Intune App SDK for iOS - Web-view features
Displaying web content within an application
In iOS, web views can be used to surface a wide variety of web content without having to leave the context of the app. Some applications might also use web views as a way of sharing features and UI across multiple platforms.
Because web views exist within the app, they expose it to potential data leaks. If a user is able to navigate to arbitrary external web pages within an app (either through intentional app design or by clever maneuvering through exposed links in the rendered web page's html content), then the user may be able to leak managed data from the app.
The Intune MAM SDK provides several APIs for handling different scenarios where both managed and unmanaged content are surfaced through web views within an app. These APIs only need to be called if there is a managed user signed into the app. Please see the table below as a quick guide on which API applies to which scenario.
| Scenario | APIs |
|---|---|
| Only user and organizational content with no risk of arbitrary web pages | No APIs needed |
| Only non-user and non-organizational content | Set TreatAllWebViewsAsUnmanaged in the Info.plist |
| A mix of user/organizational and non-user/non-organizational content (majority non-user/non-organizational) | Set TreatAllWebViewsAsUnmanaged in the Info.plist and use setWebViewPolicy:forWebViewer: with IntuneMAMWebViewPolicyCurrentIdentity on web views that contain user or organizational data |
| A mix of user/organizational and non-user/non-organizational content (majority user/organizational) | Only use setWebViewPolicy:forWebViewer: with IntuneMAMWebViewPolicyUnmanaged on web views that don't contain user or organizational data |
| User or organizational content but with a risk of arbitrary web pages | Following suitable usage of TreatAllWebViewsAsUnmanaged and setWebViewPolicy:forWebViewer:, also implement the IntuneMAMWebViewPolicyDelegate for web views that might navigate to arbitrary web pages |
Web View Scenario 1: Only web pages that display user or organizational content
If an app only uses web views as a way of rendering user or organizational content and there's no risk of the web view navigating to arbitrary external web pages, then there's no need to use any of the APIs or settings. By default, the SDK will treat any web view surfaced within the app as content belonging to the current UI policy identity.
If a managed user opens a web view within an app, any cut/copy data from the web view will be treated as managed content. Pasting into the web view will be treated according to the managed account's policies.
If an unmanaged user opens a web view within an app, any cut/copy data from the web view will be treated as unmanaged content. Pasting into the web view will be treated as if done by the unmanaged account and no additional restrictions will be imposed.
Web View Scenario 2: Only web pages that don't display user or organizational content
If an app knows that it will never display user or organizational content within a web view, then it can set TreatAllWebViewsAsUnmanaged to YES in the app's Info.plist. This will treat all cut, copy, and paste actions done by any user within a web view as unmanaged. Regardless of the management status of the account used to perform the actions, the action will be treated as if performed by an unmanaged user.
Doing so will ensure that managed app content isn't leaked outside the app through the web view. Setting this flag would be a good idea if an app only uses web views to display privacy notices, EULAs, or other static page content that doesn't require a user to view it.
When TreatAllWebViewsAsUnmanaged is set, all content displayed within the web views can be copied and pasted to other unmanaged apps since the web views themselves are considered unmanaged.
Web View Scenario 3: A mix of user/organizational and non-user/non-organizational content
More complex apps might use a combination of user/organizational and non-user/non-organizational web views. An app might use web views to display privacy notices but also use web views to surface user content. In this case, the IntuneMAMPolicyManager's setWebViewPolicy:forWebViewer: API can be used. This API allows an app to mark individual web views as unmanaged or undo the effect of TreatAllWebViewsAsUnmanaged for individual web views.
The API takes two arguments. The first is an enum value of IntuneMAMWebViewPolicy type. The second can be either a UIView or UIViewController that may contain a WKWebView in its child view hierarchy. A WKWebView itself can also be passed in directly as the second argument.
If the WKWebView is a child of the UIView or UIViewController passed in as the second argument, it does not have to exist within the view hierarchy at the time this API is called. Any child WKWebViews of the passed in UIView or UIViewController will have the proper policy applied when they are added.
