How to reverse engineer an iOS App?

06 Dec 2022

Reverse engineer an iOS app is a big challenge. It requires time and expertise and most of the time you need to own the code and be able to share it. AppScan has developped a methodology to analyze automaticly any app.

Why do we Reverse Engineer an App?

It is very interesting to understand who you are dealing with. What is its development strategy, what functionality does it prioritize? What technology has he chosen? How does it integrate with the system?

  • Understanding how the app works and its underlying architecture
  • Identifying potential security vulnerabilities and fixing them
  • Modifying the app to add new features or customize it for specific needs
  • Learning from the app’s code and design to improve one’s own app development skills
  • Competing with the app by creating a similar or improved version
  • Investigating potential copyright or patent infringement by the app developer.

Methodoloy

Reverse engineering an iOS app can be quite complex, and it’s not something that I would recommend unless you have a lot of experience with iOS app development and a good understanding of the underlying technologies. Here are the general steps that you would need to follow to reverse engineer an iOS app:

  • Jailbreak the iOS device that the app is installed on. This will give you access to the device’s file system and allow you to modify the app’s files and data.
  • Use a tool like iFunBox or iExplorer to access the app’s files on the device. These tools allow you to view and extract the app’s files, including its compiled code and resources.
  • Use a tool like Hopper Disassembler to disassemble the app’s compiled code into assembly language. This will give you a low-level view of the app’s inner workings, but the code will still be difficult to understand without a deep understanding of iOS app development.
  • Use a tool like IDA Pro to analyze the app’s assembly code and create a map of its functions and data structures. This will help you understand how the app works and how its different components are connected.
  • Use a tool like Cycript to attach to the app’s running process and explore its internal state. This will allow you to see how the app behaves at runtime and how it uses its resources and data.

As you can see, reversing an iOS app is a complex process that requires a lot of specialized knowledge and tools. It’s not something that most people would be able to do without a lot of experience and expertise.

List of tools to reverse engineer an iOS App

To reverse engineer an iOS application, one can use a tool such as Hopper Disassembler to decompile the application’s binary code and view the source code. Another option is to use a tool such as Frida to dynamically analyze the app’s behavior and inject code to modify its behavior. This can be useful for testing and understanding the app’s functionality and potential vulnerabilities.

  • Hopper Disassembler - used for disassembling and decompiling the binary code of an iOS app.
  • IDA Pro - a powerful disassembler and debugger for iOS applications.
  • Cycript - allows for dynamic analysis and manipulation of iOS apps.
  • Charles Proxy - used for intercepting and modifying network traffic in an iOS app.
  • Frida - a dynamic instrumentation framework that allows for the injection of code into running iOS apps.
  • otool - a command line tool for viewing the Mach-O header files and symbol table of an iOS app.
  • objdump - a command line tool for disassembling the binary code of an iOS app.
  • class-dump - a command line tool for generating header files from an iOS app’s binary code.
  • ReProvision - a tool for signing and installing modified iOS apps.
  • apktool - apktool is a tool for reverse engineering Android app packages.

AppScan in that ecosystem?

AppScan has developped a methodology to analyze any App and get some insights without source code. Discover AppScan offers