Types of Penetration Testing Explained: A Guide for Businesses

Penetration testing is one of the best ways for any organisation to improve its overall cyber security posture. To put it simply, penetration testing is a simulated cyberattack on a company’s systems. When done correctly, usually by a specialist tester, penetration testing identifies any vulnerabilities within your system, allowing you to address them before they’re exploited by a real cyber attack.

As cyber security threats evolve in complexity and persistence, penetration testing (also known as pen testing) remains one of the most proactive steps you can take to uncover security vulnerabilities before attackers do.

Whether you’re an IT Director, CISO or compliance lead, understanding the different types of penetration testing can help you strengthen your cyber resilience, meet regulatory obligations, and stay ahead of threats.

In this article, we break down the different types of penetration testing and how to decide which ones are right for your business, industry and compliance requirements.

Key Takeaways

• Penetration testing is a simulated cyberattack used to identify and fix security vulnerabilities before they can be exploited by real attackers.
• Black box, white box, and grey box testing methods offer different levels of access and insight, helping simulate a variety of real-world scenarios.
• CREST certified penetration testing providers offer the assurance of quality and industry best practice, using frameworks such as the OWASP Top 10.
• Pen testing should be performed regularly across multiple layers of infrastructure, including web apps, mobile apps, cloud services and internal systems.
• Actionable post-test reporting is key; the real value lies in the remediation of findings and the long-term improvement of your cyber resilience.

What Is Penetration Testing and Why Does It Matter?

There’s no doubt that you will have heard of pen testing or be familiar with the concept, whether from your IT or developer teams, your cyber insurance provider, or your industry regulator. But what is its purpose, and when should it be utilised?

The Purpose of Penetration Testing

Penetration testing is one of the best possible ways to proactively measure and identify vulnerabilities in your cyber security. It simulates a real world cyberattack on your systems, applications or networks to identify weaknesses and provide remediation guidance.

Simulating the techniques used by an actual attacker gives you one of the most comprehensive views of how your business’s cyber defences work in real time. This allows you to take a proactive response to improve your cyber security posture and address issues before they have an opportunity to be exploited.

Done right, pen testing can help you to understand:

• Where a hacker might break in
• How would your current defences cope
• The real-world impact of a breach
• Where to prioritise improvements

When Should Pen Testing Be Used?

CREST and the UK’s National Cyber Security Centre (NCSC) recommend pen testing be conducted at least annually. But there are many business critical moments when it’s essential to conduct tests, such as:

• After any major system or infrastructure changes
• Before launching a new service or application
• Following a merger, acquisition or cloud migration
• In response to a breach or security incident
• To maintain compliance with standards like ISO 27001 or PCI DSS

Regulatory and Compliance Drivers in the UK

Pen testing isn’t just good security practice; it also supports a wide range of regulatory frameworks:

• ISO 27001: While not explicitly required, penetration testing supports Annex A.12 and A.18 by helping to identify and address system vulnerabilities.
• GDPR: Article 32 calls for ‘appropriate technical and organisational measures’ to protect data, which pen testing helps to execute and demonstrate.
• NIS2: For operators of essential services, regular testing is vital to safeguard critical national infrastructure.
• PCI DSS: Requires regular internal and external pen testing for cardholder data environments.
• DORA: In the financial sector, threat-led penetration testing is a core part of operational resilience strategy.

What Are The Main Types of Penetration Testing?

Your business, systems, applications, and what you use them for are unique to you, which means the types of penetration testing that will work best for you are, too. Here are some of the main types of penetration testing you’ll come across.

Network Penetration Testing

Network penetration testing focuses on your internal and external network infrastructure. It uncovers vulnerabilities in firewalls, routers, VPNs, servers, and cloud services, helping you understand if attackers can get in, and what they could access if they do.

• Internal penetration testing imitates an insider threat and is often carried out following or in conjunction with an external test.
• External penetration testing evaluates the vulnerabilities of external assets, including cloud infrastructure, email and file sharing facilities.

Web Application Penetration Testing

Web applications are among the most common attack vectors, and often the least protected.

Web app penetration testing simulates an attack on specific web apps to ensure that they’re secure against attacks.

This testing targets vulnerabilities such as:

• SQL injection
• Cross-site scripting (XSS)
• Authentication bypass
• Session hijacking

It’s vital to conduct regular web app testing for ecommerce platforms, portals, or any app handling sensitive data.

Wireless Penetration Testing

Unsecured Wi-Fi can be an open door for attackers, and as remote, hybrid, and work from abroad models become more popular, this is a very real risk for businesses.

Wireless pen testing looks for:

• Weak encryption protocols (like WEP)
• Rogue access points
• Misconfigured routers
• Insecure SSIDs or passwords

This type of penetration testing is ideal for offices with guest networks or shared workspace environments.

Cloud Infrastructure Penetration Testing

As cloud adoption grows, so do the risks. You should be conducting regular cloud penetration testing to ensure that no weaknesses have been created during implementation, interconnection, or subsequent upgrades of your cloud infrastructure.

