Penetration testing—commonly called pen testing or ethical hacking—is an authorised simulated cyberattack performed against your computer systems, networks, or applications. The purpose is straightforward: find security weaknesses before malicious actors do, allowing you to fix vulnerabilities proactively rather than dealing with the aftermath of a real breach.

For businesses preparing for compliance certifications like SOC 2, ISO 27001, or PCI DSS, understanding penetration testing is essential. It's not merely a checkbox exercise—it's a critical component of a mature security posture that can protect your organisation from financial loss, reputational damage, and regulatory penalties.

How Penetration Testing Works

Unlike automated vulnerability scans that simply identify known weaknesses, penetration testing goes further. Skilled testers actively attempt to exploit vulnerabilities, chain together multiple weaknesses, and demonstrate the real-world impact of security gaps. This provides a far more accurate picture of your actual risk exposure.

Penetration testers—often called ethical hackers—use the same techniques, tools, and methodologies that criminal hackers employ. The crucial difference is that they operate with explicit permission and within clearly defined boundaries, working to strengthen your defences rather than compromise them.

Types of Penetration Testing

Different types of pen tests address different aspects of your security infrastructure. Understanding these helps you determine which assessments your organisation needs:

• External network penetration testing simulates attacks from outside your organisation's perimeter, examining how an internet-based attacker might breach your defences
• Internal network penetration testing assesses what damage could occur if an attacker gains access to your internal network—whether through a compromised device, stolen credentials, or a malicious insider
• Web application penetration testing focuses on vulnerabilities in websites, web applications, and APIs, often using the OWASP Top 10 as a baseline for common security flaws
• Social engineering testing evaluates your organisation's human defences through simulated phishing campaigns, pretexting calls, or physical intrusion attempts
• Wireless penetration testing examines the security of your Wi-Fi networks and wireless infrastructure
• Physical penetration testing tests physical security controls such as locks, access badges, CCTV systems, and security personnel procedures

Black Box, White Box, and Grey Box Testing

Penetration tests are also categorised by how much information the tester receives beforehand:

Black box testing provides the tester with minimal information—typically just the organisation's name and perhaps target IP ranges. This most closely simulates an external attacker with no insider knowledge, though it can be more time-consuming as testers must discover information that would otherwise be provided.

White box testing gives testers full access to documentation, source code, network diagrams, and credentials. This allows for more thorough testing in less time, as testers can focus on exploitation rather than reconnaissance.

Grey box testing falls between these approaches, providing testers with some information while withholding other details. This often represents the most realistic scenario, simulating an attacker who has gained partial access or knowledge of your systems.

The Penetration Testing Process

Professional penetration testing follows a structured methodology, typically consisting of these phases:

Pre-engagement and scoping: Before testing begins, the penetration testing company works with you to define objectives, scope, rules of engagement, and timelines. This ensures everyone understands what will be tested, what's off-limits, and how the engagement will proceed.

Reconnaissance: Testers gather information about your organisation and target systems. This might include examining public records, analysing your website, identifying email addresses, and mapping your network infrastructure.

Scanning and enumeration: Using specialised tools, testers actively probe your systems to identify open ports, running services, software versions, and potential entry points.

Vulnerability assessment: The gathered information is analysed to identify potential security weaknesses that could be exploited.

Exploitation: Testers attempt to exploit identified vulnerabilities, demonstrating real-world attack scenarios. This might involve SQL injection, cross-site scripting, privilege escalation, or other techniques.

Post-exploitation: After gaining access, testers explore what an attacker could achieve—accessing sensitive data, moving laterally through the network, or maintaining persistent access.

Reporting: The engagement concludes with a comprehensive report detailing findings, evidence, risk ratings, and remediation recommendations. Quality reports include both executive summaries for leadership and technical details for your IT team.

Why Penetration Testing Matters for Your Business

Penetration testing delivers value beyond simply finding vulnerabilities:

• Compliance requirements: Standards like PCI DSS, ISO 27001, and SOC 2 either require or strongly recommend regular penetration testing. For many businesses, it's a prerequisite for operating in their industry or working with certain clients.
• Risk prioritisation: By demonstrating which vulnerabilities are actually exploitable and what damage they could cause, pen testing helps you allocate security resources effectively.
• Security validation: Testing confirms whether your security controls, policies, and procedures actually work as intended under realistic attack conditions.
• Due diligence: Regular penetration testing demonstrates to clients, partners, and stakeholders that you take security seriously and actively manage cyber risk.
• Breach prevention: Identifying and fixing vulnerabilities before attackers find them is far less costly than recovering from a successful breach.

How Often Should You Conduct Penetration Testing?

Most security frameworks recommend penetration testing at least annually, but more frequent testing may be appropriate after significant changes to your infrastructure, following a security incident, when deploying new applications, or when entering new markets or handling more sensitive data.

Many organisations now adopt a continuous testing approach, combining regular penetration tests with ongoing vulnerability management to maintain consistent security visibility.

Choosing a Penetration Testing Provider

The quality of a penetration test depends heavily on the expertise of those conducting it. When evaluating providers, consider their certifications (such as CREST, OSCP, or CHECK), their experience with your industry and technology stack, their methodology and reporting quality, and their ability to provide meaningful remediation guidance.

A skilled penetration testing company doesn't just find problems—they help you understand your security posture and provide practical recommendations for improvement. The goal isn't to produce the longest list of vulnerabilities, but to help you build genuinely stronger defences.

Taking the Next Step

If your organisation hasn't conducted a penetration test recently—or ever—now is the time to start. Whether you're preparing for compliance certification, responding to client requirements, or simply want to understand your security posture, a professional penetration test provides invaluable insight into your real-world risk exposure.

Begin by defining your objectives and scope, then engage with a reputable penetration testing company to discuss your needs. The investment in testing today could prevent far greater costs tomorrow.