Have you ever wondered how attackers and security researchers can figure out how a malicious program or a complex system works? In terms of malwares for example, how do they discover its secrets, weaknesses, or possibly hidden features? The answer to this question is reverse engineering. As it is one of the valuable skills especially for security professionals, let’s get deeper into this.

What is reverse engineering?

Reverse engineering is the process of analyzing a piece of software or hardware to understand its design and inner workings. In the field of cyber security, reverse engineering is essential for analyzing malicious programs and complex systems that pose a threat to the safety and privacy of users.

Why reverse engineering?

In the context of cyber security, reverse engineering can be used for various purposes, such as:

• Vulnerability discovery : This is one of the main goals of reverse engineering. By analyzing how a software works, reverse engineers can find flaws or weaknesses that can be exploited by attackers or fixed by developers.
• Malware analysis : This is another common use of reverse engineering. By examining how a malicious program works, reverse engineers can understand its functionality and purpose, determine how to remove it from a system or create defenses against it.
• Feature development : This is a less common but still valuable use of reverse engineering. By studying how a software works, reverse engineers can learn from its design or functionality, or develop new features or enhancements for it.

Reverse Engineering Techniques

There are two main techniques for reverse engineering software: static analysis and dynamic analysis.

Static Analysis

Static analysis involves examining the code itself or looking at its metadata, such as timestamps or file hashes. The key point of static analysis is that the analysis is done without having to run the decompiled code in Assembly. Because of this, static analysis can be used to understand what a piece of software does without worrying about it causing any damage.

Dynamic Analysis

Dynamic analysis involves executing the software to observe its behavior. As opposed to static analysis, it is done by running the code. Thus, dynamic analysis can be used to identify how the software behaves when it is running. Disassemblers and debuggers are two types of tools that can help with dynamic analysis of binary code.

Both static and dynamic analysis have their strengths and weaknesses. Static analysis would be less likely to cause damage to a system, for the reason we mentioned earlier. However it can be challenging to understand what a piece of software does without actually executing it. Dynamic analysis can provide more insight into the software’s functionality, but it can also trigger unwanted actions or alerts.

Reverse Engineering Tools

Dynamic analysis requires both disassemblers and debuggers. In fact, It is also possible to use many tools available for reverse engineering software, depending on the type and complexity of the software. Some of the most popular and useful tools are:

Disassemblers

These tools convert binary code into assembly language, which is easier to read and understand. It can help you understand the structure and logic of the program. Examples of disassemblers are IDA, Ghidra, and Radare2.

Debuggers

These tools allow the user to run the software step by step, pause it, modify it, or inspect its memory and registers. Examples of debuggers are OllyDbg, x64dbg, and WinDbg.

Decompilers

These tools attempt to reconstruct the original source code from the binary code. It converts an executable program to its original high-level source code. Examples of decompilers are Hex-Rays, JEB, and Snowman.

Hex editors

These tools allow the user to view and edit the raw bytes of the software. Examples of hex editors are HxD, HexEdit, and 010 Editor. Alternatively, xxd can be used for hex dump. .

Network analyzers

These tools capture and analyze the network traffic generated by the software. Examples of network analyzers are Wireshark, tcpdump, and Fiddler.

Reverse Engineering Process

In general reverse engineering will follow these three steps.

Information extraction

This step involves collecting all the relevant data about the product, such as its structure, functionality, behavior, and performance. Depending on the type of product, this may involve using tools such as disassemblers, debuggers, or decompilers to examine its physical or digital components.

Modeling

This step involves creating an abstract representation of the product based on the extracted information. This may involve using diagrams, graphs, equations, or pseudocode to describe the product’s logic, architecture, or algorithm.

Review

This step involves testing and validating the model to ensure that it accurately reflects the product’s behavior and functionality. This may involve comparing the model’s output with the product’s output, checking for errors or inconsistencies, or performing simulations or experiments.

Reverse engineering often requires analyzing and manipulating Assembly language, which can be unfamiliar and challenging for beginners or non-IT professionals. To master this skill, you need to have a solid grasp of hardware concepts (especially CPU architecture) and low-level programming principles.

Reverse Engineering Challenges

Reverse engineering is not an easy task. It requires a lot of skill, patience, and creativity. It becomes more challenging to reverse engineer code when software developers implement anti tamper technology as a way of deterring such analysis.

Obfuscation

This is a technique used by software developers to make their code harder to read and understand. Obfuscation can involve renaming variables and functions, removing comments and whitespace, encrypting strings and data, or adding junk code.

Encryption

This is a technique used by software developers to protect their code from unauthorized access or modification. Encryption can involve using cryptographic algorithms or keys to scramble the code or data.

Legal issues

Despite not directly related to tampering, this is a challenge that is commonly faced by reverse engineers who want to analyze proprietary or copyrighted software. Depending on the jurisdiction and the license agreement, reverse engineering may be illegal or unethical.

Conclusion

Reverse engineering is a valuable skill for cyber security professionals, as it allows them to analyze and understand complex systems and malicious programs. Reverse engineering involves extracting information, modeling the product, and reviewing the model. It can be done using various techniques and tools, such as static analysis, dynamic analysis, disassemblers, debuggers, decompilers, hex editors, and network analyzers. However, reverse engineering also faces some challenges, such as obfuscation, encryption, and legal issues. Therefore, reverse engineers need to be skilled, patient, and creative to overcome these obstacles and achieve their goals.