6 types of penetration testing & which is best for your business

Penetration testing helps you find weaknesses in your systems before attackers do, but the type of test you need depends on what you're trying to protect. This guide breaks down the most common types, from network and web app testing to AI pentesting, so you can choose the right approach for your environment.

TL;DR of the different types of penetration testing

1. Network penetration testing: The most common and crucial type of penetration test
2. AI pentesting: Uses autonomous AI agents to perform penetration tests on-demand
3. Web application penetration testing: For uncovering vulnerabilities across websites and web applications
4. Cloud penetration testing: For testing the security posture of your cloud environment
5. Social engineering pen tests: For testing the resilience of your personnel to social engineering attacks (e.g. phishing assessments)
6. Red teaming: An advanced assessment that can take months to complete

What is penetration testing?

Penetration testing, commonly referred to as “pen testing”, is a technique that simulates real-life attacks on your IT systems to find weaknesses that could be exploited by hackers. These assessments are carried out by penetration testers or 'ethical hackers'.

Whether to comply with security regulations such as ISO 27001, gain customer and 3rd party trust, or achieve your own peace of mind, penetration testing is an effective method used by modern organizations to strengthen their cybersecurity posture and prevent data breaches.  

How often should pen testing be conducted?

Due to the complexity and cost of a traditional penetration test, most organizations only carry one out annually. That leaves long gaps between assessments where new vulnerabilities can go undetected.

AI pentesting is changing this. Because tests can be triggered on-demand and results are delivered within hours, organizations no longer have to wait months between assessments. This makes it practical to test more frequently, whether that's after a major release, ahead of an audit, or as part of a regular testing cadence throughout the year.

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6 types of pen testing to strengthen cybersecurity

The type of penetration testing you need depends on your unique IT environment. We have summarized the most common types to help you find out which you would benefit from the most.

1. Network penetration testing

As the name suggests, a network penetration test aims to identify weaknesses in your network infrastructure, be that on the premises or in cloud environments. It is one of the most common and crucial tests to perform to ensure the security of your business-critical data.

Network penetration testing covers a broad range of checks, including insecure configurations, encryption vulnerabilities, and missing security patches in order to determine the steps a hacker could take to attack your organization. Security professionals often categorize network penetration tests into two different perspectives: external and internal penetration testing.

External penetration testing

External penetration testing involves searching for vulnerabilities that could be exploited by any attacker with access to the internet.

In this type of network penetration test, penetration testers are trying to get access to your business-critical systems and data in order to determine how an attacker without any prior access or knowledge would be able to target your organization.

You can think of an external penetration test as being performed from the perspective of an "outsider".

Internal penetration testing

In contrast, internal penetration testing is concerned with testing your internal corporate environment.

This type of pen testing considers scenarios in which an attacker has managed to gain an initial foothold within your corporate network, for example by exploiting a vulnerability in one of your internet-facing systems, or through the use of social engineering.

In this case, the test is performed from an “insider” perspective, with an objective of finding a way to steal sensitive information or disrupt the operations of an organization.

When to carry out network penetration testing

External network penetration testing is the first type of penetration testing organizations usually perform. Generally speaking, external weaknesses are considered to pose a more serious threat than internal. For one thing, a hacker has to overcome an external security barrier before accessing your internal networks and pivoting to other systems.

If you haven't conducted any kind of penetration testing before, an external or “perimeter” test is often the best place to start, as the perimeter is the easiest thing for attackers to get to. If you have trivial vulnerabilities in your internet-facing infrastructure, that's where the hackers will start.

2. AI pentesting

AI pentesting uses autonomous AI agents to perform penetration tests in a similar way to a human pentester. Rather than working through a fixed checklist of known vulnerability types, the agents reason through an application's behavior, identify vulnerabilities, test attack paths, and validate that findings are genuinely exploitable.

