Penetration testing is an authorised, simulated cyber attack on your systems, carried out by security professionals to find and safely exploit weaknesses before real attackers do. Unlike an automated scan, it proves what an attacker could actually achieve. It is one of the most direct ways to understand and reduce your real security risk.
What penetration testing is
Penetration testing, often shortened to pen testing, is a controlled and authorised attempt to break into your own systems, carried out by security professionals on your behalf. The idea is simple and powerful: rather than waiting to find out how an attacker could compromise you, you have skilled testers try it first, safely, so you can fix the weaknesses before a real attacker finds them.
A penetration test answers a practical question that no checklist can: if someone genuinely tried to attack this, how would they do it, and how far would they get. It is the difference between assuming your defences work and proving whether they do.
How it differs from a vulnerability scan
People often confuse penetration testing with vulnerability scanning, but they are quite different. A vulnerability scan is automated. It checks your systems against a database of known issues and produces a list of potential weaknesses. It is fast, broad and useful for routine coverage, but it has limits: it produces false positives, misses anything not in its ruleset, and cannot tell you whether a given issue is actually exploitable.
A penetration test is driven by a human. A tester takes the potential weaknesses and tries to exploit them, proving which are real and what an attacker could actually do with them. Crucially, a tester also finds things a scanner never could, particularly business logic flaws that only make sense in the context of how your specific systems work. A scan gives you a list of maybes. A penetration test gives you facts.
The main types
Penetration testing covers different parts of your environment, and there are several common types:
- Web application testing, assessing your websites and web apps
- Network testing, external and internal, assessing your systems and infrastructure
- Cloud testing, assessing your cloud configuration and workloads
- Mobile application testing, assessing your iOS and Android apps
- Social engineering testing, assessing how your people respond to attacks like phishing
- Red teaming, a broader, goal-driven simulation of a real attacker
Which types you need depends on what you have and what you want assurance over. Many organisations combine several to get a complete picture of their risk.
What happens during a test
A well-run penetration test follows a clear process. It starts with scoping, agreeing what will be tested, how, and any boundaries, so everyone is clear and the test is safe. The testing itself is then carried out, with the tester probing and safely exploiting weaknesses. Throughout, testing is conducted carefully to avoid disrupting your live systems.
The engagement ends with a report and, ideally, retesting. The report documents what was found and what it means. Retesting, after you have fixed the issues, confirms that the fixes actually closed the gaps rather than trusting they did. That full cycle, scope, test, report, remediate, retest, is what delivers real value.
What a good report gives you
The report is where the value lands, and a good one speaks to two audiences. Engineers need the technical detail to understand, reproduce and fix each issue. Leadership needs a clear view of the business risk, prioritised by what an attacker could realistically exploit, without wading through technical detail. A quality report serves both, and it includes practical remediation guidance so you know not just what is wrong but how to fix it.
A report that is just a raw list of findings, with no prioritisation or guidance, is far less useful. The best reports turn testing into action.
Why and how often to test
Penetration testing matters because it gives you a genuine, evidence-based understanding of your security, rather than assumptions. It finds the weaknesses that matter before attackers do, supports compliance requirements, and gives you confidence that your defences hold. For many organisations it is also expected by customers, insurers and regulators.
Because systems change constantly, and every change can introduce a new weakness, testing should be regular rather than a one-time event, and it should follow significant changes such as major releases or infrastructure updates. A test reflects the state of your systems on the day it ran, so keeping testing current keeps your assurance current.
If you want to understand your real security risk through expert testing, our penetration testing services cover the full range, and our red teaming services provide a broader, goal-driven simulation for organisations wanting the deepest assurance.
For background on testing approaches, see recognised references such as OWASP or the ACSC.
Frequently asked questions
What is penetration testing?
Penetration testing is an authorised, simulated cyber attack on your systems, carried out by security professionals to find and safely exploit weaknesses before real attackers do. It proves what an attacker could actually achieve, so you can fix the gaps first.
How is it different from a vulnerability scan?
A vulnerability scan is automated and lists potential weaknesses, while a penetration test is human-driven and proves which weaknesses are genuinely exploitable and what an attacker could do. Testing also finds business logic flaws that scanners cannot understand.
What are the types of penetration testing?
Common types include web application, network, cloud, mobile application and social engineering testing, along with red teaming, a broader goal-driven simulation. Which you need depends on what you have and what assurance you want.
How often should you test?
Regularly, and after significant changes such as major releases or infrastructure updates. A test reflects your systems on the day it ran, so ongoing testing keeps your assurance current as your environment changes.
