Black Box vs. White Box Penetration Testing

In today’s blog, we are going to explore the concept of Black Box vs. White Box testing. There are a lot of terms thrown around when it comes to security, and it is easy to get confused, especially when different sources use different definitions for each term. Not to worry, we’ll explore black box, gray box, and white box testing specifically as it pertains to penetration testing to try and de-mystify these terms.

Black Box Testing

Black box testing assumes the adversary, a penetration tester in this case, has zero knowledge of anything about your environment. This could apply to an external penetration test, a web application penetration test, or a physical penetration test. The type of test doesn’t really matter, rather the level of knowledge the tester has about the target environment going into the test is what matters. As an example, let’s use an external penetration test.

A black box external penetration test would start with testing team not knowing anything about the testing scope besides the name of an organization. In order to find out what machines to test, they would start with open source reconnaissance to figure out what systems belong to the organization and then proceed to try and gain access to those specific hosts. The advantage of a black box test is pretty obvious, as this is the same process an actual attacker would follow in a real-world attack. But the potential to miss perimeter hosts that should be assessed is much higher, as there may be isolated systems not easily discovered.

White Box Testing

White box testing, by contrast, is where the tester knows everything about the environment before testing begins. Sticking with our example of an external penetration test, this means that the tester knows all IP addresses/URLs in scope and everything about those systems, including things like what OS they are using, what services are listening, software versions installed, how they are configured etc. For a web application penetration test, the tester would have access to the underlying source code and would perform static code analysis as part of testing to help in identifying and validating vulnerabilities.

With white box testing, we are really getting away from how an actual attacker would target your organization, as they likely wouldn’t have access to this sensitive information. But with that being said, white box testing does have a distinct advantage in that it is the most comprehensive form of testing and most likely to identify all vulnerabilities within a system or environment.

Gray Box Testing: Triaxiom’s Approach

As one can surmise, gray box testing falls somewhere between black box testing and white box testing. There are hundreds of “shades” of gray, depending on how much information the tester knows going into an assessment. At Triaxiom, we want to balance two primary things when making this decision. First, we want to make sure our tests emulate the real-world threats and attacks your organization is most likely to encounter, which leans us more towards black box testing. However, at the same time, we want to make sure our tests are as holistic as possible, not just finding one way in but identifying all vulnerabilities within the testing scope. Additionally, we want to make sure our testing is meeting your compliance requirements at the same time, since this is an important aspect of security for many businesses.

In a true black box test, it’s possible an IP address won’t be discovered and therefore not tested. So following a gray box testing model allows us to get as close to black box testing as possible, while still ensuring we provide a thorough test. For an external penetration test, this means our engineer will start with at least the IP addresses that are in scope to ensure we get full coverage. If a client wants to do traditional black box testing, we can definitely do that as part of the assessment, but we will still typically reach out after the initial discovery stage to ensure we have an accurate scope and we can validate that the client owns any systems we discovered.

Our goal with any test is to help advance your goals for security as a business, so we’re happy to work with you on different scenarios or different “levels” of gray box testing that may better meet your expectations. Additionally, we’re always happy to provide testing recommendations based on what you want to get out of an assessment. Reach out to schedule a conversation with us so we can figure out which approach is right for your organization.