Develop Reference

My Flutter app blocks all requests on some Android models

I've been having some problems with my app in production, some Huawei users have complained that the app doesn't leave the home page. When I go to see the log requests, I see that no requests are made. Any other users do not have this problem.
I don't know if it's a problem with the type of processor the phone uses, or if there's some sort of firewall blocking.
Any suggestion?

Have you checked usecleartext attribute in AndroidManifest.xml? Maybe you are trying to communicate a non-https service.
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Which android API calls need these permission?

I'm trying to figure out which android API calls need these permissions:
android.permission.HARDWARE_TEST
android.permission.DEVICE_POWER
android.permission.DIAGNOSTIC
android.permission.GET_TOP_ACTIVITY_INFO
I read the descriptions on the Android developer website, but I found no way to perform the operations that these permissions allow.
EDIT after HexAndBugs answer: I know these permission are not intended for third-party application, but I'd like to use them in a experimental environment, playing the role of the manufacturer.

These aren't intended to be used in your apps (unless you are a device manufacturer), so you won't find things that need them in the API. Note that they all say Not for use by third-party applications. See, for example, DEVICE_POWER

Although these settings are not for usual app but if you have a rooted device and you need to control, lets say hardware test then you would have to add it to your apps permisson and override the ususal CET testing pannel
But FYI it can brick the phone or device if you tweaksomething wrong so beaware;
i personally have used couple of these permisson for e.g getTop Activity info to monitor that my app is always on foreground

Permission check event (or log) for Android

I understand that when you install an android app you need to accept the permissions requested by the app. When you run the app, when it comes to the point that app really about to use that permission and perform a task, the android system has to check again "whether this app is allowed to perform this task?". I need to perform some task (log the event) at this moment. How can I do this?
There is a catch. I want to identify these instances (moments) for other running apps (not for my app)
(Ex: I want to know when DropBox app is about to access the internet.)

I need to perform some task (log the event) at this moment. How can I do this?
You can download the Android source code, modify it to incorporate your desired security flaw, compile the results into a ROM mod, and install that ROM mod on your own device.
This is not possible via the Android SDK.
There is a catch. I want to identify these instances (moments) for other running apps (not for my app) (Ex: I want to know when DropBox app is about to access the internet.)
You are welcome to install and use a firewall package on your rooted Android device and perhaps hook something up that way, for this specific scenario. In general, what you seek is not possible, for blindingly obvious privacy and security reasons.

How do I determine why my Android app requires certain permissions?

Let's say I have taken over development of an Android app, and my boss asks me why our app requires certain permissions to be displayed to users who buy the app on the Android Market.
Are there any tools or tricks I can use to determine what code triggers each permission, so I can figure out why our app functionally needs those permissions? In particular, I am interested in these permissions:
Phone Calls - Read phone status and identity
System Tools - Retrieve running applications - Allows app to retrieve information about currently and recently running tasks, May allow malicious apps to discover private information about other apps.
The app is a GPS tracking app, and it's not obvious why this permission might be needed.
It would also be helpful to get any tips on why this permission might be needed, even if you can't tell me how to directly analyze the code to find out.

Here is how I would track these down.
Step 1 - Find the manifest permissions declared in your AndroidManifest.xml
Basically everything inside the <uses-permission /> tags e.g.:
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
Step 2 - Search developer.android.com for classes that use these permissions
Let's take the case of READ_PHONE_STATE, the goal is to find which packages require this permission. A simple search on the dev portal for "READ_PHONE_STATE" starts our search, we are looking for classes here, in the top 5 search results I see the following classes:
TelephonyManager
PhoneStateListener
Click on the classes and get their package names:
android.telephony.TelephonyManager
android.telephony.PhoneStateListener
Step 3 Find classes in your project that import these packages
A simple grep will do, or a Ctrl-H in eclipse, File Search -> Containing text
Step 4 Comment out the import and see what breaks
These are likely candidates for why the permission is required. Confirm the methods in question by looking at the dev portal to validate that the permission is indeed required by that method.
Finally you should be able to tell your boss, READ_PHONE_STATE is required because we call function XYZ which gives us UVW.

Remove a permission and see where the app fails. The answer will be in the logcat output.
That's not an ideal solution though, since you might not know what you need to do in the app to trigger that permission.
I suspect "Read phone status and identity" means that the app is using the device IMEI or similar identifying information to uniquely identify the device to ensure that the app is only being run on a registered device. Or it might just be used as a sort of cookie to track the owner. Look for that code. And remove it, because that's the wrong way to do it. If you need to identify a specific android device, use ANDROID_ID from the Settings.Secure class. http://developer.android.com/reference/android/provider/Settings.Secure.html
As for "Retrieve running applications", I find that one somewhat suspicious. A very common way to implement GPS tracking is to launch a separate service in its own process. This way, if the app should crash, the service will keep going and can be re-attached. In this case, it's possible that the app is using the "Retrieve running applications" to identify and kill the service process. But if so, it's a clumsy way to do it.

