Update Mobile Application Security Cheat Sheet with iOS-Specific Guidelines

cheatsheets/Mobile_Application_Security_Cheat_Sheet.md

@@ -246,11 +246,44 @@ examples of data that should not be logged.
   on working with data securely for more details.
 - Disable backup mode to prevent sensitive data being stored in backups.
 
-### iOS
+### iOS and iPadOS
 
-- Use ATS (App Transport Security) to enforce strong security policies for
-  network communication.
-- Do not store sensitive data in plist files.
+#### Shortcuts Permissions
+
+- iOS/iPadOS Shortcuts allow for automation of app functions, which may enable sensitive actions even when the device is locked.
+- There are several scenarios in which a user can execute a Shortcut while the device is locked:
+1. If a Shortcut is added as a widget to Today View, it can be accessed and executed while the device is locked.
+2. If a Shortcut is assigned to the Action Button (on iPhone 15 Pro and iPhone 16 Pro models), it can be executed by pressing the Action Button while the device is locked.
+3. If a Shortcut is assigned to the Control Center (on iOS/iPadOS 18+), it can be executed by pulling up the Control Center and pressing the Shortcut button while the device is locked.
+4. A Shortcut can be invoked via Siri while the device is locked.
+5. If a Shortcut is added to the user's Home Screen (on iOS/iPadOS 18+), it can be directly executed by tapping the Shortcut button on the user's lock screen while the device is locked.
+6. If a Shortcut is set to run at a specific interval or a specific time, it can execute even if the device is locked. 
+- Sensitive app functionalities triggered via Shortcuts should always require device unlock before execution.
+- **How**: Store secure tokens in Keychain that the app validates before executing sensitive shortcuts. Implement checks with `UIApplication.shared.isProtectedDataAvailable` to restrict execution of sensitive actions when the device is locked.
+
+#### Siri Permissions
+
+- Siri can access app functionalities through voice or [Type to Siri](https://support.apple.com/guide/iphone/change-siri-accessibility-settings-iphaff1d606/ios#:~:text=Type%20instead%20of%20speak%20to,this%20option%20isn't%20shown.) commands, which is by default accessible even when the device is locked, potentially enabling unauthorized actions.
+- **How**: Configure `requiresUserAuthentication` to `true` on intents that expose sensitive information or functionality. Additionally, set `INIntent.userConfirmationRequired = true` for operations requiring explicit user confirmation. These settings ensure proper authentication (e.g., Face ID or PIN) and explicit approval before Siri can execute sensitive commands. (For more information, see Apple Developer's [SiriKit](https://developer.apple.com/documentation/sirikit) documentation.)
+
+#### Deep Link Security
+
+- Deep links offer direct access to specific app screens, which could potentially bypass authentication if not secured, allowing unauthorized users access to secure sections of the app.
+- An example of this on Microsoft Authenticator for iOS (which was remediated in July 2024) allowed users to bypass App Lock by simply navigating to `msauth://microsoft.aad.brokerplugin/?`, which would open Authenticator and dismiss the Face ID/Touch ID/passcode prompt.
+- **How**: Implement authentication checks on any view controllers or endpoints accessed via deep links. Configure and validate Universal Links using apple-app-site-association files for secure deep linking. Sanitize and validate all parameters received through deep links to prevent injection attacks. Ensure unauthorized users are redirected to the login screen, preventing direct access to sensitive parts of the app without proper authentication. (See Apple Developer's [Supporting universal links in your app](https://developer.apple.com/documentation/xcode/supporting-universal-links-in-your-app) documentation for more information.)
+
+#### WidgetKit Security
+
+- Widgets on the lock screen may display sensitive data, potentially exposing it without the device being unlocked.
+- **How**: For iOS/iPadOS versions 17 and higher, use `WidgetInfo.isLocked` to detect lock screen state. For earlier iOS versions, implement custom logic based on available widget states since `widgetFamily` alone doesn't directly provide lock screen information. Apply conditional logic to mask or restrict sensitive widget content when appropriate security conditions aren't met. (See Apple's [WidgetKit security](https://support.apple.com/guide/security/widgetkit-security-secbb0a1f9b4/web) for more information.)
+
+#### Additional Security Considerations
+
+- Configure appropriate background refresh policies to prevent sensitive data updates while the device is locked.
+- Implement proper privacy-related configurations in `Info.plist` for features requiring user permissions.
+- Use App Groups with appropriate security configurations when sharing data between app and widgets.
+- Use ATS (App Transport Security) to enforce strong security policies for network communication.
+- Do not store sensitive data in `plist` files.
 
 For further reading, visit the
 [OWASP Mobile Top 10 Project](https://owasp.org/www-project-mobile-top-10/).