What is penetration testing and how does it work?

By Nitin Dhiman · Published on October 12, 2026

Penetration testing, also known as pen testing, security pen testing, and security testing, is a form of ethical hacking. It describes the intentional launching of simulated cyberattacks by “white hat” penetration testers using strategies and tools designed to access or exploit computer systems, networks, websites, and applications. Although the main objective of pen testing is to identify exploitable issues so that effective security controls can be implemented, security professionals can also use penetration testing techniques, along with specialized testing tools, to test the robustness of an organization's security policies, its regulatory compliance, its employees' security awareness, and the organization's ability to identify and respond to security issues and incidents such as unauthorized access, as they occur. As a simulated cyberattack, ethical hacking techniques help security professionals evaluate the effectiveness of information security measures within their organizations. The pen test attempts to pierce the armor of an organization’s cyber defenses, checking for exploitable vulnerabilities in networks, web apps, and user security. The objective is to find weaknesses in systems before attackers do. Penetration testing, also called pen testing, is a cyberattack simulation launched on your computer system. The simulation helps discover points of exploitation and test IT breach security. By doing consistent pen testing, businesses can obtain expert, unbiased third-party feedback on their security processes. Though potentially time-consuming and costly, pen testing can help prevent extremely expensive and damaging breaches. Penetration testing (also called pen testing) is the most efficient way to discover and eliminate real-world potential vulnerabilities that lead to cyber attacks and data breaches. Penetration testing basically means that an ethical hacker performs a simulated attack and attempts to gain access to resources that they should not have access to or perform operations that they should not be able to perform. If successful, the penetration tester explains how it was done so that developers can fix the security vulnerability before a black hat hacker exploits it. However, penetration testing must be performed by security experts. Security professionals who are skilled enough in ethical hacking to do pen testing are rare and valuable. If pentesters focus on basic security testing, they have no time to discover all security vulnerabilities.

A pen test can be automated using security tools or it can be performed manually. In order to provide insights critical to the organization’s ability to fine-tune its security policies and patch detected vulnerabilities, penetration tests need to expose vulnerabilities that would allow attackers system access. The process involves gathering information about possible targets, identifying potential entry points, attempting to break in – either virtually or actually – and reporting back findings to the organization’s security team.

As a simulated cyberattack, ethical hacking techniques help security professionals evaluate the effectiveness of information security measures within their organizations. The pen test attempts to pierce the armor of an organization’s cyber defenses, checking for exploitable vulnerabilities in networks, web apps, and user security. The objective is to find weaknesses in systems before attackers do.

In the case of networks, the high-level goal is to strengthen security posture by closing unused ports, troubleshooting services, calibrating firewall rules, and eliminating all security loopholes.
In the case of web applications, pen testing is designed to identify, analyze, and report on common web application vulnerabilities such as buffer overflow, SQL injection, cross-site scripting, to name just a few.
Pen testing can also be used to attempt to gain privileged access to sensitive systems or to steal data from a system that is believed to be secure.

Common Pen Testing Strategies

Based on the objectives of the organization, here are some commonly used penetration testing strategies:

External testing: This involves attacks on the organization's network perimeter using procedures performed from outside the organization's systems, e.g., the Extranet and Internet.
Internal testing: Performed from within the organization’s environment, this test attempts to understand what could happen if the network perimeter were successfully penetrated or what an authorized user could do to penetrate specific information resources within the organization's network.
Blind testing: In this case, the tester tries to simulate the actions of a real hacker. The testing team has little or no information about the organization but instead must rely on publicly available information (such as corporate website, domain name registry, etc.) to gather information about the target and conduct its penetration tests.
Double-blind testing: In this exercise, only a few people within the organization are made aware of the testing. The IT and security staff are not notified or informed beforehand, and as such, they are "blind" to the planned testing activities. Double-blind testing helps test an organization's security monitoring and incident identification processes, as well as its escalation and response procedures.
Targeted testing: Also known as the lights-turned-on approach, target testing involves both IT and penetration testing teams. Testing activities and information concerning the target and the network design are known going in. Targeted tests require less time and effort than a blind test, but typically don’t provide as complete a picture of an organization's security vulnerabilities and response capabilities as other testing strategies.

Manual or automated

Pen testing can be performed manually or it can be automated. Pen testing using automated testing tools optimizes resources by automating elements of the penetration testing process so vulnerability identification can be performed continuously and without human intervention. In order to provide insights critical to the organization’s ability to fine-tune its security policies and patch detected vulnerabilities, penetration testing needs to expose security flaws that would allow attackers user, system, network, or application access. The process involves gathering information about possible targets, identifying potential entry points, attempting to break in – either virtually or actually – and reporting back findings to the organization’s security team. With so many moving parts, automated testing tools save time and typically produce better penetration test results than manual efforts. Costly breaches, loss of data, compromised systems, users, and applications – these are all things that bring high risk to the enterprise. Pen testing, particularly automated pen testing, can be a very effective tool to help prevent real-world attacks and mitigate these kinds of vulnerabilities. They also deliver fewer false positives and lower AppSec costs.