hacktricks/src/mobile-pentesting/android-app-pentesting/avd-android-virtual-device.md

# AVD - Android Virtual Device

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Thank you very much to [**@offsecjay**](https://twitter.com/offsecjay) for his help while creating this content.

## What is

Android Studio allows to **run virtual machines of Android that you can use to test APKs**. In order to use them you will need:

- The **Android SDK tools** - [Download here](https://developer.android.com/studio/releases/sdk-tools).
- Or **Android Studio** (with Android SDK tools) - [Download here](https://developer.android.com/studio).

In Windows (in my case) **after installing Android Studio** I had the **SDK Tools installed in**: `C:\Users\<UserName>\AppData\Local\Android\Sdk\tools`

In mac you can **download the SDK tools** and have them in the PATH running:

```bash
brew tap homebrew/cask
brew install --cask android-sdk
```

Or from **Android Studio GUI** as indicated in [https://stackoverflow.com/questions/46402772/failed-to-install-android-sdk-java-lang-noclassdeffounderror-javax-xml-bind-a](https://stackoverflow.com/questions/46402772/failed-to-install-android-sdk-java-lang-noclassdeffounderror-javax-xml-bind-a) which will install them in `~/Library/Android/sdk/cmdline-tools/latest/bin/` and `~/Library/Android/sdk/platform-tools/` and `~/Library/Android/sdk/emulator/`

For the Java problems:

```java
export JAVA_HOME=/Applications/Android\ Studio.app/Contents/jbr/Contents/Home
```

## GUI

### Prepare Virtual Machine

If you installed Android Studio, you can just open the main project view and access: _**Tools**_ --> _**AVD Manager.**_

<div align="center" data-full-width="false">

<figure><img src="../../images/image (1142).png" alt="" width="293"><figcaption></figcaption></figure>

</div>

Then, click on _**Create Virtual Device**_

<figure><img src="../../images/image (1143).png" alt="" width="188"><figcaption></figcaption></figure>

_**select** the phone you want to use_ and click on _**Next.**_

> [!WARNING]
> If you need a phone with Play Store installed select one with the Play Store icon on it!
>
> <img src="../../images/image (1144).png" alt="" data-size="original">

In the current view you are going to be able to **select and download the Android image** that the phone is going to run:

<figure><img src="../../images/image (1145).png" alt="" width="375"><figcaption></figcaption></figure>

So, select it and if it isn't downloaded click on the _**Download**_ symbol next to the name (**now wait until the image is downloaded).**\
Once the image is downloaded, just select **`Next`** and **`Finish`**.

The virtual machine will be created. Now **every time that you access AVD manager it will be present**.

### Run Virtual Machine

In order to **run** it just press the _**Start button**_.

![](<../../images/image (518).png>)

## Command Line tool

> [!WARNING]
> For macOS you can find the `avdmanager` tool in `/Users/<username>/Library/Android/sdk/tools/bin/avdmanager` and the `emulator` in `/Users/<username>/Library/Android/sdk/emulator/emulator` if you have them installed.

First of all you need to **decide which phone you want to use**, in order to see the list of possible phones execute:

```
C:\Users\<UserName>\AppData\Local\Android\Sdk\tools\bin\avdmanager.bat list device

d: 0 or "automotive_1024p_landscape"
    Name: Automotive (1024p landscape)
    OEM : Google
    Tag : android-automotive-playstore
---------
id: 1 or "Galaxy Nexus"
    Name: Galaxy Nexus
    OEM : Google
---------
id: 2 or "desktop_large"
    Name: Large Desktop
    OEM : Google
    Tag : android-desktop
---------
id: 3 or "desktop_medium"
    Name: Medium Desktop
    OEM : Google
    Tag : android-desktop
---------
id: 4 or "Nexus 10"
    Name: Nexus 10
    OEM : Google
[...]
```

Once you have decide the name of the device you want to use, you need to **decide which Android image you want to run in this device.**\
You can list all the options using `sdkmanager`:

```bash
C:\Users\<UserName>\AppData\Local\Android\Sdk\tools\bin\sdkmanager.bat --list
```

