§1
Black box, grey box and white box testing
Security testing approaches differ in how much information testers receive. In black box testing, testers start with only a URL or app, like an external attacker. This shows what an outsider can discover, but limited time may be spent on reconnaissance rather than finding deeper issues in the application itself.
Grey box testing provides user accounts with different roles and some documentation. It is the most common approach for web and mobile applications, because it efficiently tests what matters most: whether users can access data or functions they should not, such as another customer's records or admin features.
White box testing gives testers access to source code, architecture diagrams and configuration. Combining code review with live testing finds issues that are hard to detect from outside, such as weak cryptography, hidden endpoints or insecure handling of secrets, and provides the deepest coverage for the time invested. The right choice depends on goals and budget. Many organizations use grey box testing for regular assessments and add white box reviews for high-risk components, such as payment processing or authentication services.