This differs from traditional vulnerability scanning or DAST (Dynamic Application Security Testing), which can only detect known types of vulnerabilities. AI pentesting reasons through how the application is supposed to behave, meaning it can catch things like broken business logic or missing access controls that these tools would miss.

An AI web app pentest typically runs through several stages. It starts with scoping, where you define the target application and provide access. The agent then maps the application's endpoints, user journeys, and functionality before searching for vulnerabilities in the code. Any candidate findings are validated by exploiting them against the application to confirm they're genuine, so what gets reported has already been proven exploitable. From there, findings are prioritized and delivered in a report.

AI pentesting also excels at catching multi-step vulnerabilities, where several smaller issues chain together into something more serious. These can be time-consuming to test for manually, because tracking how one step influences the next across a large application is difficult to do by hand. The same applies to authorization issues like Insecure Direct Object References (IDORs), where a missing ownership check in one part of a codebase can easily go unnoticed during a manual review. Read our full explainer on AI pentesting.

When to carry out AI pentesting

AI pentesting makes sense when you want to test more often than manual engagements allow. You get the depth of a pentest on demand, without the cost or scheduling overhead, so testing can keep up with how often you ship.

3. Web application penetration testing

Web application penetration testing attempts to uncover security vulnerabilities across websites and web applications, such as e-commerce platforms, content management systems, and customer relationship management software.

This type of pen test deals with reviewing the entire web application's security, including its underlying logic and custom functionalities, to identify vulnerabilities and prevent data breaches.  

Some of the common vulnerabilities detected during a web app penetration test include database injections, cross-site scripting (XSS), and broken authentication.

If you are interested in learning more about different types of web application weaknesses, their severity and how you can prevent them, the Open Web Application Security Project (OWASP) Top 10 is a great place to start. Every few years OWASP publishes information about the most frequent and dangerous web application flaws, basing its findings on the data collected from many thousands of applications.

When to carry out a web application penetration test

Considering the prevalence of web applications in modern organizations, and the valuable information that they transmit and store, it is unsurprising that they are an attractive target to cybercriminals. A report found that almost one-in-ten vulnerabilities in internet-facing applications are considered high or critical risk.

For this reason, any organization that is developing or managing their own internet-facing applications should strongly consider conducting web application penetration testing as part of their web app security testing program.

4. Cloud penetration testing

In a cloud penetration test, the tester will start with no access to the cloud environment or limited access if they're testing an assumed breach scenario – for example assuming an attacker has compromised a server in the cloud environment, or a specific user. They'll then try to escalate their privileges to reach other parts of the cloud environment, trying to access sensitive data.

Different manual methods (such as black box penetration testing vs gray box penetration testing) may be used, depending on the type of cloud service and the provider. However, since you don't actually own the cloud infrastructure, platform or software as an entity but rather as a service, there are strict legal restrictions and technical challenges to cloud penetration tests.

As a cloud user, your focus is on ‘security in the cloud' and not ‘security of the cloud'. What you are responsible for, and therefore what can be included in the scope of a pentest, is dictated by the shared responsibility model.

When to carry out cloud penetration tests

Businesses often won't have in-house cloud or security experts when they start their shift to cloud services. This means teams might be quickly and unknowingly creating security holes that are hard to monitor and fix. A cloud penetration test would give you in-depth insight into your cloud security posture to help you verify whether your ongoing vulnerability management efforts are working.

5. Social engineering pen tests

In comparison to previously described penetration testing types, which focus on finding weaknesses in technology, social engineering attempts to compromise the security of an organization by exploiting human psychology.

It can take a variety of forms and could be executed both remotely, for example by trying to obtain sensitive information from users through phishing emails or phone calls, or on-site, in which case a penetration tester will attempt to gain access to a physical facility (otherwise known as 'physical penetration testing'). In all cases, the objective of this penetration test is to manipulate individuals, usually the company's employees, into giving away valuable information.

The success of a social engineering penetration test largely depends on the information gathered in the “reconnaissance” phase, which involves researching targeted individuals or an organization by using publicly accessible open source intelligence (OSINT).

