Cyber Security Testing

Know your risks and find your weak spots with our cyber security testing services.

Understanding how to strengthen your digital defences demands a practical assessment. Worryingly, in the last year, 43% of UK businesses experienced cyber security breaches, a figure that climbs even higher for larger organisations. These attacks can be costly, with the average cost of the most disruptive breach for medium-sized businesses reaching around £10,830. Despite this clear and present danger, a 2025 report indicates that only 22% of businesses have a formal cyber security incident management plan, and in 2024, just 31% undertook a cyber security risk assessment or health check, although this figure has seen a positive increase among small businesses in 2025.

Cyber security testing, commonly known as penetration testing, is that crucial hands-on process, simulating real-world attacks to identify vulnerabilities within your systems before malicious actors can exploit them. By proactively identifying these weak spots, you can significantly reduce your risk exposure, and the potential financial and reputational damage associated with cyber incidents.

The approach to this testing, however, can vary significantly, each offering unique insights into your business resilience and security posture. The following sections explore the different methodologies we use, from understanding the level of prior knowledge our testers have to the specific environments being assessed, ultimately providing a comprehensive view of how we can help you fortify your assets in an ever-changing digital landscape.

Types of penetration testing

Cyber security testing isn’t one-size-fits-all. The level of information provided to our testers beforehand dictates the approach. The types of penetration testing are often categorised as closed box, glass box and translucent box testing.

Closed box testing

Closed box testing simulates a real-world, external attacker scenario. Our testers have no prior knowledge of your systems or infrastructure. They start from scratch, performing reconnaissance and attempting to find vulnerabilities based purely on publicly available information and their own techniques.

Glass box testing

With glass box testing, we are provided with full knowledge of your systems, including network diagrams, source code and credentials. This allows for a highly focused and efficient assessment, enabling us to identify deeply rooted vulnerabilities that might be missed in a closed box approach.

Translucent box testing

In this approach, our testers are given partial knowledge of your systems, such as network maps or high-level architectural diagrams. This allows us to conduct more targeted cyber security testing than a closed box approach, while still maintaining a degree of realism.

The box we operate within will be determined by your specific needs and the goals of the test. Each approach offers unique benefits in uncovering different types of vulnerabilities and simulating various threat scenarios. Our team will work with you to determine the most appropriate methodology for your organisation.

Internal penetration testing

Humans are your weakest link within your organisation, and it’s important to conduct internal penetration testing to simulate attacks from the perspective of an insider. This could be a malicious employee, a compromised user account, or a threat actor who has already bypassed your external defences.

This type of cyber security testing is vital for understanding your true business resilience and identifying vulnerabilities that might not be apparent from an external assessment alone. It helps you evaluate:

• The level of access a disgruntled employee could gain
• How easily a compromised workstation could be used to pivot to other sensitive systems
• Whether internal security controls are effective in limiting the impact of a breach

What does internal penetration testing cover?

This service meticulously examines your internal network, systems, and applications, typically including:

• Network segmentation controls
• Internal authentication mechanisms and access controls
• Identifying unpatched software and misconfigurations
• Attempting to gain higher levels of access than a standard user should possess
• Lateral movement testing to simulate an attacker moving from one compromised system to other systems
• Assessing the security of internally developed/hosted web apps
• Evaluating internal Wi-Fi networks
• Examining the configurations/controls on workstations and servers

External penetration testing

Your external-facing infrastructure is the gateway to your organisation. It’s the primary target for cyber criminals seeking to gain unauthorised access to your systems and data. External penetration testing simulates real-world attacks originating from outside your network to identify vulnerabilities in these publicly accessible assets.

This proactive approach allows you to understand your exposure to external threats and make the necessary changes to safeguard your system from a real attack.

What does external penetration testing cover?

This service is focused on analysing all your internet-facing assets, including:

• Firewalls and Intrusion Prevention Systems (IPS)
• Web servers and applications
• Email servers (SMTP)
• Domain Name System (DNS) servers
• Virtual Private Networks (VPNs) and remote access points
• Publicly exposed APIs
• Cloud infrastructure (if publicly accessible)

This service is often referred to as perimeter penetration testing and is an ‘ethical hacking’ exercise designed to uncover security flaws before they can be exploited. These exercises involve gathering information about your external infrastructure, identifying open ports and services, conducting a vulnerability assessment, and finally providing a detailed report outlining the findings.

