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What Is Penetration Testing?

Patrick Sullivan

ethical hacking group

Regular security testing is key to keeping your digital assets safe and secure. You’ll need to find and fix your system’s digital vulnerabilities before hackers do in order to keep your systems safe.

One particularly important type of security testing is penetration testing. Often shortened to “pen testing,” this cybersecurity strategy involves conducting a simulated attack on your system using the same strategies that real-world cyber criminals use.

By conducting your own cyber attack, it’s easier to identify where your security weaknesses are and make changes to address the problem. Think of it as a stress test for your cybersecurity system. There are many penetration testing tools on the market to ensure that no stone is left unturned when it comes to your network security.

Here’s everything you need to know about penetration testing processes and strategies for your organization.

Key Takeaways

  • Penetration testing is the process of finding and exploiting security vulnerabilities within a target system or web application.
  • The process of penetration testing is lengthy and includes information gathering, vulnerability analysis, exploitation, and analysis.
  • The results of a penetration test can be used to inform future changes and improvements in your security systems.
  • Penetration tests address many different types of threats, ranging from social engineering threats to injection attacks and more.
  • Penetration tests can be performed in-house or outsourced to a third-party firm or consultant.

How Does Penetration Testing Work?

Penetration testing isn’t simply a matter of launching attacks against systems to find their weak spots. It’s a structured, methodical process that requires extensive planning in order to succeed. The penetration testing market is growing rapidly as organizations are realizing the importance of protecting their systems. In 2021, the pen testing market was valued at $1.87 billion, and is expected to reach $5.28 billion by 2028. 

The test itself involves finding and exploiting many different vulnerabilities to get a comprehensive look inside your security system. The process doesn’t stop after the test is completed – you’ll need to conduct an in-depth analysis to understand why security issues are happening and what you need to do to fix them.

Pre-Engagement Phase

The first step in any penetration test is to clearly define the goals and scope of the test. This step ensures that everyone involved knows what will happen during the test and what to expect.

You’ll need to concretely identify which systems you want to test, as well as the methodologies you plan to use during the test. On top of that, you’ll need to set goals for the process, which will help you determine whether or not your test was successful and how to move forward after it is complete.

You’ll also need to obtain explicit permission from all relevant parties involved. This ensures that the test remains ethical and professional. If you don’t have an agreement in place prior to your pen test, you could encounter legal issues later on.

Intelligence Gathering

Before launching the attack, the penetration testers will gather as much information as possible about the target system. This includes passively gathering information about the target from the internet as well as actively interacting with the system.

During this phase, testers will often conduct scans of the network infrastructure to look for potential firewall vulnerabilities and other issues to exploit during the test. This information stage helps penetration testers conduct their tests as efficiently as possible.

Threat Modeling and Vulnerability Analysis

Once a significant amount of data has been collected about the target, the next step is to identify potential threats and vulnerabilities. This step ensures that nothing goes unaddressed during the testing process.

Security tools like vulnerability scanners are often used in this process. After you identify where the vulnerabilities are in your system, you’ll need to map out what might happen in real-world attacks to inform your tests.


During the exploitation phase, the system is finally tested for security vulnerabilities. The penetration test will attempt to exploit vulnerabilities they’ve found during the initial analysis. They will focus on the goals defined during the initial pre-engagement phase and look for ways to gain unauthorized access to the system.


After the test is complete, the penetration tester will document their findings with a detailed report outlining the vulnerabilities they successfully exploited, what type of data they accessed, and how long they were in the system. The tester will also provide suggestions on how to move forward and address these issues.

After receiving this documentation, your security team will need to conduct remediation to improve your security. Keep in mind that you’ll likely need to conduct multiple rounds of penetration testing and continuously improve your security measures over time. 

Hackers are consistently developing new strategies as technology changes, and you’ll need to adjust your systems to address them.

Stages of Penetration Testing

The penetration testing process can be broken down into five main stages. These stages make the testing process more accessible and efficient.

1. Reconnaissance

This is the information-gathering stage. During this stage, the tester will search for as much information as possible about the target.

The reconnaissance process can vary depending on the type of system you’re testing and the goals of the test. In a black box penetration test, the testers won’t have access to any internal information about the target system. This means that the reconnaissance phase will focus mainly on collecting information through the internet.

With other forms of pen testing, the hacker will have more information about the target system. In a gray box test, testers have access to some of the internal structures or credentials. In a white box test, testers have access to the entire system, including source code.

With these types of tests, the reconnaissance process requires testers to work much more collaboratively to get access to the security controls they need.

2. Scanning

The next step in the testing process is conducting vulnerability scans using pen testing tools. This can be done while the target web application is running or while it is static. Scanning tools will identify potential vulnerabilities to focus on in the later stages of testing.

3. Gaining Access

After completing a vulnerability assessment and deciding what to focus on, the next step is to gain access to the target network, web apps, or computer system. There are many ways to do this, whether it be through an SQL injection, social engineering tactics like phishing, or even through malware. 

These ethical hacking techniques mimic the approaches that cyber criminals use.

4. Maintaining Access

Gaining access to target systems is just the first step of the test. The next step is to maintain access long enough to exploit sensitive data or cause other damage to your systems.

This is necessary because it takes time for hackers to fully breach your system. In some cases, it can take weeks or even months for hackers to cause damage. It’s important to understand what that timeline looks like for your system so you can adjust your security standards as needed.