IntuneMAMWebViewPolicyUnset- This is the default policy for all WKWebViews. Web views will be treated according to only theTreatAllWebViewsAsUnmanagedflag.IntuneMAMWebViewPolicyUnmanaged- Any cut/copy/paste actions performed by a user on a web view tagged with this policy will be treated as if performed by an unmanaged identity. This policy will overwrite theTreatAllWebViewsAsUnmanagedflag.IntuneMAMWebViewPolicyCurrentIdentity- Any cut/copy/paste actions performed by a user on a web view tagged with this policy will be treated as if performed by the current UI policy identity. This policy will overwrite theTreatAllWebViewsAsUnmanagedflag.
Majority non-user and non-organizational data
If a majority of the web views within an app display unmanaged content, then TreatAllWebViewsAsUnmanaged can be set in the app's Info.plist and setWebViewPolicy:forWebViewer: with IntuneMAMWebViewPolicyCurrentIdentity can be called on the user or organizational content web views.
Majority user and organizational data
If a majority of the web views within an app display user or organizational content, then only setWebViewPolicy:forWebViewer: with IntuneMAMWebViewPolicyUnmanaged needs to be called on the unmanaged web views since all web views are treated as managed by default.
Web View Scenario 4: User or organizational content but with a risk of arbitrary web pages
If a web view is used to display user or organizational content but has a risk of navigating to arbitrary external URLs, then an additional API can be used in combination with TreatAllWebViewsAsUnmanaged and setWebViewPolicy:forWebViewer:. Examples of this are Suggest a Feature or Feedback webpages that have either direct or indirect links to a search engine.
IntuneMAMWebViewPolicyDelegate can be implemented and set to a web view using IntuneMAMPolicyManager's setWebViewPolicyDelegate:forWebViewer:. The IntuneMAMWebViewPolicyDelegate has one required method, isExternalURL:.
The setWebViewPolicyDelegate:forWebViewer: method must be called directly on a WKWebView or SFSafariViewController.
Each time the web view navigates to a new page, the isExternalURL: delegate method will be called. Applications should determine if the URL passed to the delegate method represents an internal website where user or organizational data can be pasted in or an external website that could leak organizational data. Returning NO will tell the SDK that the website being loaded is an organizational location where user or organizational data can be shared. Returning YES will cause the SDK to open the URL in a managed browser rather than the WKWebView or SFSafariViewController if current policy settings require it. This will ensure that no user or organizational data from within the app can be leaked to the external website.
Web View APIs Example
An app is built with five web views (A, B, C, D, and E). Web views A, B, and C don't display user or organizational data. Web view D displays an organization page available to all users of the company. Web view E renders the user's documents which may contain links.
Since the majority of web views are unmanaged (A, B, and C), we can set TreatAllWebViewsAsUnmanaged to reduce the number of times we need to call setWebViewPolicy:forWebViewer:.
Since web views D and E display user content and all web views are unmanaged by default now, we need to tag them with setWebViewPolicy:forWebViewer: using IntuneMAMWebViewPolicyCurrentIdentity.
Because web view E contains links that the user might click on and could use to navigate to arbitrary URLs, we also need to implement the IntuneMAMWebViewPolicyDelegate and set it to web view E using setWebViewPolicyDelegate:forWebViewer:. In our isExternalURL: implementation, we could check incoming URLs and see if they are the same as the URL for the document. If they don't match, then we know it's an external URL and can return YES. If they do match, then we know it's an internal URL and can return NO.
Implementing and calling these APIs means that managed user or organizational content can't leak to web views A, B, and C. It also means that managed content can't leak to any external URLs that the user might navigate to in E by clicking on links within documents. Managed content will also be protected by preventing the data from web views D and E from leaking outside the app.
SwiftUI Support
A newly created SwiftUI app supports UIScenes but doesn't have a UISceneDelegate implemented by default. If your app intends to support UIScenes and use the Intune App SDK, then it's required to implement a UISceneDelegate. If it doesn't intend to support UIScenes, the UIApplicationSceneManifest (also named "Application Scene Manifest") setting in the app's Info.plist must be removed.