Penetration Testing: Definition, Stages and Types

Online users who struggle to understand what penetration testing is are not alone. Plenty of other people who are new to the field of cybersecurity find terms such as penetration tests and ethical hacking rather confusing.

Ethical hackers are hired to try to invade a system to understand what are the security weaknesses. There are many types of penetration testing with different targets and techniques. That’s why pen testers plan beforehand what are the stages of penetration testing. Penetration testing helps organizations in preventing data breaches, complying with security regulations and improving reputation.

Penetration Testing Definition

What Is Penetration Testing?

Penetration testing refers to the simulation that is launched on a test device to discover all security vulnerabilities areas that skilled hackers could exploit and check a system or network’s IT breach security.

Penetration testing also refers to the procedure used to evaluate an organization’s security posture. Penetration testing is a perfectly legal exercise and is sometimes even required by organizations and regulatory authorities.

Almost all modern companies, organizations and enterprises have systems that are connected to the internet. Penetration testing is simulating an attack on such systems and any security infrastructure that the company has invested in. Such infrastructure includes users, applications and the network. With the help of procedures that are designed to root out the weak points of any security system or network, organizations can know detailed answers to tough questions regarding data security and user privacy.

What Is the Purpose of Penetration Testing?

The primary purpose of any penetration testing exercise is to find security weaknesses in a device, application or network. Penetration testing is important because only through such testing can organizations identify weak spots, maintain current systems and eliminate software that is causing security issues. Penetration testing also allows organizations to strengthen areas of neglect before malicious actors can discover vulnerabilities and launch potent cyberattacks.

There are many secondary purposes for penetration testing as well. Many organizations use penetration testing to see how effective the current incident response strategy is. With so many organizations completing tasks online, security incidents are bound to happen. That’s true even for those organizations that have invested resources in protecting all possible environments. Penetration testing can test whether the current strategy will hold up in a real-world scenario. But penetration testing is not just about protective mechanisms and security tools. Penetration testing is also designed to test how well the security and IT personnel of an organization respond to a security incident.

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Another purpose of penetration testing is to check the security awareness of all important employees in an organization. Some penetration tests only focus on company employees and how employees respond to cyber threats, such as social engineering, phishing and phishing derivatives. Penetration testing can highlight the effectiveness of various training methods and point out employees that may need additional training or reminders. Without penetration testing, organizations simply cannot know which employee is the weakest link.

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Penetration testing is also important for companies to comply with government or industry requirements. Modern standards and regulations, such as PCI and HIPAA, require that companies implement certain safeguards to protect user data from potential attacks. Companies that do not comply with the requirements can face fines and revenue loss and be stripped of certain business privileges. Penetration testing for such organizations becomes critical to know if all the protections are in place, compliance is ensured and security mechanisms work effectively.

A less popular purpose of penetration testing is to develop a clear and comprehensive security policy. Any organization’s security policy can have possible loopholes that attackers may exploit. Even if all the employees of the company follow the rules, if the security policy is not comprehensive enough, hackers can still get through. Another problem that penetration testing is used to solve is the lack of understanding by employees on how to follow a security policy. Penetration testing allows organizations to invest further in cybersecurity training and update current security policies for more protection.

How Is Penetration Testing Done?

Penetration testing is done by doing attacks on the organization’s network to find weak spots. Most of the time, a company hires a cybersecurity professional to perform certain tests to check incidence preparedness. An organization may also have penetration testing done via software applications instead of by professionals. Many cybersecurity tools have automated features that can help organizations recognize problematic areas.


If an organization’s security needs are complex enough, then expert pen testers are a must. Pen testers have the required knowledge and expertise to understand different applications and systems. Such experts can dig deep into networks and computer systems while running security exercises and testing systems with multiple points of attack. Such comprehensive penetration testing is usually done by security teams rather than just one cybersecurity professional.

Whether an organization uses manual or automated methods for penetration testing, all methods and techniques try to systematically attack mobile devices, potential areas of weaknesses, network devices, Wi-Fi networks, applications, other endpoints and servers. After a team of cybersecurity experts or pen testers have identified vulnerabilities and exploited the said vulnerabilities, further cyberattacks may be launched using the compromised devices against other company assets and resources. The primary aim of the pen testing team is to keep gaining higher security clearance levels and access to more sensitive information, along with assets.

Once the testing is finished, cybersecurity professionals aggregate all the information acquired about the security vulnerabilities discovered. Then a report is presented to the network and IT system managers. Managers use that information to make informed decisions about the organization’s security policy and prioritize different activities to mitigate the risks presented by the newly discovered security vulnerabilities.

What Are the Stages of Penetration Testing?

The stages of penetration testing are given below.

  1. Research and Planning
  2. Scanning
  3. Getting Access
  4. Keeping Access
  5. Analysis

1. Research and Planning

The first stage of any penetration testing program is research and planning. In the research and planning phase, cybersecurity professionals first define the scope of the project at hand. Then the goal of the test is decided. During the research and planning stage, cybersecurity professionals study the systems that will be addressed and interacted with, along with the testing methods that will be used for maximum effect. Gathering more information about the problem at hand is another task to be completed during the research and planning phase. Cybersecurity professionals usually need to know all the network names, domain names, the mail server used and any other information that will help understand how the systems and networks of the organization work.

Such information also helps the pen testing team to spot more potential security vulnerabilities.

Other activities such as determining the proper order of test execution, listing the types of tests to be used, informing the concerned personnel within the team and the organization about the tests that will be used and assessing the systems and networks available are also completed during the research and planning phase.