5. Analysis and Reporting

After the test is complete, the tester will put together a detailed report of what happened during the test, as well as an analysis of their findings. This report will help the end client make adjustments to the target system to minimize vulnerabilities and better understand how your system works.

Methods and Techniques

There are many different types of pen testing that security professionals and ethical hackers use throughout this process. The exact methods and techniques used will depend on the type of system you’re testing and the goals of the testing process.

Network Penetration Testing

This approach focuses on finding vulnerabilities in an organization’s network infrastructure. When these networks are compromised, it provides an opportunity for hackers to compromise internal systems and access sensitive data. 

In the worst case scenario, hackers could even take over your systems for malicious purposes. Network penetration testing focuses on preventing these situations from happening. 

Below are a few different strategies that security experts use for network testing.

Vulnerability Scanning

During this automated process, testers use specialized tools like Nessus, OpenVAS, or Nexpose to identify potential vulnerabilities in the network. These tools scan for things like outdated software, configuration errors, and security patches that haven’t been installed. This results in a quick overview of weak spots an attacker could potentially exploit.


There are a variety of different strategies that pen testers can use to exploit these vulnerabilities. These must all be done ethically with prior permission from the client. This could involve injecting malicious code, bypassing existing security measures, or establishing a backdoor for easy access. Tools like Metasploit are often used during this step.

Password Cracking

Strong passwords are vital to the security of any network, which is why password cracking is often involved in network penetration testing. There are a variety of different ways to crack user passwords, including brute force attacks, dictionary attacks, and rainbow table attacks. This is an efficient way to identify weak passwords and enforce a robust password policy.

Web Application Penetration Testing

Organizations will often conduct penetration testing on specific web applications, particularly if they are often targeted by hackers. This type of testing focuses on vulnerabilities in the application’s code and configurations, and it uses different strategies from network penetration testing. 

Here are a few of the vulnerabilities testers look for in this type of testing.

Injection Attacks

Web applications are particularly vulnerable to injection attacks, so they are always addressed during penetration testing. During an injection attack, the hacker uses data to manipulate the application to produce a desired result.

The most common type of injection attack is the SQL injection, which is when hackers put malicious code into user forms in an application. However, there are many other types of injection attacks as well.

Cross-Site Scripting (XSS)

Cross-Site Scripting (XSS) is a type of security vulnerability often found in web applications. XSS gives attackers the opportunity to inject malicious scripts into web pages for their own gain.

These scripts give hackers a way to steal user cookies, deface web sites, or redirect the user to a malicious website, for example. Penetration testers look for XSS vulnerabilities and will suggest appropriate security measures to prevent them, such as implementing a stronger content security policy.

Cross-Site Request Forgery (CSRF)

Cross-Site Request Forgery (CSRF) is another common web application attack that tricks victims to submit malicious requests to the application. The attack finds a user who is logged into the app, and uses their browser to send a forged HTTP request to the application. 

This allows the hacker to access the application through the victim’s authenticated profile and potentially compromise internal data.

Social Engineering

Today’s systems are highly vulnerable to social engineering, which is when hackers use a variety of social strategies to trick users into sharing passwords, financial information, intellectual property, and other sensitive data. 

Here are a few common forms of social engineering that are typically addressed during penetration testing.

Phishing Attacks

Phishing attacks are very common and can be very dangerous. This typically involves sending emails, text messages, or social media messages that appear to come from a reputable source in order to trick victims into revealing sensitive information. 

Penetration tests often include simulated phishing attacks to determine whether or not team members need more security awareness training.


Pretexting is another form of social engineering where attackers create a fabricated scenario or pretext to obtain personal or financial information. For example, they might pose as a coworker, bank official, or even a government official. Attackers will often pretend to need pieces of personal information in order to “confirm the victim’s identity.”

Physical Security Breaches

While often overlooked, physical security is a crucial aspect of any organization’s overall security posture. Many social engineering strategies involve some type of physical security breach, such as following someone into a secure area or manipulating secure devices in person.

Who Can Perform Penetration Testing?

There are many different types of individuals who can perform penetration testing. However, it’s important to make sure that the process is carried out by trained security professionals who have a deep understanding of cybersecurity.

In-House Security Teams

Many organizations have their own in-house cybersecurity teams who can conduct penetration tests. These teams have deep knowledge of the organization’s systems, which can be an advantage when conducting tests. However, they might also overlook certain vulnerabilities due to their familiarity with the system or because of resource constraints.

Third-Party Security Firms

Many third-party security organizations offer penetration testing services to their clients. The benefit of working with a third-party firm is that they offer an unbiased approach, are typically up-to-date with the latest security threats, and have plenty of resources available to conduct penetration testing.

Independent Security Consultants

Independent security consultants are individuals with specialized cybersecurity skills who work with clients on a freelance basis. These consultants offer many of the same benefits as third-party security firms, and can sometimes offer an even higher level of expertise and personalized attention. However, since they are working individually, they may sometimes have limited testing resources.

Ethical Hackers

Ethical hackers, also known as white hat hackers, are cybersecurity professionals who use their skills to help improve system security rather than exploit it. 

They understand the tactics and techniques that malicious hackers use, and this knowledge is extremely valuable for penetration testing. Ethical hackers can be part of an in-house team, a third-party firm, or work as independent consultants.