The objective of this post is to learn how to create a virtualized work environment that allows us to start performing audits on Android applications. We will begin by selecting our device emulator, then show the different smartphone creation options, and finish with the download of some necessary tools for our work.
- Android Studio as the environment emulator
- Installation and first steps with Android Studio
- Installation and execution of Android Debug Bridge (ADB)
- References
Android Studio as the environment emulator
There are many free Android emulators that we can use for our testing environment, but it’s true that some of them stand out above the rest. After working with several of them, personally Android Studio is the one I like the most (basically, because it’s the one that has given me the least problems when performing audits). I acknowledge that it consumes more resources than other emulators and can be slower, but it has many more utilities and is more robust. You can download Android Studio through the following link:
Similarly, below I’ll leave you the download links for other Android emulators widely used by the community so you can try them and choose the one you like best, since we don’t all have the same tastes or the same criteria:
- Genymotion:
- BlueStacks:
- Visual Studio:
Installation and first steps with Android Studio
For the installation of our emulator, my recommendation is that it be installed on your computer’s main operating system, in my case Windows. You can also install it on a virtual machine with Kali or another distribution focused on pentesting, but the emulation of an Android device will require a lot of memory and you may have problems with the environment processing.
So, first of all, download Android Studio, run the installer, and follow the steps that appear during the process, leaving everything as default.
Once we have it installed, we’ll start it and see a window like the one shown below:
We’ll click on the More Actions dropdown and then select the Virtual Device Manager option to create our Android device:
IMPORTANT: It’s possible that this option may initially be blocked and we can’t select it. In that case, what we’ll do is select the SDK Manager option that is just above:
In this menu we need to make sure of two things:
- First, that the Android SDK Location path doesn’t appear in red because it doesn’t recognize the default predefined path, in which case we would have to choose a valid path ourselves.
- Second, that in the SDK Tools tab we have the Android SDK Build-Tools 33 package installed. If it’s not installed, we’ll click on the square that appears to the left of the name and click OK so it downloads and installs automatically:
Since I’m in this menu, I’ll take the opportunity to indicate that in the SDK Platforms section we can download the different Android versions that we’ll use on the devices we create later. They can also be downloaded from the device creation menu, so it’s not necessary to come to this window for that, but it’s good to know the different options available to perform the same tasks. I recommend taking a look and investigating the possible downloads:
Now yes, let’s proceed with the device creation in the new menu that has opened after selecting the Virtual Device Manager option.
This new window is empty, so we’ll click on Create Virtual Device which is in the center of it or on the Create device tab located in the upper left corner:
In the new pop-up window, different Hardware creation options appear, where we can choose different electronic devices. This is mainly so that developers can run and test their applications on the different devices that are capable of opening them.
We’re interested in the Phone tab, from which we can select among a series of available brands and see the respective characteristics of the different phones. Based on this, we’ll choose which one to emulate. It’s not necessary to choose a latest model because there may be problems later when running certain Android versions, nor a very old model for the inverse reason. Personally, I usually choose among the Nexus 5, Pixel 4, and Pixel 5 models. It’s important to note that in one of the columns you can see which devices include the Play Store for downloading applications, a function that may be necessary for obtaining the application to audit later:
When clicking on Next we’ll find the menu where we’ll choose the Android version we’re going to install on our smartphone. We find three different tabs indicating the recommended images, those that are x86, and other images. I don’t recommend installing the latest version of Android, nor a version that’s many years old, as both cases can generate problems when opening or running applications. I normally install those versions between 7 and 10, except for some specific cases where a specific version was necessary.
As I mentioned earlier, in this panel it will be possible to download the image we want to install by pressing the arrow that appears to the right of the version name. I’ve chosen an Android 8.0 (Google APIS) compatible with Google Play services and with an x86_64 architecture compatible with both 32 or 64-bit versions:
Once selected, we’ll find a final box where we can make some modifications to the configuration, but in principle the only thing we should touch is the name in case we want to identify it in some way. Once this is done, we finish:
Now, in the window that we previously found empty, the device will appear with information about the Android version and the architecture used. To run the emulator, we’ll click on the Play arrow that appears under the Actions column:
Once this is done, we now have our device running and ready to install and run any Android application compatible with its version and architecture.
Installation and execution of Android Debug Bridge (ADB)
Android Debug Bridge is a command-line tool that will allow us to communicate with the mobile device and execute multiple instructions to perform different actions, such as accessing the inside of the device, copying or deleting information, installing or uninstalling applications…
When downloading Android Studio, this tool is also included within the SDK Tools folder that we mentioned earlier under the name platform-tools. In any case, if you can’t find it, you can get it at the following link for download:
Once located or obtained, we’ll access that folder and open a cmd and run adb.exe to start the tool. Once this is done, within the same console, these are some of the main commands we can use:
- adb devices: Lists the emulators currently in the system.
- adb root/unroot: Restarts the client with/without root permissions (It’s important to note that for most actions it’s necessary to be root).
- adb push/pull [path_to_file]: Sends a file from the computer to the mobile device/from the mobile device to the computer.
- adb install/uninstall [path_to_apk]: Installs/uninstalls an application.
- adb shell: Allows access to the device via console (remember that Android is a Linux system, so the commands will be the same ones we use in our Kali).
- adb reboot: Forces a device reboot.
We now have the main scenario to start performing pentesting on Android applications. Soon, we’ll continue with a series of articles where we’ll see how to perform a complete audit of an Android application.