Testing Enforced Updating
Overview¶
To test for enforced updating you need to check if the app has support for in-app updates and validate if it's properly enforced so that the user is not able to continue using the app without updating it first.
Static analysis¶
The code sample below shows the example of an app-update:
//Part 1: check for update
// Creates instance of the manager.
AppUpdateManager appUpdateManager = AppUpdateManagerFactory.create(context);
// Returns an intent object that you use to check for an update.
Task<AppUpdateInfo> appUpdateInfo = appUpdateManager.getAppUpdateInfo();
// Checks that the platform will allow the specified type of update.
if (appUpdateInfo.updateAvailability() == UpdateAvailability.UPDATE_AVAILABLE
// For a flexible update, use AppUpdateType.FLEXIBLE
&& appUpdateInfo.isUpdateTypeAllowed(AppUpdateType.IMMEDIATE)) {
//...Part 2: request update
appUpdateManager.startUpdateFlowForResult(
// Pass the intent that is returned by 'getAppUpdateInfo()'.
appUpdateInfo,
// Or 'AppUpdateType.FLEXIBLE' for flexible updates.
AppUpdateType.IMMEDIATE,
// The current activity making the update request.
this,
// Include a request code to later monitor this update request.
MY_REQUEST_CODE);
//...Part 3: check if update completed successfully
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (myRequestCode == MY_REQUEST_CODE) {
if (resultCode != RESULT_OK) {
log("Update flow failed! Result code: " + resultCode);
// If the update is cancelled or fails,
// you can request to start the update again in case of forced updates
}
}
}
//..Part 4:
// Checks that the update is not stalled during 'onResume()'.
// However, you should execute this check at all entry points into the app.
@Override
protected void onResume() {
super.onResume();
appUpdateManager
.getAppUpdateInfo()
.addOnSuccessListener(
appUpdateInfo -> {
...
if (appUpdateInfo.updateAvailability()
== UpdateAvailability.DEVELOPER_TRIGGERED_UPDATE_IN_PROGRESS) {
// If an in-app update is already running, resume the update.
manager.startUpdateFlowForResult(
appUpdateInfo,
IMMEDIATE,
this,
MY_REQUEST_CODE);
}
});
}
}
Source: https://developer.android.com/guide/app-bundle/in-app-updates
Dynamic analysis¶
In order to test for proper updating: try downloading an older version of the application with a security vulnerability, either by a release from the developers or by using a third party app-store. Next, verify whether or not you can continue to use the application without updating it. If an update prompt is given, verify if you can still use the application by canceling the prompt or otherwise circumventing it through normal application usage. This includes validating whether the backend will stop calls to vulnerable backends and/or whether the vulnerable app-version itself is blocked by the backend. Lastly, see if you can play with the version number of a man-in-the-middled app and see how the backend responds to this (and if it is recorded at all for instance).