APK decompilers
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For further details on each tool check the original post from https://eiken.dev/blog/2021/02/how-to-break-your-jar-in-2021-decompilation-guide-for-jars-and-apks/#cfr
As the pioneering GUI Java decompiler, JD-Gui allows you to investigate Java code within APK files. It's straightforward to use; after obtaining the APK, simply open it with JD-Gui to inspect the code.
Jadx offers a user-friendly interface for decompiling Java code from Android applications. It's recommended for its ease of use across different platforms.
To launch the GUI, navigate to the bin directory and execute:
jadx-guiFor command-line usage, decompile an APK with:
jadx app.apkTo specify an output directory or adjust decompilation options:
jadx app.apk -d <path to output dir> --no-res --no-src --no-imports
GDA, a Windows-only tool, offers extensive features for reverse engineering Android apps. Install and run GDA on your Windows system, then load the APK file for analysis.
With Bytecode-Viewer, you can analyze APK files using multiple decompilers. After downloading, run Bytecode-Viewer, load your APK, and select the decompilers you wish to use for simultaneous analysis.
Enjarify translates Dalvik bytecode to Java bytecode, enabling Java analysis tools to analyze Android applications more effectively.
To use Enjarify, run:
enjarify app.apkThis generates the Java bytecode equivalent of the provided APK.
CFR is capable of decompiling modern Java features. Use it as follows:
For standard decompilation:
java -jar ./cfr.jar "app.jar" --outputdir "output_directory"For large JAR files, adjust the JVM memory allocation:
java -Xmx4G -jar ./cfr.jar "app.jar" --outputdir "output_directory"
Fernflower, an analytical decompiler, requires building from source. After building:
Decompile a JAR file:
java -jar ./fernflower.jar "app.jar" "output_directory"Then, extract the.javafiles from the generated JAR usingunzip.
Krakatau offers detailed control over decompilation, especially for handling external libraries.
Use Krakatau by specifying the standard library path and the JAR file to decompile:
./Krakatau/decompile.py -out "output_directory" -skip -nauto -path "./jrt-extractor/rt.jar" "app.jar"
For straightforward decompilation with procyon:
Decompile a JAR file to a specified directory:
procyon -jar "app.jar" -o "output_directory"
This tool can be used to dump the DEX of a running APK in memory. This helps to beat static obfuscation that is removed while the application is executed in memory.
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