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What is Penetration Testing (Pen Testing)?


Penetration Testing Definition

Penetration testing (pen testing) is a method that tests, measures, and improves the security measures of organizations' networks and systems by deploying the same tactics and techniques that a hacker would use. 

Pen tests enable organizations to test their IT systems, networks, and web applications for potential security vulnerabilities that could be exploited by an attacker. Penetration testers need to gather information about the system they test, identify potential entry points, and simulate an attack to understand organizations’ vulnerability to threats like malware and ransomware.

Penetration tests aim to discover and report weaknesses in an organization’s security posture. They test security policies, compliance with data and privacy regulation requirements, such as the Payment Card Industry Data Security Standard (PCI DSS), and the ability of the organization and its employees to discover and respond to incidents.

Benefits of Penetration Testing

The information gleaned from a pen test helps IT and network managers understand their security weaknesses and make strategic decisions to remediate them. A pen test report provides an organization with insight into how to prioritize its cybersecurity investments and how to create and develop secure web applications.

Types of Penetration Testing

There are three methods of managing penetration tests that simulate cyberattacks.

Black Box

Black box pen testing simulates an attempted hack that comes from outside of an organization. The test begins with the pen tester receiving no information about the organization’s networks or systems.

Gray Box

A gray box pen test focuses on high-value areas of a network. They can often simulate a situation where an attacker has penetrated an organization’s perimeter and has some level of access to their internal network.

White Box

A white box pen test replicates a hacking attempt that comes from inside the organization. It sees pen testers simulate being a malicious insider that has knowledge of how the organization’s systems are set up.

Phases of Penetration Testing

Pen testing is a five-phase process:


The first stage is to define and plan the scope and goals of the test. This includes the systems that need to be addressed and the pen testing methods that need to be used. Pen testers gather intelligence about the organization’s network to better understand how it works and its potential vulnerabilities.


With the planning stage completed, the pen tester needs to analyze the application they are testing to understand how it will respond to intrusion attempts. They do this through static analysis, which inspects application code to estimate how it will behave while running, and dynamic analysis, which inspects the code in real time or in a running state.

Gaining Access

The pen tester will then use web-based attacks, such as cross-site scripting (XSS) and Structured Query Language injection (SQLi), to discover and exploit vulnerabilities. This involves escalating their privileges, intercepting traffic, and stealing data to understand the level of damage an attacker could cause.

Maintaining Access

This stage assesses whether the discovered vulnerabilities can be used to gain continued presence in the organization’s system and the level of access they can achieve. This is aimed at imitating advanced persistent threats (APTs), which enable an attacker to linger in a network for months and steal highly sensitive data.


The results of the test are compiled to detail the vulnerabilities exploited, any sensitive data that pen testers were able to access, and the amount of time they could remain in the organization’s system.

Types of Penetration Testing Tools

Pen tester electrical events use a variety of pen testing tools to plan and carry out a penetration test.

Learn the different types of penetration testing tools

Reconnaissance Tools

Penetration testing begins with reconnaissance tools, which collect information about the application or network being targeted. Reconnaissance tools include port scanners, web service reviews, and network vulnerability scanners.

Vulnerability Scanners

Vulnerability scanners help pen testers identify applications with known vulnerabilities or configuration errors. They can be used to help a pen tester select a vulnerability to initially exploit.

Proxy Tools

Web proxy tools enable pen testers to modify and intercept traffic between their browser and the organization’s web server. This allows them to identify and exploit vulnerabilities in an application through techniques like XSS and cross-site request forgery (CSRF).

Exploitation Tools

Exploitation tools are used to attack an organization in a pen test. They include software that can produce brute-force attacks or SQL injections, social engineering techniques, and hardware designed specifically for pen testing, such as boxes that plug into a device and provide remote access to networks. 

Post-exploitation Tools

Upon the completion of a test, the pen tester uses post-exploitation tools to cover their tracks. This includes removing embedded hardware and taking measures to avoid detection while leaving the system how they found it.

Penetration Testing vs. Automated Testing

Until recently, only trained ethical hackers could take on manual penetration tests. However, automated testing is increasingly replacing or complementing this approach.

Manual Penetration Testing

Manual pen testing or true penetration testing is the traditional method for identifying flaws in applications, networks, and systems. It involves techniques that check whether organizations are secure from sniffing and data interception attacks, which might target the secure sockets layer (SSL).

Automated Testing

Automated testing is the use of tools and technology like artificial intelligence (AI) to scan potentially vulnerable areas of networks and autonomously simulate an exploit. The findings are automatically compiled in a report. This is becoming popular because traditional tools can fail to detect complex vulnerabilities and weaknesses.

Pros and Cons of Penetration Testing

Pros of Penetration Testing

Finds Holes in Upstream Security Assurance Practices

Pen testing enables organizations to discover a wide range of issues in their networks and systems. Some may be small issues that, in isolation, may appear minor but could enable an attacker to build a wider attack. Pen testing is crucial to finding holes in security practices and policies.

Locates Both Known and Unknown Software Flaws

A pen test enables organizations to pinpoint flaws they knew about and discover new vulnerabilities that could be hugely costly if exploited by a cyber criminal.  

Can Attack Any System

Pen testers gain full access to an organization’s network, enabling them to discover vulnerabilities that may have been overlooked by IT or security teams. They can test all areas of corporate systems and identify any potential point of entry.

Cons of Penetration Testing

Labor-intensive and Costly

Running a pen test can be an expensive process, especially since the tests must be carried out on a regular basis. It also demands an organization to put a huge amount of trust in the pen tester not to abuse their knowledge, skills, and level of access to corporate information.

Result in Bugs and Flaws

An ineffective penetration test can result in crashed servers, sensitive data being exposed, and data being corrupted. It is also important to use realistic test conditions and avoid preparing for a pen test, which will only make the organization weaker to real-life attacks.

3 Best Practices of Penetration Testing

  1. Include All Data Sources: Penetration testing needs to be full-scale and comprehensive. Include all data sources that contain any valuable, especially sensitive, or personal information.  
  2. Follow a Methodology: There are many different approaches to penetration testing. Understand the different tools methodologies available so you can choose one to follow.
  3. Communicate Actively: You need to have a communication plan so your team can monitor progress, ask questions, and exchange critical information along the way.

How Fortinet Can Help?

The Fortinet FortiPenTest is a cloud-native Pen Testing-as-a-Service (PTaaS) tool that enables organizations to discover potential vulnerabilities before they are exploited by attackers. The Fortinet pen test tool is based on the FortiGuard pen test team's insight into how to test networks for vulnerabilities that detail issues an organization faces and how they can mitigate them.

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What Is penetration testing or pen testing?

Penetration testing (pen testing) is a method that tests, measures, and improves the security measures of organizations' networks and systems by deploying the same tactics and techniques that a hacker would use. 

What are the three types of penetration testing?

There are three methods of managing penetration tests that simulate cyberattacks.  Black Box, Gray Box, and White Box.  

What are the benefits of Penetration Testing?

The information gleaned from a pen test helps IT and network managers understand their security weaknesses and make strategic decisions to remediate them.