Skip to main content


Showing posts from April, 2014

Reverse Engineering : Convert class or jar to Java files

Previously, we have seen how to extract contents of .img file and also how to convert dex files to classes/jar . In this post, I'm going to show a method to covert class/classes/jar file to java file(s). To do so, we are going to use a tool, JD-GUI. It is a Java Decompiler, which supports all versions of Java, including java-7. Download the application from here , and extract it to a proper location. Now, open the terminal (in case of Linux) and run the following command: ./jd-gui It will open the GUI window of Java decompiler. Just drag-and-drop a class/jar file into this window. In the left panel, we can find the corresponding java files, arranged in proper package format. To save a single file, select it and choose "Save Source" from the top menu. And to save entire package, choose "Save all sources". Troubleshooting : You may ran into one of these problems, while trying to open jd-gui. Install the packages specified accordingly. Erro

Reverse Engineering : Android Dex files to Class files

In my previous post, we have seen how to extract the contents of img file . After extraction, you will find that most of the files have ".dex" extension. These are Compiled Android application code files. In order to convert them into executable format (.class or .jar), you can use dex2jar tool. Extract it to a proper location and open the terminal to this location. Now run the following command: ./ <Path-to-dex_file> It will bundle the dex files into a jar file, and stores it in the current directory. dex2jar can also be used to convert dex files into variuos other formats. For detailed info, click here .

Reverse Engineering : Extract contents from .img file

Unyaffs is a program to extract files from a YAFFS2 file system image. Currently it can only extract images created by mkyaffs2image. Download the source from here . Compiling : Extract the contents into a suitable place and run the following command make Usage : unyaffs [options] <image_file_name> [<extract_directory>] Options: -d detection of flash layout, no extraction -b spare contains bad block information -c <chunk size> set chunk size in KByte (default: autodetect, max: 16) -s <spare size> set spare size in Byte (default: autodetect, max: 512) -t list image contents -v verbose output -V print version Source: Official github repository

Ubuntu: Problem installing flash player

Recently, I installed ubuntu updates and my browser asked me for flash player, which was previously installed. i tried to install using the regular command sudo apt-get install flashplugin-installer But, it says flashplugin-installer is already the newest version Finally, I found the workaround. Previous installation has to removed first (which anyway is not working) Run the following commands : sudo apt-get purge flashplugin-installer sudo apt-get install flashplugin-installer Viola!! It works now.


Today, I tried to install an application from command line and I found this error: Failure [INSTALL_FAILED_UID_CHANGED] After Googling for a while, I found the reason. This happens when there is application data from older version is still present. To resolve this, clear/delete the following directory: /data/data/<PACKAGE_NAME> To do this, open terminal and type the following commands: adb shell cd /data/data/ rm -r <PACKAGE_NAME> exit Now try to install the application. Viola.