decompile

Hi! 🙂 Here another way of decompiling an android apk file. This method does not directly decompile the source. First uses the tool “Dex2jar” to convert the classes.dex file in to a compressed jar file containing the .class files . Later the “jd-gui” decompiler can be used to decompile the jar file content to the original source. Following figure shows the process of compiling android source into an apk and the reverse engineering flow.

Convert the dex file to a jar with “dex2jar”

Download the latest “dex2jar” from –> (https://sourceforge.net/projects/dex2jar/files)

Unzip the file . The d2j-dex2jar.sh file in the dex2jar-2.0 diectory is used to generate the jar file.

Make the .d2j-invoke.sh file executable. Otherwise you will get permission denied message.

Command $ sudo chmod +x d2j-invoke.sh

Goto the dex2-jar foler –>Execute the following command to generate the jar file. This will create something like classes-dex.jar

This is the classes.dex file that I am using in the example.

Command $ sh d2j-dex2jar.sh <path to classes.dex file>

you can simply drag and drop the classes.dex file to the terminal so that it will take the path automatically.

The resulted classes-dex2jar.jar file will be generated in the same location.

You can unzip the jar file and see that it contains .class files

Decompile the original source with “JD-GUI” decompiler

Download the “jd-gui” for linux from -> (http://jd.benow.ca/)

Unzip the file and you will see “jd-gui” executable file.

If you are having 64 bit Ubuntu 14.0 then install following libs

Command $ sudo apt-get install libgtk2.0-0:i386 libxxf86vm1:i386 libsm6:i386 lib32stdc++6

Now run the “jd-gui”. It will open the decompiler

Open the generated classes-dex2jar.jar file from the decompiler. You will be able to view the original source from this.

Cheers ! 🙂

Hi ! 🙂 “Apktool” is another reverse engineering tool specifically designed to decode, edit, analyse and rebuild android apk files. Here I will state the steps to installing Apktool version 2.0 on ubuntu 14.0. With the migration of Apktool to its version 2.0, some settings have reduced. According to the documentation of “Apktool” now it doesn’t required to add aapt separately, since it is included in the the apktool itself.

The default framework included in the Apktool is enough to decode most apk files except the manufacture apks, since they require additional framework-res specific for the manufacture.

Setting up APKTool

Download apktool.jar and apktool wrapper script for Linux environment from their official web site -> http://ibotpeaches.github.io/Apktool/install/ .

Change the owner of the files to your username of home directory.

This is required to allow access to the files.

Command $ chown -R username:username apktool.jar

Command $ chown -R username:username apktool

Change permission to allow executing the files

Command $ sudo chmod +x apktool.jar

Command $ sudo chmod +x apktool

Move the files to usr/local/bin

Command $ sudo mv apktool.jar /usr/local/bin

Command $ sudo mv apktool /usr/local/bin

Now you can run apktool commands from any directory.

Open a new terminal and execute apktool, you can see the help menu. Confirms the installation.

Command $ apktool

Now the environment is ready. So let’s try decompiling and rebuilding an random apk.

Decompiling …

Command $: apktool d <any.apk>

Ex.

Command $: apktool d PlayStore_v5.3.5.apk

The playstore apk is decompiled in to a new folder in the same directory.

The decompiled files include all the source files and resource files. The resource files are suffixed with .smali.

Rebuilding…

When you rebuild the resulted decompiled source files, two new folders will be created at the same location.

dist foler –> contains the rebuild apk file

Getting Framework-res

Before start decompiling any apk, find the available framework-res for the decompile to be properly happend.

Ex.

If your device is rooted, then you can pull out the available framework-res files.

Check for the available res files with following command.

Command $ adb shell

Command $ pm list packages -f

Pull out any available framework res files.

Command $ adb pull /system/framework/framework-res.apk

Note:

When your are trying to disassemble manufacture apks for instance Settings.apk, Contacts.apk, Maps.apk etc. you need to have proper framework resource. If that is not then you won’t be able to do the decoding properly.

Ex: When trying to decompile Maps.apk it says “Can’f find framework resources for package of id:2”