The type and scope of testing

The type of testing can be black box, white box, or an intermediate gray box, depending on how the engagement is performed and the amount of information shared with the testing team.

There are things that can and cannot be done in each type of testing. With black box testing, the testing team works from the view of an attacker who is external to the organization, as the penetration tester starts from scratch and tries to identify the network map, the defense mechanisms implemented, the internet-facing websites and services, and so on. Even though this approach may be more realistic in simulating an external attacker, you need to consider that such information may be easily gathered from public sources or that the attacker may be a disgruntled employee or ex-employee who already possess it. Thus, it may be a waste of time and money to take a black box approach if, for example, the target is an internal application meant to be used by employees only.

White box testing is where the testing team is provided with all of the available information about the targets, sometimes even including the source code of the applications, so that little or no time is spent on reconnaissance and scanning. A gray box test then would be when partial information, such as URLs of applications, user-level documentation, and/or user accounts are provided to the testing team.

Gray box testing is especially useful when testing web applications, as the main objective is to find vulnerabilities within the application itself, not in the hosting server or network. Penetration testers can work with user accounts to adopt the point of view of a malicious user or an attacker that gained access through social engineering.