Reverse Engineering Techniques for Penetration Testers 

Penetration testing is a highly in-demand job skill in today’s cybersecurity market. Data breaches cost companies USD 4.2 million in 2021 (IBM, 2021), and penetration testers can help companies protect and secure some of their most valuable assets.

In a World Economic Forum (2022) survey, 50% of executives said it would be difficult to respond to security threats due to the talent shortage. This means there is tremendous opportunity in cybersecurity for anyone hoping to advance their career. In this guide, we’ll explain why reverse engineering methods and tools are an important part of a cybersecurity professional’s skill set.

Common Reverse Engineering Methods

Finding vulnerabilities in software is complex, and the difficulty escalates with the size of the code base. To locate issues, testers rarely rely on one method alone, instead using a variety of penetration testing techniques, including reverse engineering.

Reverse-engineering analysis typically falls into two categories: static and dynamic. Many cybersecurity professionals use a combination of the methods and tools described below to find vulnerabilities.

Static Analysis

Static analysis debugs compiled code without actually running the application. In this process, testers use static code analyzers: software that examines the code to look for weaknesses that may lead to security incidents. These tools can find issues such as SQL injection and cross-site scripting (XSS) vulnerabilities. Static analysis can be further subdivided into two categories: source code analysis and binary code analysis.

How Do Static Code Analysis Tools Work?

Static analysis tools can evaluate compiled code before it runs, including both source code and binary code.

• Source code analysis: This technique looks at the source code to identify areas where there are flaws that an attacker could exploit. Source code analyzers can find buffer overflows, vulnerabilities to format string attacks, invalid pointer dereferences, and so on. Static analyzers can be used to find vulnerabilities in both client-side and server-side applications.
• Binary code analysis: This method involves analyzing the binary code of a piece of software using a hex editor, which displays all characters as hexadecimal numbers. This is then converted into machine code that can be read and analyzed for patterns or keys that can help uncover weaknesses within an application’s programming logic.

Common reverse engineering tools for static analysis include:

• Static Analysis Tool for Java (SATJ): This tool can be used to find defects in Java source code.
• PVS-Studio: PVS-Studio integrates with several popular integrated development environments (IDEs), including Microsoft Visual Studio and Eclipse. The tool includes a C/C++ syntax checker, an IDA Pro plugin, and integration with the Viva64 decompiler.

Dynamic Analysis

Dynamic analysis is an automated approach that runs through a program’s entire set of execution paths to identify vulnerabilities. Dynamic analysis tests all the possible paths of an application, as well as the behavior of each path, and finds vulnerabilities using predefined rules.

• Automated fingerprinting: Automated fingerprinting is a technique for identifying malicious code using heuristics to find commonalities—for example, applying a pattern for finding exploits in C++ to Java or another programming language. The idea is to create a “fingerprint” for each language, which can be thought of as a template that can be used to apply the same pattern for identifying malicious code across multiple programming languages.
• Preprocessor injection: The idea behind preprocessor injection is to inject shellcode into a program before it is compiled and run. Then, when the program is run, it executes the shellcode instead of the real code. This technique exploits a flaw in how some programs handle their command-line arguments.
• Symbol resolution: Symbol resolution involves finding functions in binaries and linking them to their correct symbols. This is useful because it helps identify unused functions in the binary.

Common engineering tools for dynamic analysis include:

JavaBeacon (JBeacon): This Java-based dynamic analysis tool can be used for static and dynamic analysis of Java applications.

Kali Linux: Kali is an open-source Linux distribution designed for penetration testing that includes multiple tools for static and dynamic application security testing, including:

• Nikto
• Maltego
• sqlmap
• WhatWeb
• WHOIS lookup

Why Should You Get Certified in Penetration Testing?

Penetration testing is a lucrative career. According to ZipRecruiter (2022), the average yearly salary for a penetration tester in the United States is USD 116,323. In addition to a solid understanding of information technology fundamentals and testing strategies, like reverse engineering, penetration testers also typically need knowledge and skills in the following areas:

• Network and application security
• Programming, especially scripting languages (e.g., Python, Bash, Java, Ruby, Perl)
• Threat modeling
• Comfort working in Linux, Windows, and macOS environments
• Familiarity with security assessment tools

The best way to start or advance your career in penetration testing is to complete training and obtain a certification. EC-Council’s Certified Penetration Testing Professional (C|PENT) certification is designed to equip you with expertise in the tools and techniques used in this rewarding field. Sign up today to start your path to a career in cybersecurity.