What exactly is reverse engineering and how is it used? See everything about the topic!

Understanding how each of them works can be a challenge and it is in this context that reverse engineering emerges as an essential tool. It is she who will reveal the secrets of each object.

A fundamental tool in the search for knowledge of how something was designed and built, that is, how this object exists and functions.

Want to understand everything about it?

Read this article until the end, and we will practice Reverse Engineering in Reverse Engineering.

What is reverse engineering?

To begin with, it’s worth summarizing with an example: as a child, did you have the habit of taking your toys apart? If so, perhaps you did it out of pure instinct, but, deep down, you were practicing reverse engineering , as it is also popularly known.

Throughout the process, in a simple act of deconstructing an object, the child not only unveils the toy’s secrets, but also acquires basic notions about logic, problem solving and analytical thinking.

In one simple movement, the child exemplifies a deep concept from the tech universe and shows how to reverse engineer it.

Generally speaking, Reverse Engineering is the process of disassembling, analyzing and understanding an existing product, device, computer program or system to discover how it works internally and how it was designed. This involves examining the final product and trying to deduce its functioning , structure and original design, often in order to gain insights, create improved versions or make changes. In short, reverse engineering involves taking something apart to understand how it was made and how it operates.

How does it work?

Reverse engineering has practical applications in several areas, but in technology, for example, its general process consists of analyzing in detail to understand how software works.

For example, when you don’t have the original specifications or the source code of a system, replicating its functionalities is the way to go. And to be able to carry out a detailed analysis of the code or the executable, it will be necessary to have solid knowledge of software architecture .

The reason is simple: this will increase the ability to interpret and gain insights from the analyzed system.

Therefore, understanding about software architecture and solutions will be important for a more complete work with reverse engineering.

Below, we list some of its uses:

• Comprehension: Internal understanding of objects, systems, devices or software, allowing engineers and researchers to understand how they were designed and how they can replicate their functions.

• Innovation: by understanding new processes, professionals can be inspired to create new solutions, which generates support for the creation of new systems and products.

• Security : In ethical hacking and IT security practices, it is also applied. Experts analyze systems to identify vulnerabilities and in this way can improve security.

• Market analysis : when it is possible to analyze competitors’ products, consequently, their characteristics and technologies can be mapped.

• Recreation : recreate or replicate similar functionality, architecture, or designs. It is worth noting that reverse engineering can involve legal and ethical issues, especially in relation to intellectual property.

Is reverse engineering a crime?

This point is important to reinforce and understand that the legality of reverse engineering can vary depending on intellectual property laws and local legislation in different countries.

In other words: it depends!

There are legal and illegal cases, but illegality is mainly related to the violation of intellectual property rights and other legal protection laws. Therefore, it is necessary to analyze the circumstances to understand whether there is, for example, authorization from the rights holder.

Often in software reverse engineering, the purpose of your application may be malicious, such as replication for piracy. This obviously makes it illegal and is a crime.

In other cases, it may be permitted if it is done for legitimate purposes, such as interoperability, research, education, or security.

It is important to emphasize that reverse engineering must be carried out ethically and legally. Many countries have specific regulations on reverse engineering, so it’s critical to understand the legal implications before starting this process. Additionally, reverse engineering can be complex and time-consuming, requiring advanced technical skills in programming, operating systems, and computer architecture.

How to reverse engineer?

The application of reverse engineering can vary depending on the field and context in which you are working. In the software area , it is a practice widely used in different sectors and fields and its use can vary depending on the industry, needs and objectives

Here are some general guidelines on how you can apply:

Em software:

Reverse engineering used in software is a process that can be carried out for a variety of reasons, such as understanding legacy software, correcting defects, improving interoperability, creating documentation or even for malicious purposes, such as exploiting security vulnerabilities.

Here are some common steps involved in software reverse engineering:

1. Obtaining the code : First, you need to obtain access to the source code, if available, or the machine code of the application you want to analyze. This may involve decompiling an executable, disassembling a binary, or analyzing source code when available.
2. Static Analysis : In this step, you examine source code or machine code without running the program. This may involve reading and understanding the flow of control, identifying functions, analyzing data structures, and identifying code patterns.
3. Code Disassembly : the decompilation step to transform executable code into a format closer to source code. This process ends up making it possible to study and understand the logic of the software . If you are working with machine code, you can use decompilation tools to convert the machine code back to high-level source code such as C, C++ or other programming languages.
4. Dynamic analysis : In this step, you run the program in a controlled environment and monitor its behavior. This might involve debugging the software, watching function calls, tracking variable values, and analyzing outputs.
5. Code engineering : Based on static and dynamic analysis, you begin to rebuild the software structure, identify algorithms and understand the logic behind the program’s operation.
6. Vulnerability Analysis : this step identifies possible vulnerabilities and security flaws in programs and applications.
7. Compatibility and Interoperability: is the need for software compatible with other systems? This step of software reverse engineering can help you understand the protocols and data formats used.
8. Documentation and Re-creation : Once you have a solid understanding of the software, you can create detailed documentation, flow diagrams, class diagrams, or even try to recreate part or all of the software based on your understanding.

Em APK:

Reverse engineering APK files, which are Android application packages , is a practice that is also widely used to understand how an application works internally, find out how certain features are implemented, fix problems, develop modifications or even identify security vulnerabilities.

The system developed by the Open Handset Alliance consortium restricts user and even application access to the internal resources of its operating system, which includes installed applications.

To further strengthen security, Google Play prevents the download of applications for conventional computers, only allowing them for tablets and smartphones.

The general steps involved in reverse engineering an APK file are similar to those performed for software, they are:

1. Obtaining the APK : Firstly, you need to obtain the APK file of the app you want to analyze. This can be done by installing the app on an Android device and then copying the APK from the device or downloading the APK from a trusted source such as the official Google Play store.
2. Decompilation : The next step involves APK decompilation, which is the conversion of the application’s machine code back to a high-level source code format such as Java files. There are several tools available to accomplish this task, such as APKTool, which is a widely used open source tool for decompiling and recompiling APKs.
3. Code Analysis : After decompilation, you will have access to the application’s source code in Java format (or other languages, depending on the implementation). You can use code editing tools to examine and analyze the code, understand the structure of the application, identify relevant control flow, classes and methods, as well as identify resources such as UI layouts, images and strings.
4. Resource Analysis : In addition to source code, APKs contain resources such as XML layouts, images, configuration files, among others. Analyzing these features can help you understand how the user interface is constructed and how the features are used in the application.
5. Reverse Engineering Binary Resources : In some cases, you may find parts of code that have been optimized and compiled to native machine code. Tools like machine code decompilers (eg IDA Pro) can be used to understand and reverse these parts of code.
6. Testing and Debugging : Throughout the reverse engineering process, it is important to test the modified or recompiled application to verify that the changes made are working as expected. Debugging tools can be used to identify problems and fix errors.

It is worth highlighting again that reverse engineering must be carried out responsibly and within legal limits. It is essential to respect copyright, application terms of use and intellectual property legislation.