Cloud pen testing checks for:

• Misconfigured S3 buckets or permissions
• Poor access control (IAM misconfigurations)
• Data exposure through unsecured APIs
• Overly permissive roles and credentials

Mobile App Penetration Testing

With mobile usage now surpassing desktop, attackers are shifting focus. Mobile app penetration testing specifically looks at mobile applications and the types of attacks that infiltrate their systems.

Mobile app pen tests identify:

• Data leakage risks
• Insecure storage practices
• Weak authentication or session handling
• Vulnerable APIs and third-party SDKs

IoT and Embedded Device Testing

From smart cameras to industrial controls, IoT is everywhere, and it’s often highly targeted and poorly secured.

IoT pen testing examines:

• Firmware vulnerabilities
• Default or hardcoded credentials
• Unencrypted communications
• Remote access flaws

This is key if you’re in the manufacturing, healthcare, or logistics sectors and utilise IoT devices in your operations.

Specialised Testing Approaches

There are countless methods to penetration testing, but to make things a bit simpler, you should always look to choose a provider that follows current industry standards. The penetration testing tools and techniques used by each provider will be slightly different, but here are some of the most common approaches.

Physical Penetration Testing

A penetration test of your physical premises is a red team exercise.

This involves simulated break-ins or tailgating attempts to access secure areas, USB drops, and more.

It’s ideal for data centres or offices storing sensitive hardware.

Social Engineering Tests (Phishing, Pretexting)

Phishing and similar social engineering attacks are still the number 1 cause of data breaches and are responsible for 98% of successful cyberattacks. Social engineering pen testing simulates phishing emails, pretext phone calls, or USB baiting to see how your staff respond, and where human error might expose your systems.

Red Team vs. Blue Team Exercises

Red Team exercises simulate a full-scope, stealth cyberattack, often mimicking the tactics, techniques, and procedures (TTPs) used by real world hackers to test your defences. The Red Team operates like a determined adversary, attempting to breach systems, bypass security controls, and access sensitive data without detection. A red team will typically stop when a breach occurs, depending on the scope, so it doesn’t necessarily uncover all current vulnerabilities.

Blue Team refers to your defensive security, typically your IT, Security Operations Centre (SOC), or incident response teams, responsible for detecting, containing, and responding to attacks in real time.

These exercises are designed to go beyond traditional penetration testing. Instead of focusing on finding a range of vulnerabilities, they assess:

• How well your people, processes, and technology can detect and respond to active threats
• Your organisation’s ability to coordinate during an ongoing attack
• Escalation procedures, incident reporting, and containment strategies
• How long attackers can remain undetected (dwell time)

They’re particularly valuable for maturing your security operations and improving response times, especially when combined with Purple Teaming, where both Red and Blue Teams collaborate to strengthen defences.

For UK organisations operating in critical sectors such as finance, healthcare, and national infrastructure, Red Team exercises also support compliance with frameworks like DORA, NIS2, and ISO 27001 Annex A.5 and A.16.

DigitalXRAID’s Red Team services are tailored to emulate advanced persistent threats (APTs), often using custom tooling, social engineering, and lateral movement, to help you build confidence in your ability to detect and contain even the most sophisticated cyberattacks.

SCADA and ICS System Testing

If you’re a critical infrastructure operator in a sector such as energy, transport, or manufacturing, you will likely rely on SCADA or ICS systems, which are often outdated or unpatched.

This specialised pen test helps to uncover weaknesses in protocols like Modbus or DNP3, as well as physical access or insecure remote management.

Penetration Testing Methodologies: Black Box, White Box, Grey Box

Not all tests start from the same point of access. The penetration testing methodologies you use will depend on your goals. There are typically three main methods of penetration testing used by specialists:

What is Black Box Penetration Testing?

Black box penetration testing is arguably the most true to life form of penetration testing. It involves a team with no prior knowledge of a business’s cyber infrastructure carrying out a penetration test to determine the strength of the overall security posture.

It simulates an external attacker’s view and is ideal for:

• Perimeter defence assessment
• Cloud-hosted or third-party facing applications
• Regulatory testing such as PCI DSS

At DigitalXRAID, our black box engagements emulate real world threat scenarios, gathering intelligence using public data, scanning for vulnerabilities, and exploiting weaknesses wherever possible.

What is White Box Penetration Testing?

White box penetration testing, on the other hand, involves the testers having full knowledge of the target systems, and full visibility into the IT environment and source code. While this may be less realistic than black box testing, it allows for a high level stress test of your system’s security capabilities.

It’s ideal when:

• Assessing systems in development
• Conducting compliance audits
• Reviewing critical infrastructure or applications

Our white box pen tests go deep into your company’s infrastructure, combining static code analysis, configuration review, and manual testing to uncover even the most hidden vulnerabilities.

Grey Box Testing

Grey box penetration testing is something in between black box and white box testing. The testers can have partial or incomplete knowledge of the target systems, allowing for testing that both simulates a real world attack and provides an extremely thorough test.

This approach simulates an attacker who’s gained initial access or has insider knowledge.