Your cyber perimeter is the first line of defence against external threats, so it is worth making sure they are as robust as can be to protect sensitive data and maintain business continuity.

Web application penetration testing

Your web applications are critical gateways for customer interaction, business processes and often, sensitive data. Ensuring their security is paramount to protect your organisation from a wide range of cyber threats. Web application penetration testing is a specialised security assessment focused on identifying vulnerabilities within these applications.

Our web application penetration testing goes beyond surface-level checks, simulating real-world attacks to uncover security flaws stemming from insecure development practices in the design, coding and deployment of your software and websites.

What does web application penetration testing cover?

Our comprehensive testing methodology delves deep into the functionality and underlying code of your web applications, typically involving examining login mechanisms, session management and password recovery processes, as well as actively searching for web app flaws.

Testers will be looking for the following:

• Vulnerabilities in Cross-Site Scripting (XSS) that could allow attackers to inject malicious scripts into your website and target users
• Testing for weaknesses that could allow unauthorised access to or manipulation of your database
• Assessing if attackers can bypass authorisation and access resources they shouldn’t
• Improperly configured servers, applications, and security headers
• Insecure deserialization that could allow attackers to execute arbitrary code
• Weaknesses in third-party libraries and frameworks
• How your web app interacts with user browsers

Automated penetration testing

The sheer volume and complexity of some IT environments can make manual penetration testing resource-intensive and time-consuming for certain businesses. Automated penetration testing leverages specialised software tools to efficiently scan and identify potential vulnerabilities across your infrastructure and applications.

Automated penetration testing is a powerful initial sweep, providing broad coverage and quickly highlighting common security weaknesses. These tools can systematically probe systems, identify open ports, enumerate services, and detect known vulnerabilities based on extensive databases and predefined rules.

What does automated penetration testing cover?

While the scope can vary depending on the tools and configuration, automated testing typically includes:

• Identifying known software vulnerabilities, missing patches and misconfigurations across your network, servers, and applications
• Discovering open ports and the services running on them, which can be potential entry points for attackers
• Identifying common web vulnerabilities like some types of SQL injection and cross-site scripting (XSS)
• Assessing systems against certain security benchmarks and compliance requirements
• Identifying insecure configurations in operating systems, applications, and network devices.

Automated penetration testing can automate repetitive tasks which allows for faster and more frequent testing. It can also rapidly scan large and complex environments, providing a valuable initial security overview at a potentially lower cost than other penetration testing methods. Automation also provides ongoing visibility and can be scheduled regularly for continuous monitoring.

However, it’s crucial to understand that automated penetration testing is not a replacement for manual penetration testing. While automation provides speed and broad coverage, it often lacks the in-depth analysis, contextual understanding, and ability to identify complex, logic-based vulnerabilities that skilled human testers possess.

Ready to test your business resilience?

Ultimately, the right type of cyber security testing for your organisation depends on your specific security objectives, the nature of your infrastructure and your risk appetite. Whether it’s simulating an external attacker with a closed box approach, leveraging full system knowledge in a glass box test, focusing on internal threats, or rigorously examining your web applications, our expert team at Net-Defence offer penetration testing as a service and are equipped to deliver actionable insights.

We can help protect your organisation with cyber security testing designed to detect issues within systems and infrastructures. Our services encompass perimeter penetration testing and web application penetration testing to pinpoint vulnerabilities and poor security controls. Furthermore, our automated security testing offers a regular program to find potential weaknesses and provides insights into the degree of risk.

Following our testing, you can expect a summary of your organisational security health, a risk-based report for each identified vulnerability, evidence of findings and their real-world impact and included retesting. Our skilled testing team uses a blend of experience and automated and manual techniques to assist you in building the most effective defence against emerging threats.

By understanding these different testing methodologies and leveraging our penetration testing as a service, you can make informed decisions about how best to protect your business against evolving cyber threats.