Penetration Testing

In penetration testing, a company hires experts to break into its own systems. That sounds paradoxical, but it follows a simple logic: whoever knows their weaknesses can close them before someone else exploits them. The hired experts act with explicit permission — that distinguishes them legally and morally from real attackers. In the end, there is no damage, but a detailed report on the security gaps found. Companies conduct such tests regularly, often because laws or contractual partners require it.

Penetration Testing as a Safety Net

Software developers build systems as securely as they can assess at the time of development. But no team thinks of every possible attack method. Real attackers think differently than developers — they don’t look for what works, but for what fails unexpectedly.

A penetration test brings exactly this different way of thinking into the house. Studies regularly show that even well-maintained systems have, on average, several exploitable vulnerabilities. Without targeted tests, these often remain undiscovered for years. The financial and reputational damage of a real breach far exceeds the cost of a test.

For certain industries, penetration testing is not a voluntary measure. Banks, hospitals, and operators of critical infrastructure are legally required in many countries to have their systems regularly tested. Anyone processing credit card data must also demonstrate regular tests under the international standard PCI DSS — a set of rules for payment security.

The Process of a Pentest

A pentest begins with a clear agreement: what may be tested, and what may not? This so-called scope defines whether only a single web application is examined or an entire company’s network. This is followed by the reconnaissance phase, in which the testers gather information about the target — often using the same tools that real attackers also use.

In the next step, the experts actively attempt to penetrate the system. They test known vulnerabilities in software, check whether passwords are too weak, and see whether various security gaps can be combined to penetrate further into the system. Importantly, they document every step precisely so that the final report is traceable.

Three variants are distinguished according to the testers' level of knowledge. In a black-box test, the experts know nothing about the system — just like an external attacker. In a white-box test, they receive full access to source code and documentation. The grey-box test lies in between: the testers know rough structures, but no details. Each variant finds different types of vulnerabilities.

Pentests in Products and Headlines

Many well-known tech companies regularly publish so-called security reports, in which they summarize the results of external pentests. Apple, Google, and Microsoft hire external security firms to test their products — and also pay bounties when external researchers report vulnerabilities on their own initiative. Such programs are called bug bounties.

In connection with AI systems, penetration testing is currently gaining significant importance. Language models — that is, AI systems that understand and generate text — can be induced by cleverly formulated inputs to deliver unwanted responses or bypass security mechanisms. This attack method is called prompt injection. Companies developing AI products are increasingly hiring specialized teams to systematically test exactly such vulnerabilities.

The term frequently appears in public discourse when well-known data breaches are analyzed. It often turns out that a simple vulnerability remained undiscovered for years — one that a pentest would likely have found. This makes penetration testing one of the few security concepts that, even after spectacular hacking attacks, is not criticized but discussed as a solution.