Grey box testing is especially useful for:

• Privileged user risk assessment
• Lateral movement detection
• Zero Trust architecture validation

Choosing the Right Penetration Test for Your Organisation

With so many options, how do you know which type of penetration test is right for you?

Each type of penetration test and each approach to penetration testing has its advantages and disadvantages, but ultimately, it depends on your needs. At DigitalXRAID, we take your security goals into consideration before we determine which type of testing to proceed with. While we have expertise in all three areas, we may choose one over another for a variety of reasons. For example, if you are concerned about insider threats, we can use white box testing to better simulate that exact scenario.

Factors to Consider: Size, Industry, Risk Profile

• Regulated sectors: You should look at network + web app + phishing simulation
• Manufacturers: We suggest testing IoT, SCADA/ICS, and physical access systems
• Ecommerce or SaaS providers: Your regular testing should include web or mobile app and API
• Growing cloud-based organisations: You should regularly test your cloud environments and apps, particularly after any updates

Aligning Tests with Compliance and Information Security Frameworks

Many pen testing requirements are driven by compliance:

Framework/Regulation	Role of Pen Testing
ISO 27001	Supports A.12.6.1 (technical vulnerability management)
PCI DSS	Requires annual testing and after major changes
GDPR	Demonstrates Article 32 compliance
NIS2	Mandates proactive vulnerability management
DORA	Emphasises threat-led penetration testing for financial entities

Partnering with a Certified Testing Provider

There are a few easy methods you can use to evaluate a potential penetration testing solution, all of which make it that bit easier to find a provider you can actually trust.

First, find out whether or not the testing provider has any of the recommended penetration testing certifications. For example, a CREST, CHECK and NCSC certified provider would rank within the top 1% of security service providers globally, signalling a dedication to the highest level of security.

Look for:

• CREST certification – Verifies methodology and tester skills
• CHECK approval – Required for public sector testing
• ISO 27001 – Ensures secure handling of test data
• Proven results – Ask for case studies or references

As a CREST, NCSC and CHECK accredited provider, DigitalXRAID follows gold standard penetration testing methodologies to deliver actionable, compliance ready results, verified by an external accreditor.

How to Choose the Best Pen Testing Provider

Finding the right provider to carry out your penetration testing is crucial. You want to know that whoever you select has your business’s best interests at heart, is skilled enough to expose all vulnerabilities within your systems, and has the experience to provide you with the most comprehensive coverage.

So how do you choose the best pen testing provider for your business?

Examine the methodology used by your potential provider. Having no methodology at all should be a significant red flag, as it likely means the testing provided is not as rigorous or intensive as a real life cyber security attack would be.

The OWASP Top 10 is an extremely comprehensive standard that represents a broad consensus on what the current most critical security risks are to web applications. Penetration test providers should be using standards like these to form the base of their testing protocols in order to provide you with the best service possible for your business.

Most importantly, look at the experience of the penetration testing provider you’re considering working with. Do they have an extensive history of working with companies of all shapes and sizes? Does their track record speak to their history of stellar work? Have they received any awards for their efforts in protecting businesses from cyberattacks? All of these can let you know how strong a prospective provider’s credentials are for helping your business.

Final Thoughts: Strengthen Your Security with the Right Testing Approach

Penetration testing should be a core strategy for your company’s cybersecurity posture. Every organisation is different, and so are the cyber threats you face. Understanding the different types of penetration testing services gives you the insight needed to choose the right approach, comply with regulations, and stay ahead of attackers.

Working with a trusted provider is one of the best decisions you can make to protect your business, and at DigitalXRAID, we have the expertise and experience to provide a tailored solution that not only ensures you remain compliant with security standards but also resilient against even the most sophisticated attacks.

We’ll help you to uncover risks before attackers do. Whether it’s black box, white box or red teaming, our CREST and CHECK accredited experts are ready to test your systems and guide your remediation.

Need help choosing the right type of penetration test? Get in touch with our team to discuss your security goals and create a test tailored to your needs.

FAQs

What is the most common type of penetration test?

Network and web application tests are most widely used, especially for perimeter defence and customer-facing applications.

How often should penetration testing be conducted?

At least once a year, or after major infrastructure changes, new systems, or security incidents. Penetration testing is best used as a proactive measure to secure your organisation’s digital infrastructure. The frequency will depend on your organisation’s size, overall risk profile, how often updates are conducted, and the industry you work in.

What’s the difference between penetration testing and vulnerability scanning?

A vulnerability scan identifies known flaws in your cyber security. Penetration testing actively attempts to exploit those flaws to understand the real world impact a breach could have.

Is penetration testing required for ISO 27001?

Pen testing isn’t mandatory for ISO 27001, but it is strongly recommended to support Annex A controls and demonstrate proactive risk management.

Can social engineering be part of a pen test?

Yes. Phishing simulations, pretexting and USB drops are common elements of pen testing and Red Team exercises for human factor testing.

What is red teaming in penetration testing?

Red teaming refers to a simulated, multi layered attack that tests your people, processes, and technology under realistic threat conditions.

How long does a typical penetration test take?

Anywhere from a few days to several weeks, depending on your scope, the number of systems or IP addresses, for example, and the testing depth required.