And **download** the one (or all) you want to use with:

```bash
C:\Users\<UserName>\AppData\Local\Android\Sdk\tools\bin\sdkmanager.bat "platforms;android-28" "system-images;android-28;google_apis;x86_64"
```

Once you have downloaded the Android image you want to use you can **list all the downloaded Android images** with:

```
C:\Users\<UserName>\AppData\Local\Android\Sdk\tools\bin\avdmanager.bat list target
----------
id: 1 or "android-28"
     Name: Android API 28
     Type: Platform
     API level: 28
     Revision: 6
----------
id: 2 or "android-29"
     Name: Android API 29
     Type: Platform
     API level: 29
     Revision: 4
```

At this moment you have decided the device you want to use and you have downloaded the Android image, so **you can create the virtual machine using**:

```bash
C:\Users\<UserName>\AppData\Local\Android\Sdk\tools\bin\avdmanager.bat -v create avd -k "system-images;android-28;google_apis;x86_64" -n "AVD9" -d "Nexus 5X"
```

In the last command **I created a VM named** "_AVD9_" using the **device** "_Nexus 5X_" and the **Android image** "_system-images;android-28;google_apis;x86_64_".\
Now you can **list the virtual machines** you have created with:

```bash
C:\Users\<UserName>\AppData\Local\Android\Sdk\tools\bin\avdmanager.bat list avd

 Name: AVD9
  Device: Nexus 5X (Google)
    Path: C:\Users\cpolo\.android\avd\AVD9.avd
  Target: Google APIs (Google Inc.)
          Based on: Android API 28 Tag/ABI: google_apis/x86_64

The following Android Virtual Devices could not be loaded:
    Name: Pixel_2_API_27
    Path: C:\Users\cpolo\.android\avd\Pixel_2_API_27_1.avd
   Error: Google pixel_2 no longer exists as a device
```

### Run Virtual Machine

> [!WARNING]
> For macOS you can find the `avdmanager` tool in `/Users/<username>/Library/Android/sdk/tools/bin/avdmanager` and the `emulator` in `/Users/<username>/Library/Android/sdk/emulator/emulator` if you have them installed.

We have already seen how you can list the created virtual machines, but **you can also list them using**:

```bash
C:\Users\<UserName>\AppData\Local\Android\Sdk\tools\emulator.exe -list-avds
AVD9
Pixel_2_API_27
```

You can simply **run any virtual machine created** using:

```bash
C:\Users\<UserName>\AppData\Local\Android\Sdk\tools\emulator.exe -avd "VirtualMachineName"
C:\Users\<UserName>\AppData\Local\Android\Sdk\tools\emulator.exe -avd "AVD9"
```

Or using more advance options you can run a virtual machine like:

```bash
C:\Users\<UserName>\AppData\Local\Android\Sdk\tools\emulator.exe -avd "AVD9" -http-proxy 192.168.1.12:8080 -writable-system
```

### Command line options

However there are **a lot of different command line useful options** that you can use to initiate a virtual machine. Below you can find some interesting options but can [**find a complete list here**](https://developer.android.com/studio/run/emulator-commandline)

**Boot**

- `-snapshot name` : Start VM snapshot
- `-snapshot-list -snapstorage ~/.android/avd/Nexus_5X_API_23.avd/snapshots-test.img` : List all the snapshots recorded

**Network**

- `-dns-server 192.0.2.0, 192.0.2.255` : Allow to indicate comma separated the DNS servers to the VM.
- **`-http-proxy 192.168.1.12:8080`** : Allow to indicate an HTTP proxy to use (very useful to capture the traffic using Burp)
    - If the proxy settings aren't working for some reason, try to configure them internally or using an pplication like "Super Proxy" or "ProxyDroid".
- `-netdelay 200` : Set the network latency emulation in milliseconds.
- `-port 5556` : Set the TCP port number that's used for the console and adb.
- `-ports 5556,5559` : Set the TCP ports used for the console and adb.
- **`-tcpdump /path/dumpfile.cap`** : Capture all the traffic in a file

**System**

- `-selinux {disabled|permissive}` : Set the Security-Enhanced Linux security module to either disabled or permissive mode on a Linux operating system.
- `-timezone Europe/Paris` : Set the timezone for the virtual device
- `-screen {touch(default)|multi-touch|o-touch}` : Set emulated touch screen mode.
- **`-writable-system`** : Use this option to have a writable system image during your emulation session. You will need also to run `adb root; adb remount`. This is very useful to install a new certificate in the system.

