Jon Douglas The rantings of a developer

APK Tools

15 Mar 2017

APK Tools

I’ve found many APK tools to be quite useful for diagnosing issues with Xamarin.Android. Here is a small list of tools that I find helpful.

apktool

apktool is a tool for reverse engineering Android applications. It can be used to decode resources to nearly original form and rebuild them after making some modifications.

Decode

One of the most useful usecases of apktool is to ensure your generated .apk is correct. You can use the decode / d method to take an .apk and “unzip” it’s original contents.

usage: apktool d MyApplication.apk

Build

The other usecase is to build a .apk after making a couple of modifications. You can use the build / b method to build an .apk

usage: apktool b foo

Which will build a folder named foo into an .apk file.

Note: If you aren’t using the wrapper script, you may need to invoke it via java -jar apktool.jar

aapt

aapt provides a couple of useful tools for our .apk files. You can find aapt inside of your Android SDK’s build-tools folder.

list

aapt list - shows the contents of the package.

usage: aapt list MyApplication.apk

META-INF/MANIFEST.MF
META-INF/ANDROIDD.SF
META-INF/ANDROIDD.RSA
AndroidManifest.xml
res/drawable/icon.png
res/layout/main.xml
resources.arsc
NOTICE
classes.dex
assemblies/MyApplication.dll
assemblies/Java.Interop.dll
assemblies/Microsoft.CSharp.dll
assemblies/Mono.Android.dll
assemblies/mscorlib.dll
assemblies/System.Core.dll
assemblies/System.dll
assemblies/System.Xml.dll
assemblies/System.Threading.dll
assemblies/System.Runtime.dll
assemblies/System.Collections.dll
assemblies/System.Collections.Concurrent.dll
assemblies/System.Diagnostics.Debug.dll
assemblies/System.Reflection.dll
assemblies/System.Linq.dll
assemblies/System.Runtime.InteropServices.dll
assemblies/System.Runtime.Extensions.dll
assemblies/System.Reflection.Extensions.dll
assemblies/Mono.CSharp.dll
assemblies/System.Runtime.Serialization.dll
environment
lib/armeabi-v7a/libmonodroid.so
lib/armeabi-v7a/libmonosgen-2.0.so
typemap.jm
typemap.mj

dump

aapt dump - provides values of individual elements or parts of a package. There are a few different items we can dump:

badging - dumps badging information like the versions, sdk targets, etc

usage: aapt dump badging MyApplication.apk

package: name='MyApplication.MyApplication' versionCode='1' versionName='1.0' platformBuildVersionName='7.1.1'
sdkVersion:'16'
application-icon-160:'res/drawable/icon.png'
application: label='' icon='res/drawable/icon.png'
launchable-activity: name='md5ef8aabbe49b48f4362a43abcfb4dce14.MainActivity'  label='MyApplication' icon='res/drawable/icon.png'
feature-group: label=''
  uses-feature: name='android.hardware.faketouch'
  uses-implied-feature: name='android.hardware.faketouch' reason='default feature for all apps'
main
supports-screens: 'small' 'normal' 'large' 'xlarge'
supports-any-density: 'true'
locales:
densities: '160'
native-code: 'armeabi-v7a'

permissions - dumps permission information such as what uses-permissions are in use

usage: aapt dump permissions MyApplication.apk

package: MyApplication.MyApplication
uses-permission: name='android.permission.INTERNET'
uses-permission: name='android.permission.READ_CALENDAR'
uses-permission: name='android.permission.READ_CONTACTS'

resources - dumps resources in each resource category such as string/array/layout/etc

usage: aapt dump resources MyApplication.apk

Package Groups (1)
Package Group 0 id=0x7f packageCount=1 name=MyApplication.MyApplication
  Package 0 id=0x7f name=MyApplication.MyApplication
    type 1 configCount=1 entryCount=1
      spec resource 0x7f020000 MyApplication.MyApplication:drawable/icon: flags=0x00000000
      config (default):
        resource 0x7f020000 MyApplication.MyApplication:drawable/icon: t=0x03 d=0x00000000 (s=0x0008 r=0x00)
    type 2 configCount=1 entryCount=1
      spec resource 0x7f030000 MyApplication.MyApplication:layout/main: flags=0x00000000
      config (default):
        resource 0x7f030000 MyApplication.MyApplication:layout/main: t=0x03 d=0x00000001 (s=0x0008 r=0x00)
    type 3 configCount=1 entryCount=2
      spec resource 0x7f040000 MyApplication.MyApplication:string/Hello: flags=0x00000000
      spec resource 0x7f040001 MyApplication.MyApplication:string/ApplicationName: flags=0x00000000
      config (default):
        resource 0x7f040000 MyApplication.MyApplication:string/Hello: t=0x03 d=0x00000002 (s=0x0008 r=0x00)
        resource 0x7f040001 MyApplication.MyApplication:string/ApplicationName: t=0x03 d=0x00000003 (s=0x0008 r=0x00)

configurations - dumps any configuration that has been setup

usage: aapt dump configurations MyApplication.apk

imsi=0/0 lang=-- reg=-- orient=0 touch=0 dens=160 kbd=0 nav=0 input=0 scrnW=0 scrnH=0 sz=0 long=0 vers=0.0
imsi=0/0 lang=-- reg=-- orient=0 touch=0 dens=240 kbd=0 nav=0 input=0 scrnW=0 scrnH=0 sz=0 long=0 vers=0.0
imsi=0/0 lang=-- reg=-- orient=0 touch=0 dens=0 kbd=0 nav=0 input=0 scrnW=0 scrnH=0 sz=0 long=0 vers=0.0

xmltree - dumps the xml parse tree for an xml file in a package

usage: aapt dump xmltree MyApplication.apk res/layout/main.xml

N: android=http://schemas.android.com/apk/res/android
  E: LinearLayout (line=1)
    A: android:orientation(0x010100c4)=(type 0x10)0x1
    A: android:layout_width(0x010100f4)=(type 0x10)0xffffffff
    A: android:layout_height(0x010100f5)=(type 0x10)0xffffffff

xmlstrings - dumps all strings inside for an xml file in a package

usage: aapt dump xmlstrings MyApplication.apk res/layout/main.xml

String pool of 7 unique UTF-8 non-sorted strings, 7 entries and 0 styles using 176 bytes:
String #0: orientation
String #1: layout_width
String #2: layout_height
String #3: android
String #4: http://schemas.android.com/apk/res/android
String #5:
String #6: LinearLayout

ClassyShark

ClassyShark is a binary inspection tool that can help you find information such as your total dex count, decompilation of .class files, and much more. It supports .dex, .aar, .so, .apk, .jar, .class, .xml files for further inspection.

usage: java -jar classyshark.jar

You should see a program like the following:

You can then inspect any aspect of your binary such as decompiling a class, viewing what’s inside of a dex file, and much more.

Classes

You can view what’s inside of your main dex list. Also known as the classes.dex file that is generated in the Android build process.

Methods Count

You can also see the current method count of the classes.dex list from an overview

Summary

Although this blog post only showcases 3 tools, there are so many ways to get information from your binaries to diagnose issues such as multidex, versioning, etc in you Xamarin.Android application!

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