Pentest can be carried out in different modes: Black Box, White Box or Grey Box. Each of these scenarios has very distinct characteristics, which influence the analysis method, the scope of the assessment, the accuracy of the results obtained and the strategic purpose of the test.
Pentest Black Box
Black-box intrusion testing represents the most realistic form of external attack. In this scenario, the pentester has no prior knowledge of the target environment. He or she is placed in the same situation as a cybercriminal attempting to compromise a system from a totally external position, with no credentials, technical documentation or architecture diagram.
The test therefore begins with a long and meticulous reconnaissance phase, during which the auditor collects all publicly accessible information via passive and active reconnaissance techniques, also known as OSINT, such as enumerating domain names, scanning ports, or searching for data leaks exposed on the Internet. The aim of this mode is to assess the external attack surface, i.e. all vectors that can be exploited from the outside, often accessible via open services on the Internet. It applies particularly to public websites, exposed APIs, messaging services or remote maintenance systems.
Black Box testing measures the effectiveness of perimeter protections, such as firewalls, authentication mechanisms, detection of abnormal behavior or the robustness of interfaces in the face of SQL injections, XSS or other known vulnerabilities. However, the limitation of this approach is that it does not allow exploration of the system’s internal layers, nor identification of complex structural flaws, which require in-depth understanding of the architecture. Nevertheless, it remains a valuable tool for estimating the level of security perceived from the outside.
Pentest White Box
Unlike black-box testing, Pentest White Box is based on total transparency between the client organization and the auditor. The latter receives detailed information on the system to be audited: source codes, network diagrams, technical identifiers, server configurations, security policies, event logs and even access to pre-production environments.
The White Box approach enables in-depth analysis of the structure of the target application or infrastructure, with a view to a complete audit of compliance and resilience. The tester can examine code quality, look for business logic flaws, check the implementation of access controls or identify inadequate configurations likely to create attack vectors.
This method is often used as part of a software security review, to ensure compliance with best practices in secure development, or to validate the security posture of a complex system before it goes into production. The main advantage of White Box Pentest is its ability to cover an extended perimeter and detect vulnerabilities that are difficult to access in a black box, such as internal privilege elevations or design errors.
On the other hand, this approach assumes a high degree of collaboration between the organization’s technical teams and the auditor, and does not necessarily reflect the conditions of a real attack carried out by an external actor without prior information.
Pentest Grey Box
Between the two extremes of the black box and the white box, Grey Box Pentest offers an intermediate solution, where the auditor receives a limited level of information about the targeted system. This can take the form of user access without administrator privileges, partial documentation, or even simulated customer accounts to access certain interfaces.
This configuration corresponds to the posture of an attacker who has already gained a foothold in the system, such as a malicious employee, an external partner with remote access or a hacker who has compromised a low-level account. The Grey Box approach simulates realisticinternal attack scenarios, while limiting the scope of investigation to what an authenticated attacker could exploit. It offers a good balance between the representativeness of a plausible threat and the possibility of exploring sensitive technical areas, such as flows between services, network segmentation faults or access validation mechanisms.
Grey Box testing is often preferred by organizations wishing to assess the resistance of their defense mechanisms in depth, without exposing their entire environment to an external auditor. It also enables the reactivity of detection systems to be tested in the face of actions initiated from a legitimate but misused access, while guaranteeing a certain saving in time and resources compared with a full White Box analysis.