Book Image

Mobile App Reverse Engineering

By : Abhinav Mishra
5 (1)
Book Image

Mobile App Reverse Engineering

5 (1)
By: Abhinav Mishra

Overview of this book

Mobile App Reverse Engineering is a practical guide focused on helping cybersecurity professionals scale up their mobile security skills. With the IT world’s evolution in mobile operating systems, cybercriminals are increasingly focusing their efforts on mobile devices. This book enables you to keep up by discovering security issues through reverse engineering of mobile apps. This book starts with the basics of reverse engineering and teaches you how to set up an isolated virtual machine environment to perform reverse engineering. You’ll then learn about modern tools such as Ghidra and Radare2 to perform reverse engineering on mobile apps as well as understand how Android and iOS apps are developed. Next, you’ll explore different ways to reverse engineer some sample mobile apps developed for this book. As you advance, you’ll learn how reverse engineering can help in penetration testing of Android and iOS apps with the help of case studies. The concluding chapters will show you how to automate the process of reverse engineering and analyzing binaries to find low-hanging security issues. By the end of this reverse engineering book, you’ll have developed the skills you need to be able to reverse engineer Android and iOS apps and streamline the reverse engineering process with confidence.
Table of Contents (13 chapters)
1
Section 1: Basics of Mobile App Reverse Engineering, Common Tools and Techniques, and Setting up the Environment
4
Section 2: Mobile Application Reverse Engineering Methodology and Approach
8
Section 3: Automating Some Parts of the Reverse Engineering Process

Modifying and recompiling the application

Often, it is necessary to not just reverse engineer the application, but also change something, and then repack it. To create a modified APK, you will need to recompile the modified code and then sign the APK again.

Let's say we want to modify the encryption key in the application and then recompile it. To do so, you will need to perform the following steps:

  1. Decompile the APK. We have already decompiled the SecureStorage application using apktool, with the #apktool d app-debug.apk command.
  2. The decompilation process will provide us with the required smali files. So, let's open the EncryptionUtils.smali file.
  3. In this smali file, we can change the value of the encryption key to something else, such as abcdef12345.
  4. To recompile the application, we can again use apktool. Run the #apktool b command. Ensure that this command runs in the same directory where the application was extracted. It will compile the new...