Android Reverse Engineering and Decompilation

Ganesh TiwariNovember 2nd, 2012Last Updated: November 2nd, 2012

10 192 1 minute read

Reverse engineering of android java app using apktool, dex2jar, jd-gui to convert .apk file to .java.

By reverse engineering of android app (.apk file) we can get following :

understand how a particular UI in an App is constructed
reading AndroidManifest.xml – permissions, activities, intents etc in the App
native libraries and images used in that App
obsfucated code ( android SDK, by default, uses ProGuard tool which shrinks, optimizes, and obfuscates your code by removing unused code and renaming classes, fields, and methods with semantically obscure names.

Required Tools :

Download the followings first.

Dex2jar from http://code.google.com/p/dex2jar/
JD-GUI from http://java.decompiler.free.fr/?q=jdgui
ApkTool from http://code.google.com/p/android-apktool/

Using ApkTool

– to extract AndroidManifest.xml and everything in res folder(layout xml files, images, htmls used on webview etc..)

Run the following command :

>apktool.bat d sampleApp.apk

It also extracts the .smali file of all .class files, but which is difficult to read.

##You can achieve this by using zip utility like 7-zip.

Using dex2jar

– to generate .jar file from .apk file, we need JD-GUI to view the source code from this .jar.

Run the following command :

 >dex2jar sampleApp.apk

Decompiling .jar JD-GUI

– it decompiles the .class files (obsfucated- in case of android app, but readable original code is obtained in case of other .jar file). i.e., we get .java back from the application.

Just Run the

jd-gui.exe and File->Open to view java code from .jar or .class file.

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Reference: Android Reverse Engineering – decompile .apk-.dex-.jar-.java from our JCG partner Ganesh Tiwari at the GT’s Blog blog.

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Ganesh TiwariNovember 2nd, 2012Last Updated: November 2nd, 2012

10 192 1 minute read

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AtanasNeshkov

11 years ago

With AndroChef Java Decompiler you can decompile apk., dex, jar and java class-files. It’s simple and easy. http://www.androiddecompiler.com/

Freeman Mobile

This way is just fine!
But JD-GUI homepage has changed!
Follow this tutorial to get updated link of JD-GUI
How to decompile Android APK file

Venkatesan

10 years ago

Hi,

I am very much eager to become a very good Android Development Engineer.I need one help from you.Currently I am having Source files,fully layout file and a manifest file.Will u go through it and compile it and help me.This project will help me out to become a very good Android Engineer.please help me.

Thanks and Regards,
Venkatesan.R

Hey Ganesh

Is is possible to get native libraries using APK file, Thank you!

Manjunatha Reddy

How to retrieve native libraries from apk file.

Rocky

9 years ago

Hi,
Is this is possible to read data from a server using modbus protocol. ?

Saravana

After decompileing the class file to java file in the setContentView the layout name to some 10 digit number how can I find the correct layout with that class. Is there any way to find out.

E.g:
setContentView (1234567890);