White-Box vs. Grey-Box vs. Black-Box Penetration Testing

Table of Contents

There are different types of penetration testing, and it can be confusing to figure out which is the best type to improve your overall cybersecurity. Using either white-box, black-box, or grey-box testing will help you define the hacker’s perspective that simulates the most insightful attack on your systems. In this blog post, we will explore the basics of white-box, black-box, and grey-box penetration testing, from what each testing approach is and what its main limitations and uses are to choosing the best approach for your organization.

What is white-box, grey-box, and black-box penetration testing?

White-box penetration testing

In a white-box pentesting project, the penetration tester is given full access and prior knowledge to find vulnerabilities in an organization’s applications and systems. This type of testing is also called clear-box testing, glass-box testing, transparent-box testing, and structural testing. White-box penetration testing is a simulated attack in which the tester, using a high-privileged account, aims to exploit both internal and external weaknesses. These weaknesses can be logical or structural vulnerabilities, security exposures or misconfigurations, insecure development code, and insufficient defensive measures.


  • Can find more vulnerabilities than black-box or grey-box testing.
  • Tester is less likely to miss a vulnerability.
  • Provides a wider perspective than a typical attacker’s.


  • Time-consuming.
  • Can be expensive.
  • Requires highly-skilled testers.


The main challenge for testers with white-box testing is having to sift through huge amounts of available data to identify potential areas of weaknesses, making it the most time-consuming and consequently the most costly type of testing for clients. However, white-box testing provides a comprehensive assessment of both internal and external vulnerabilities and should be used when thorough testing is required.

Typical uses

White-box penetration testing is usually used by organizations that have a lot of resources and want to find as many vulnerabilities as possible in their systems. It can also be used to assess the effectiveness of an organization’s security controls and to find hidden vulnerabilities that may have been missed in other types of testing.

Black-box penetration testing

In a black-box penetration testing project, the penetration tester is given no prior access or knowledge for the system under testing. This means that the tester must obtain sensitive knowledge and system access through patient reconnaissance. In this most realistic form of simulated attack, the tester aims to find the vulnerabilities in a system that are exploitable in an organization’s public-facing networks and applications.


  • Tester is more likely to think like an attacker.
  • Tester is less likely to have preconceived notions about the system.
  • Lower probabilities of false positives.


  • Takes longer to find vulnerabilities.
  • May miss some vulnerabilities.
  • Difficult to automate.


The main challenge for testers with black-box testing is that they must rely on their own skills and knowledge to find vulnerabilities, which can lead to overlooking some security issues. Also, if the tester cannot breach the perimeter, then no vulnerability in the internal network can be identified and remediated.

Typical uses

Black-box penetration testing can be used for functional or regression testing, meaning that it can be used to test new features or changes in an application before they are released.

Grey-box penetration testing

In a grey-box penetration testing project, the penetration tester is given some prior access and knowledge to the system under testing. This might include a low-privileged user access along with some application logic knowledge and network infrastructure mapping. In this more efficient, best-of-both worlds simulation, the tester starts from inside an organization’s perimeter to find more vulnerabilities in business-critical systems.


  • May help catch flaws that developers have missed.
  • Prioritization of testing may uncover more key vulnerabilities.


  • May not be as comprehensive as white-box testing.
  • Testers may miss critical source-code vulnerabilities.


The main limitations of grey-box testing include the potential for false negatives, because the tester does not have full access to all areas of the system. Also, because the grey-box tester has some level of access, they may not think to look for certain types of vulnerabilities that a white-box or black-box tester would.

Typical uses

Grey-box penetration testing is typically used for conducting first-time or most regular penetration tests for organizations of any sizes and industries. This approach also works well for testing cloud-based applications, which require special permissions to access.

What penetration testing approach is right for your organization?

Starting with your security concerns or objectives can help answer this question. Is it to find as many vulnerabilities as possible? Or, is it about testing the effectiveness of your organization’s existing security controls? Or, is it to find hidden vulnerabilities that have been missed in other types of testing? Also, defining the scope, efficiency, speed, and cost that is right for you will also help your decision-making process.

Scope or coverage

How much of your system do you want or need to be tested? Your testing scope will vary depending on the size and complexity of your system, as well as your organization’s security concerns and goals.


Are you looking for a comprehensive test that covers all aspects of your system? Or, are you more concerned with the effectiveness of specific controls? The expected effectiveness of your testing will help you understand what kind of test is right for your needs.


How fast do you need your testing results? Defining this aspect upfront can help you understand which type of test is best suited for your organization.


How much are you willing to spend on penetration testing? Also, how much time and resources do you have to dedicate to the project? Your organization’s budget and available resources are important factors when deciding on the right type of penetration test.

Small businesses with limited resources might want to start with a grey-box or black-box penetration test since it would be more efficient in terms of time and cost; On the other hand, large businesses with more resources might want to consider white-box penetration testing to generate a more comprehensive list of vulnerabilities; And finally, businesses in heavily regulated industries might be required to undergo regular white-box penetration testing, this to ensure their compliance with a strict regulation and avoid costly fines.

In any case, it all comes down to identifying your business-critical assets and the best approach or strategy to protect them. At the end of day, what matters is not the color of your testing approach, but simply how effectively any type of approach or any blend of approaches will help you do either of the following:

Final thoughts

Understanding what white-box, grey-box, and black-box penetration testing are will help you make an informed decision about which type is right for your organization. Each approach has its own set of pros and cons, so it’s important to understand the risks and benefits associated with each before making a decision. Also, keep in mind that no single type of test can offer a complete picture of your system’s security. A combination of penetration testing approaches might be necessary to get a more comprehensive view of your system’s vulnerabilities.

Contact us if you need help kicking off your penetration testing project.

Share this article on social media:

Subscribe to Our Newsletter!
Stay on top of cybersecurity risks, evolving threats and industry news.
MM slash DD slash YYYY

Recent Blog Posts


Featured Services

The Latest Blog Articles From Vumetric

From industry trends,  to recommended best practices, read it here first:

Tell us about your needs.
Get an answer the same business day.

Tell us about your needs.
Get an answer the same business day.

Fill out the form below and get an answer from our experts within 1 business day.

Got an urgent request? Call us at 1-877-805-7475 or Book a meeting.


What happens next:

  • We reach out to learn about your objectives
  • We work together to define your project's scope
  • You get an all-inclusive, no engagement proposal

MM slash DD slash YYYY
This field is for validation purposes and should be left unchanged.
Scroll to Top

Penetration Testing Buyer's Guide

Everything You Need to Know

Gain confidence in your future cybersecurity assessments by learning to effectively plan, scope and execute projects.
MM slash DD slash YYYY


Enter Your
Corporate Email

MM slash DD slash YYYY
This site is registered on wpml.org as a development site.