CVE-2021-1849
📋 TL;DR
This vulnerability allows malicious applications to bypass code signature validation checks, potentially circumventing macOS and iOS privacy preferences. It affects Apple devices running older versions of macOS Big Sur, iOS, iPadOS, watchOS, and tvOS before the patched releases.
💻 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
Malicious applications could access sensitive user data (contacts, photos, location) without user consent by bypassing privacy permission dialogs.
Likely Case
Malware or spyware could be installed that appears legitimate but bypasses Apple's code signature validation, potentially accessing protected data.
If Mitigated
With proper controls, the risk is limited to applications that users manually install from outside the App Store, as App Store apps undergo additional review.
🎯 Exploit Status
Exploitation requires user interaction to install a malicious application. No public exploit code has been disclosed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.3, iOS 14.5, iPadOS 14.5, watchOS 7.4, tvOS 14.5
Vendor Advisory: https://support.apple.com/en-us/HT212317
Restart Required: Yes
Instructions:
1. Go to Settings > General > Software Update on iOS/iPadOS/watchOS/tvOS or System Preferences > Software Update on macOS. 2. Download and install the available update. 3. Restart the device when prompted.
🔧 Temporary Workarounds
Restrict application sources
allConfigure devices to only allow installation from the App Store, preventing installation of potentially malicious applications from other sources.
On macOS: System Preferences > Security & Privacy > General > Allow apps downloaded from: App Store
On iOS/iPadOS: Settings > General > Device Management > Enable restrictions if available
🧯 If You Can't Patch
- Implement application allowlisting to only permit trusted applications to run.
- Educate users to only install applications from the official App Store and avoid third-party sources.
🔍 How to Verify
Check if Vulnerable:
Check the current OS version against the affected versions listed in the affected_systems section.Check Version:
On macOS: sw_vers -productVersion; On iOS/iPadOS: Settings > General > About > Version; On watchOS: Watch app on iPhone > General > About > Version; On tvOS: Settings > General > About > VersionVerify Fix Applied:
Verify the OS version is equal to or newer than the patched versions: macOS 11.3+, iOS 14.5+, iPadOS 14.5+, watchOS 7.4+, tvOS 14.5+.📡 Detection & Monitoring
Log Indicators:
- Unexpected application installations from non-App Store sources
- Privacy permission alerts for unfamiliar applications
Network Indicators:
- Connections to unknown domains by newly installed applications
SIEM Query:
Search for events related to application installation or code signature validation failures in system logs.🔗 References
- https://support.apple.com/en-us/HT212317
- https://support.apple.com/en-us/HT212323
- https://support.apple.com/en-us/HT212324
- https://support.apple.com/en-us/HT212325
- https://support.apple.com/en-us/HT212317
- https://support.apple.com/en-us/HT212323
- https://support.apple.com/en-us/HT212324
- https://support.apple.com/en-us/HT212325
