What Is Gray Box Penetration Testing and Why Should You Use It?

1. All You Need to Know About Gray Box Penetration Testing

2. What Is Gray Box Penetration Testing and Why Should You Use It?

3. Gray Box Penetration Testing as a Means to Plug In Security Loopholes

Given the massive increase in cyberattacks, organizations are gearing up to prevent ransom attacks on their systems. From conducting massive simulated hacking tests, to limiting access to outsiders using evaluation models, a lot is going on within this domain.

Penetration testing, also known as pen testing or ethical hacking, is a security assessment that uses network security tools to simulate an attack on a computer system or network.

Some standard pen testing techniques include black, white, and gray box testing. Never heard of gray box testing? Let’s dive in.

What Is Gray Box Testing?

Gray box testing is a testing type that looks at a system’s internal structure to identify potential errors or vulnerabilities.

As a penetration testing technique, it acts as an intermediary between black box testing, which looks at a system’s external inputs/outputs, and white box testing, which looks at the system’s internal code.

Security analysts and ethical hackers use gray box testing to find errors in a system’s functional and non-functional aspects.

In functional testing, the focus is on ensuring the system performs the required tasks correctly. In non-functional testing, the focus is on ensuring the system design meets performance, security, and scalability standards.

Gray box testing is essential to any quality assurance process, as it can help identify potential problems before they cause significant issues. It is crucial for complex systems, where a small error can have a ripple effect.

Gray Box Testing Techniques

Businesses use several types of gray box penetration tests. To outline a few:


Regression testing is a type of gray box penetration testing that tests for identified and fixed software flaws. This testing type ensures a software has not regressed to a less secure state.

Testers use the most commonly available pen testing tools and techniques to conduct regression testing. It can be done by re-running and verifying the outputs from previous runs with the new results derived from recent code changes.

Regression testing is essential because it ensures that the inherent code changes have not introduced new vulnerabilities.


The Matrix technique involves breaking down the target system into different areas, or variables, and testing for each variable’s vulnerabilities.

For example, the first variable might be the network infrastructure, followed by the operating system, applications, and data.

Each variable is tested for weaknesses that a hacker can exploit to access the subsequent variable. This is proven to be a very effective way to find vulnerabilities because it allows you to focus on specific variables at a time and understand how it works.

Additionally, the Matrix technique can help you identify potential attack paths that you may not have considered otherwise. It provides a clear picture of the system’s security posture.

Orthogonal Array Testing

Orthogonal array testing is a powerful gray box testing technique that has the potential to uncover a wide range of software defects.

This technique covers arrays, which ensures that all pairs of input values ​​are exercised at least once. Orthogonal array testing helps test all possible combinations of input values, making it a potent tool for uncovering defects.

Orthogonal array testing is a gray pentest technique that reduces test cases without coverage. In theory, you could reduce the number of test cases you need to run while still testing the complete functionality of your software.

Pattern Technique

A pattern technique is a powerful tool for ethical hackers, who wish to detect system vulnerabilities. Using this technique in conjunction with other gray box testing techniques, gives you a comprehensive view of the system’s security.

While it can be challenging to test a system for all potential vulnerabilities, the pattern technique is invaluable for testing common and uncommon vulnerabilities.

Downsides of Gray Box Penetration Testing

Like the two sides of a coin, there are a few limitations to gray box penetration testing that you should consider when conducting this type of assessment. Some limitations are outlined below:

  1. Since gray box testing involves having prior knowledge of the system in question, it may not be possible to simulate the actions of an actual attack from end to end.
  2. Gray box testing may not be able to identify all potential security vulnerabilities since the tester may not have complete visibility of the system.
  3. Given the application mapping and analysis process and the limited access to the source code, the testing speed is significantly slower than white box testing.

Should You Opt for Gray Box Testing?

You need to consider several factors before deciding whether to opt for gray box testing or not. Some of these factors include, but are not limited to, the following:

  1. The first factor is the level of access to your testing team’s code base. If the team has limited access, they may not be able to understand the code fully and end up missing critical bugs.
  2. The second factor is the size and complexity of the code base. A large, complex code base is more likely to have hidden bugs than a small and simple code base.
  3. Last but not least, you should pay attention to the time and budget constraints of the project. If you’re working in a constrained deadline and budget, it may not be feasible to undertake a comprehensive white box testing approach.

In general, gray box testing is a good compromise between white and black box testing. It can prove more efficient and effective than black box testing while providing some coverage.

Gray Box Testing as a Means of Pen Testing

Penetration testing is one of the leading ways to validate a system’s security. It is an integral part of an organization’s software development lifecycle.

As a penetration testing methodology, gray box pen testing combines the benefits of white box and black box testing. However, in simple terms, even penetration testing programs follow a hierarchy, with black box testing occupying the top position.

Before indulging in any testing methodology, you should carefully weigh the security resources and choose a suitable plan. So ensure you cover the basics of each testing type, to make a prudent decision.

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