Android_Emuroot

Introduction

Android_Emuroot is a Python script that allows granting root privileges on the fly to shells running on Android virtual machines that use google-provided emulator images called Google API Playstore, to help reverse engineers to go deeper into their investigations.

Android_Emuroot requires the Google API Playstore emulator to be launched with the qemu gdb stub option enabled, and uses it to alter process metadata stored in memory in kernel task structures. The main idea is to start from a shell with the lowest privileges, then to find its associated credential structure in kernel memory to replace it by another structure having the highest privileges.

Implementing this memory modification on a Google API Playstore emulator presents the following two advantages:

to work with an environment very similar to a physical device (with production build number, etc.) and with all Google Play and Google services packages already installed. This is often required by the targeted applications
to have a very easily modifiable memory since a GDB debugger can be attached to the device to fully control the kernel memory

Requirements

Prerequisites

Android_Emuroot requires to already have a working Android SDK. Installing the command-line tools is recommended (downloadable via the Android Studio GUI: Tools > Android > SDK manager > SDK Tools).

Installing dependencies

Android_Emuroot is a Python script that uses the ADB facilities as well as the GDB facilities from the two following Python's modules:

pygdbmi (Parse GDB machine interface output with Python)
pure-python-adb (Pure Python implementation of the ADB client)

Be sure you have these modules or install them via pip: pip3 install -r requirements.txt.

N.B.: Android_Emuroot supports Python 2 and Python 3.

Supported Google API Playstore emulators

Depending on the hardware architecture and the kernel version of the emulator, the memory layout of the related qemu image varies. Thereby the location of the memory patches implemented by Android_Emuroot varies as well.

For now, Android_Emuroot supports the following versions of emulators:

Android version	API	Architecture	Kernel	Build
Android 7.0	24	x86	3.10	google-api-playstore
Android 7.1.1	25	x86	3.10	google-api-playstore
Android 8.0	26	x86	3.18	google-api-playstore
Android 8.1	27	x86	3.18	google-api-playstore

Be sure the AVD you want to root is based on one emulator of this list.

N.B.: the emulators can be downloaded via sdkmanager, a tool from the Android Studio toolchain, with the GUI or in command line, for example like this: sdkmanager --install "system-images;android-27;google_apis_playstore;x86". Then, create an Android Virtual Device (AVD) accordingly, via the AVD manager GUI or with avdmanager like this: avdmanager create avd -n my_avd_name -k "system-images;android-27;google_apis_playstore;x86".

Working environment

Android_Emuroot needs to interact with both:

the ADB server of to get information from the emulated device and spawn shells inside
the GDB server of QEMU to get information about the memory layout of the emulated device and patch values in memory

The scheme below shows the interactions between all the elements:

Android_Emuroot working environment

Launching the ADB server

The Android Debug Bridge (ADB) is a command line tool of the Android Studio toolchain that lets communicate with an Android device. The ADB server is the component that manages communication between Android_Emuroot and the ADB daemon launched on the device. By default, ADB servers listen on 127.0.0.1 port 5037. adb start-server lets you ensure that there is a server running.

Be sure your ADB server is running.

Running the emulator with a GDB server

The other requirement to use Android_Emuroot is to attach a GDB server to your AVD when launching it. emulator, another command line tool of the Android Studio toolchain, allows to launch AVDs with a lot of options. Among them: -qemu -s (shorthang for -qemu -gdb tcp::1234) which opens a GDB server on TCP port 1234.

Use this option to get a GDB server available.

Here is an simple example of emulator's usage:

emulator -avd my_avd_name [options] -qemu -s

This way, a GDB server will be attached to the AVD my_avd_name and Android_Emuroot will be able to spawn its GDB client and perform the memory patches.

Once both ADB server and GDB server are operational, you are ready to use Android_Emuroot.

Usage

Features

Android_Emuroot has 3 modes:

single --magic-name NAME: to give root privileges to only 1 shell given in parameter
adbd [--stealth]: to give root privileges to the entire adbd server; each new shell will be spawned as root
setuid --path NAME: to install a setuid root binary on the file system

More details on the usage and the tool internals: Detailed Usage

About

Authors

Android_Emuroot has been written by Mouad Abouhali and Anaïs Gantet from airbus-seclab.

License

Android_Emuroot is released under GPLv2.