## Linux CLI setup (SDK/AVD quickstart)

The official CLI tools make it easy to create fast, debuggable emulators without Android Studio.

```bash
# Directory layout
mkdir -p ~/Android/cmdline-tools/latest

# Download commandline tools (Linux)
wget https://dl.google.com/android/repository/commandlinetools-linux-13114758_latest.zip -O /tmp/cmdline-tools.zip
unzip /tmp/cmdline-tools.zip -d ~/Android/cmdline-tools/latest
rm /tmp/cmdline-tools.zip

# Env vars (add to ~/.bashrc or ~/.zshrc)
export ANDROID_HOME=$HOME/Android
export PATH=$ANDROID_HOME/cmdline-tools/latest/bin:$ANDROID_HOME/platform-tools:$ANDROID_HOME/emulator:$PATH

# Install core SDK components
sdkmanager --install "platform-tools" "emulator"

# Install a debuggable x86_64 system image (Android 11 / API 30)
sdkmanager --install "system-images;android-30;google_apis;x86_64"

# Create an AVD and run it with a writable /system & snapshot name
avdmanager create avd -n PixelRootX86 -k "system-images;android-30;google_apis;x86_64" -d "pixel"
emulator -avd PixelRootX86 -writable-system -snapshot PixelRootX86_snap

# Verify root (debuggable images allow `adb root`)
adb root
adb shell whoami  # expect: root
```

Notes
- System image flavors: google_apis (debuggable, allows adb root), google_apis_playstore (not rootable), aosp/default (lightweight).
- Build types: userdebug often allows `adb root` on debug-capable images. Play Store images are production builds and block root.
- On x86_64 hosts, full-system ARM64 emulation is unsupported from API 28+. For Android 11+ use Google APIs/Play images that include per-app ARM-to-x86 translation to run many ARM-only apps quickly.

### Snapshots from CLI

```bash
# Save a clean snapshot from the running emulator
adb -s emulator-5554 emu avd snapshot save my_clean_setup

# Boot from a named snapshot (if it exists)
emulator -avd PixelRootX86 -writable-system -snapshot my_clean_setup
```

## ARM→x86 binary translation (Android 11+)

Google APIs and Play Store images on Android 11+ can translate ARM app binaries per process while keeping the rest of the system native x86/x86_64. This is often fast enough to test many ARM-only apps on desktop.

> Tip: Prefer Google APIs x86/x86_64 images during pentests. Play images are convenient but block `adb root`; use them only when you specifically require Play services and accept the lack of root.

## Rooting a Play Store device

If you downloaded a device with Play Store you are not going to be able to get root directly, and you will get this error message

```
$ adb root
adbd cannot run as root in production builds
```

Using [rootAVD](https://github.com/newbit1/rootAVD) with [Magisk](https://github.com/topjohnwu/Magisk) I was able to root it (follow for example [**this video**](https://www.youtube.com/watch?v=Wk0ixxmkzAI) **or** [**this one**](https://www.youtube.com/watch?v=qQicUW0svB8)).

## Install Burp Certificate

Check the following page to learn how to install a custom CA cert:


{{#ref}}
install-burp-certificate.md
{{#endref}}

## Nice AVD Options

### Take a Snapshot

You can **use the GUI** to take a snapshot of the VM at any time:

![](<../../images/image (234).png>)

## References

- [Build a Repeatable Android Bug Bounty Lab: Emulator vs Magisk, Burp, Frida, and Medusa](https://www.yeswehack.com/learn-bug-bounty/android-lab-mobile-hacking-tools)
- [Android Emulator command line](https://developer.android.com/studio/run/emulator-commandline)
- [Run ARM apps on the Android Emulator (x86 translation)](https://android-developers.googleblog.com/2020/03/run-arm-apps-on-android-emulator.html)

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