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Ganesh Tiwari

Android Reverse Engineering and Decompilation

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.

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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9 Comments on "Android Reverse Engineering and Decompilation"

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AtanasNeshkov
Guest

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
Guest

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
Guest

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
Guest

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

Manjunatha Reddy
Guest

How to retrieve native libraries from apk file.

Rocky
Guest

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

Saravana
Guest

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);

Andrew Rukin
Guest

There is new alternative: open-source APK and DEX decompiler called Jadx: https://sourceforge.net/projects/jadx/files/
It has online version here: http://www.javadecompilers.com/apk/

katrinahelen
Guest

Really nice post.Thanks for sharing.
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