# AVD - Android Virtual Device

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`

## JDK

For MacOS machines I recommend you to install the following version to be able to use the CLI commands mentioned in the following sections:

```bash
brew install openjdk@8
```

## GUI

### Prepare Virtual Machine

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

![](../../.gitbook/assets/image%20%28366%29.png)

Then, click on _**Create Virtual Device**_, _**select** the phone you want to use_ and click on _**Next.**_  
In the current view you are going to be able to **select and download the Android image** that the phone is going to run:

![](../../.gitbook/assets/image%20%28369%29.png)

So, select it and click on _**Download**_ **\(**now wait until the image is downloaded\).  
Once the image is downloaded, just select _**Next**_ and _**Finish**_.

![](../../.gitbook/assets/image%20%28361%29.png)

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**_.

![](../../.gitbook/assets/image%20%28364%29.png)

## Command Line tool

### Prepare Virtual Machine

{% hint style="info" %}
In **MacOS** systems the executable is located in `/Users/<username>/Library/Android/sdk/tools/bin`
{% endhint %}

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

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

id: 0 or "tv_1080p"
    Name: Android TV (1080p)
    OEM : Google
    Tag : android-tv
---------
id: 1 or "tv_720p"
    Name: Android TV (720p)
    OEM : Google
    Tag : android-tv
---------
id: 2 or "wear_round"
    Name: Android Wear Round
    OEM : Google
    Tag : android-wear
---------
id: 3 or "wear_round_chin_320_290"
    Name: Android Wear Round Chin
    OEM : Google
    Tag : android-wear
---------
id: 4 or "wear_square"
    Name: Android Wear Square
    OEM : Google
    Tag : android-wear
---------
id: 5 or "Galaxy Nexus"
    Name: Galaxy Nexus
    OEM : Google
---------
id: 6 or "Nexus 10"
    Name: Nexus 10
    OEM : Google
---------
id: 7 or "Nexus 4"
    Name: Nexus 4
    OEM : Google
---------
id: 8 or "Nexus 5"
    Name: Nexus 5
    OEM : Google
---------
id: 9 or "Nexus 5X"
    Name: Nexus 5X
    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:

```text
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

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 \(very useful to capture the traffic using Burp\)
* `-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.

## Install Burp certificate on a Virtual Machine

First of all you need to download the Der certificate from Burp. You can do this in _**Proxy**_ --&gt; _**Options**_ --&gt; _**Import / Export CA certificate**_

![](../../.gitbook/assets/image%20%28367%29%20%281%29.png)

**Export the certificate in Der format** and lets **transform** it to a form that **Android** is going to be able to **understand.** Note that **in order to configure the burp certificate on the Android machine in AVD** you need to **run** this machine **with** the **`-writable-system`** option.  
For example you can run it like:

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

Then, to **configure burps certificate do**:

```bash
openssl x509 -inform DER -in burp_cacert.der -out burp_cacert.pem
CERTHASHNAME="`openssl x509 -inform PEM -subject_hash_old -in burp_cacert.pem | head -1`.0"
mv burp_cacert.pem $CERTHASHNAME #Correct name
adb root && adb remount #Allow to write on /syste
adb push $CERTHASHNAME /sdcard/ #Upload certificate
adb shell mv /sdcard/$CERTHASHNAME /system/etc/security/cacerts/ #Move to correct location
adb shell chmod 644 /system/etc/security/cacerts/$CERTHASHNAME #Assign privileges
adb reboot #Now, reboot the machine
```

Once the **machine finish rebooting** the burp certificate will be in use by it!

## Take a Snapshot

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

![](../../.gitbook/assets/image%20%28363%29.png)