented network zones and monitor for suspicious privilege escalation attempts
🔍 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 affected_systems.versions.Check Version:
macOS: sw_vers -productVersion; iOS/iPadOS: Settings > General > About > VersionVerify Fix Applied:
Verify system version is equal to or newer than the patched versions listed in fix_official.patch_version.📡 Detection & Monitoring
Log Indicators:
- Unexpected privilege escalation events in system logs
- Processes running with unexpected user/group IDs
- Authentication log anomalies for local users
Network Indicators:
- Unusual outbound connections from Apple devices following local user activity
- Lateral movement attempts from Apple devices
SIEM Query:
source="apple_system_logs" AND (event_type="privilege_escalation" OR user_change="root" OR process_elevation="true")🔗 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