With the latest build tools, you can run lint check which will highlight for you all the android SDK method calls which are requiring permissions.
See announcement here http://android-developers.blogspot.com/2015/07/get-your-hands-on-android-studio-13.html and documentation here https://developer.android.com/tools/debugging/annotations.html#permissions .
This is based on android annotations and after some adoption time 3rd party libraries can integrate permission annotations also

The answer for your boss is "because certain API features/calls/methods we use in our app require calee to hold certain permissions. It is for security reasons, and that's the way Android works". As for mentioned permissions - you have to check the code to see if these permissions are really required. Read phone status and identity may indicate your app try to get IMEI or something like this to uniquely identify device. Retrieve running applications - see no reason for GPS tracking app to hold this. But maybe you use 3rd party lib/code that uses this.

How to show an Activity BEFORE my app is uninstalled (Android) [duplicate]

This question already has answers here:
Is it possible to detect Android app uninstall?
(8 answers)
Perform a task on uninstall in android [duplicate]
(4 answers)
Closed 7 years ago.
I though it was not possible but I noticed that NQ Mobile Security is able to show a message after I click on Uninstall and before the PackageUninstaller is called.
I would like to replicate this behavior in my App.
I tried with an Activity listening to "android.intent.action.DELETE" Intent, as suggested here:
How to know my app is uninstalled from the device...?
But as I'm about to uninstall my app, the chooser pops up asking to pick my application or the package uninstaller. How can I avoid this?
Is there a different way to intercept your application UNINSTALL event? (before answering that it is not possible, please try to uninstall NQ Mobile Security and see what happens. On my Android 2.3.4 it shows a nice screen saying that is not safe to go without a security app).

I noticed that NQ Mobile Security is able to show a message after I click on Uninstall and before the PackageUninstaller is called
They must be exploiting some security flaw in Android. I will research it and see if I can get it fixed. Apps are not supposed to get control at uninstall time.
Thanks for pointing this out!
Is there a different way to intercept your application UNINSTALL event?
I sure hope not.

Opera Max is an app that does something similar - after being uninstalled opens a webpage.
How do they do this?
By using libevent, from native code, they watch /data/data/com.opera.max directory to be removed and then post good old action.VIEW broadcast when it happens.
Install their app, run it, and on rooted device from adb shell remove /data/data/com.opera.max directory
UPDATE: I created a sample app that shows how it works. BTW it doesn't work with recent (KitKat+ I think) Android versions: https://github.com/pelotasplus/ActionAfterUninstall

I'm pretty sure that they are monitoring the LogCat to intercept when the Activity Manager calls the PackageUninstaller. I think they kill the task and start their own Activity.
It's pretty clever but it's definitely exploiting a security hole in Android.

They are likely asking for a very critical permission that the user is granting them unknowingly. Look at the "Permissions" tab for this app (as of 6/15/2012): https://play.google.com/store/apps/details?id=com.nqmobile.antivirus20&hl=en.
The list of permissions this app gets is downright chilling. Among other things:
SYSTEM TOOLS RETRIEVE RUNNING APPS Allows the app to retrieve
information about currently and recently running tasks. Malicious apps
may discover private information about other apps.
CHANGE/INTERCEPT NETWORK SETTINGS AND TRAFFIC Allows the app to change network settings
and to intercept and inspect all network traffic, for example to
change the proxy and port of any APN. Malicious apps may monitor,
redirect, or modify network packets without your knowledge.
PREVENT TABLET FROM SLEEPING PREVENT PHONE FROM SLEEPING Allows the app to
prevent the tablet from going to sleep. Allows the app to prevent the
phone from going to sleep.
CHANGE YOUR UI SETTINGS Allows the app to
change the current configuration, such as the locale or overall font
size.
MODIFY GLOBAL SYSTEM SETTINGS Allows the app to modify the
system's settings data. Malicious apps may corrupt your system's
configuration.
DISPLAY SYSTEM-LEVEL ALERTS Allows the app to show
system alert windows. Malicious apps may take over the entire screen.
MOUNT AND UNMOUNT FILESYSTEMS Allows the app to mount and unmount
filesystems for removable storage.
CHANGE NETWORK CONNECTIVITY Allows
the app to change the state of network connectivity.
CHANGE WI-FI STATE Allows the app to connect to and disconnect from Wi-Fi access
points, and to make changes to configured Wi-Fi networks.
-- Update --
I also found that the Android Package Manager pretty much just deletes a package if it is asked to do so. The only check it performs prior to doing so is whether the package being deleted is currently registered as having an active device admin:
try {
if (dpm != null && dpm.packageHasActiveAdmins(packageName)) {
Slog.w(TAG, "Not removing package " + packageName + ": has active device admin");
return PackageManager.DELETE_FAILED_DEVICE_POLICY_MANAGER;
}
} catch (RemoteException e) {
}
See line 6900 in PackageManagerService in the AOSP source here.
For this, the application must be explicitly registered as a device admin by the user. See notes on device administration here: http://developer.android.com/training/enterprise/device-management-policy.html.

As per https://stackoverflow.com/a/26829978/1317564, here is some example code that does it: https://github.com/zzljob/android-uninstall-feedback/blob/master/library/jni/feedback-uninstall.c. This won't actually stop the uninstall from taking place, but does provide a way to catch it and take some action. I'm honestly surprised that this works in Android and the team may have plugged the gap in recent releases.