Black box testing is an approach to penetration testing where the pentest team has no prior knowledge of the target system’s internal workings, infrastructure, or source code. This methodology simulates the perspective of an external attacker who has discovered your organisation online but has no insider information.
Testers must rely entirely on publicly available information and their own reconnaissance efforts to map the attack surface, identify potential entry points, and attempt to breach defences. This approach provides the most realistic simulation of how an actual attacker would approach your systems.
Whilst black box testing offers valuable insights into how your organisation appears to external threats, it does have some limitations. The lack of internal knowledge means testing can be time-consuming as testers spend significant effort on reconnaissance and discovery phases. Additionally, testers may miss vulnerabilities in areas they never discover or focus heavily on obvious entry points whilst overlooking subtle weaknesses.
Despite these constraints, black box testing remains highly valuable for organisations wanting to understand their external attack surface and validate that their perimeter defences can withstand determined attackers. It’s particularly relevant for internet-facing applications, external network infrastructure, and any systems accessible to the public.