After building a more precise image of their target, a penetration tester can use discovered information to proceed with the creation of a tailored attack strategy.

One of the most common attack vectors in social engineering is a phishing attack, usually delivered by email. When performing a phishing attack, a penetration tester does not necessarily stop when an unsuspecting employee clicks on a malicious link, but can go further, attempting to steal user credentials and get access to an employee's laptop.

Such attacks can be extremely successful, especially when performed by experienced penetration testers. Take a look at some phishing attempts made against the Intruder team.  

When to carry out social engineering penetration testing

Social engineering penetration testing is not as widely adopted as network or web application testing. However, if your organization is already doing regular security awareness training, conducting social engineering tests can be a great addition to your arsenal for identifying and fixing security issues in your operations.

6. Red teaming  

This advanced technique has its origin in military training exercises. It is designed to challenge an organization's security, processes, policies and plans by adopting an adversarial mindset.

In contrast, Blue Teaming, otherwise known as “defensive security”, involves detecting and withstanding Red Team attacks as well as real-life adversaries.

Red Teaming combines digital, social and physical domains to implement comprehensive real-life attack scenarios. As such, Red Teaming can be considered a distinct operation from penetration testing, but since its tasks span all of the types of penetration testing described above, we thought it was worth mentioning it in this article.

An objective of a standard penetration test is to find as many vulnerabilities as possible within a given timeframe. The breadth of this test is naturally limited by the scope of work; but real-life adversaries don't have such artificial restrictions to follow.

As a result, even if an organization regularly performs penetration tests and vulnerability scans, it can still be exposed to more sophisticated attacks such as those where social engineering and internal network weaknesses are chained together.

This is where Red Teaming comes in. It assesses an organization's environment as a whole, understanding how all parts function together. It then applies critical thinking to discover new vulnerabilities that attackers can exploit, helping the organization to assess its response to real-world attacks.

When to carry out a red team assessment

Compared to the standard penetration test, which lasts several days or weeks, Red Team assessments generally take much longer, in some cases several months to complete.

Due to its complex nature, it is a rather rare operation, typically performed by larger organizations or by government contractors with well-established security programs.

Black box vs Gray box vs White box pen testing methods

You may have heard of terms like "black box penetration testing", "gray box penetration testing", and "white box penetration testing". These terms are supposed to refer to the amount of information shared with testers prior to an engagement. For example, source code is "typically" provided in white box penetration tests, but not in black box pen tests.  

The problem with these terms though is that there is no strict definition of what they mean, so often as soon as a client asks if you can do a white box penetration test the immediate follow-up question is, sure, but what information do you want to include? At which point, you might as well just define what information will be provided anyway without these vague terms, since no penetration test is really conducted on zero information.  

The rationale behind these terms is that you might want to understand what someone can figure out on their own without any information. That might be a valid instinct, but it's worth questioning this mindset.

There's a saying in cybersecurity that “obscurity is not security” - which means you shouldn't hope that something is secure just because someone doesn't know or can't guess something.

A pentester armed with more information might be very quickly able to tell you that something isn't secure, while an uninformed one might take way longer to figure it out. And guess what – you're the one paying for their time.

So while we wouldn't say "scenario" type pen tests are never right, it's worth thinking about why you are doing it and what you really want from the exercise. Do you want to be more secure, or do you want to see how long it takes someone to figure it out?  

A good pentesting company will usually help guide you by asking for the information that makes the most sense for the budget you have available, or the scenario you're asking them to test.

To conclude

The right type of penetration test depends on your environment, your risk profile, and what you're trying to protect. If you need help getting started, we've written guides on what to look for (and avoid) when choosing a pentesting company and the best AI pentesting tools.

Intruder's AI pentesting gives you the depth of a manual pentest, on-demand. No procurement cycle, no lead times, and results delivered in hours. See pricing or book a demo to get started.

Thanks to Daniel Thatcher (Intruder Security Research Engineer)‍