2. Scanning

The second phase of penetration testing is the scanning phase, which is also referred to as the discovery phase. In this phase, the pen testers try to understand all the ways the target device or application would respond to cyberattacks and other intrusion attempts. The two most common ways of proceeding in the scanning stage are doing a static analysis and a dynamic analysis.

In the static analysis, pen testers and cybersecurity professionals observe the code used to build an application. During the inspection, the testers look at all types of behavior the application is likely to show when running under normal conditions. With advanced enough tools, pen testers can go through an application’s code in one go and get the entire picture.

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In the dynamic analysis, pen testers observe the code used to develop an application again. But in dynamic analysis, testers look at the code while the application is running. Some experts feel that scanning an application’s code while running is more effective, since dynamic analysis gives real-time information about the performance of an application during normal operation.

Static analysis is better at truly understanding the nature of the application’s behavior, while dynamic analysis methods are better at giving an accurate representation of how the application actually performs.

3. Getting Access

In the “getting access” phase, pen testers launch the actual attacks.

The “getting access” phase goes by many names, including penetration attempt to exploit weaknesses, attack phase and gaining access. Regardless of the terms used, pen testers use techniques such as backdoors, malicious SQL injection and cross-site scripting to attack web applications. Such methods are aimed at educating the pen testers about a target’s security vulnerabilities. Once a target device has been compromised, pen testers move forward by exploiting the vulnerabilities. More specifically, pen testers steal data, intercept sensitive traffic and escalate privileges. All of such activities allow pen testers to determine the extent of damage in the case of a real cyberattack. The main aim of the “getting access” stage is to infiltrate the organization’s digital environment and demonstrate to clients how deeply the network can be compromised.

4. Keeping Access

The primary aim of the fourth phase of any penetration testing is to maintain a high level of access to compromised systems and networks. Another objective is to see whether an introduced vulnerability can stay persistent in the compromised system for a long period. The longer the period the vulnerability stays in the system, the more chances malicious actors have to cause more damage and gain even a higher level of access to any connected systems and networks. APTs (Advanced Persistent Threats) are especially dangerous for organizations and corporations because of APTs’ ability to remain functional in an exploited system for months while continuing to steal data and transfer the stolen data to a hacker-controlled server.

5. Analysis

In the fifth phase of penetration testing, pen testers prepare reports for the clients. The reports contain further details about the steps taken to exploit any vulnerabilities, the processes used, the successful attempts to compromise a target system and the discovered weaknesses. Any information that will help the organization better prepare for future real attacks is also included in the report. That includes the data pen testers were able to access because of a security vulnerability and the time consumed to infiltrate a system as well as the length of time the pen tester spent in the system after the current security systems detected the security problem.

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After the information is presented to the security professionals, depending on the conclusions, the tests could lead to new WAF (web application firewall) settings along with other security solutions to patch critical vulnerabilities and shore up the organization’s defenses against future cyberattacks.

What Are the Benefits of Penetration Testing?

The benefits of penetration testing are given below.

  1. Regulations and Standards Compliance: For firms looking to generate credibility and gain trust, complying with standards and regulations is important. Penetration testing provides a straightforward way for any company to maintain compliance with all regulations. Depending on the industry, companies have to comply with CMMC, HEOA, NERC, SOX, PCI DSS and HIPAA. Penetration testing allows a company’s infrastructure to get exploited when pen testers demonstrate how a type of cyberattack could allow hackers to steal sensitive data. Most of the regulations mentioned above only require the company to show pen testing results for proper assessment of the organization’s adherence to standards and general security posture. Standards, such as PCI DSS, explicitly require companies to implement comprehensive penetration testing programs.
  2. IT Infrastructure Condition: Penetration testing is mostly about analyzing the organization’s IT infrastructure strength. Pen testers perform an in-depth analysis of a company’s ability to respond to cyberattacks and defend networks with users, systems, applications, endpoints and other company assets. Penetration testing also allows companies to gain a proper understanding of not only external threats but also internal ones. Companies can then begin to manage advanced threats that may cause loss of sensitive data or disruptions to normal processes that depend on data.
  3. Pen Testing Can Detail System Vulnerabilities: Penetration testing processes are designed to root out weaknesses in the entire digital environment that an organization works in. As mentioned in the previous section, pen testers usually hand over a detailed report about all the problematic areas not only in systems but also networks, access points, hardware and software. Penetration testing is a great way for companies to know which areas need improvement and what are the upgrades required.
  4. Penetration Testing Can Correct IT Budgets: Some organizations may have the budget to guard against cyberattacks effectively. But the majority simply suffers from IT spending problems. Penetration testing can pinpoint the areas that need more resources. Pen testers can also highlight areas where the company may be wasting the IT budget. With a detailed pen test report, companies can improve the general security posture and modify, optimize and even amplify the IT budget and allocation of resources.
  5. Pen Tests Can Check for Attack Preparedness: Penetration testing methods are so comprehensive when exposing security vulnerabilities in a system that organizations can easily use the findings to prepare for real-world mitigation and preventive strategies against cyberattacks. Without penetration testing, organizations would find knowing the true extent of threat preparedness difficult.
  6. Penetration Tests Can Help Identity Attack Methods: Without penetration tests, organizations may prepare for cyberattacks that may never happen. Since penetration testing is all about simulating an actual cyberattack as close as possible, the white hat methods used to compromise systems can prepare organizations for specific attacks that are more likely to happen, given the installed networks and systems. Organizations can then improve defenses against specific types of cyberattacks.
  7. Penetration Testing Can Help Organizations Improve Company Reputation and Image: Building and maintaining a reasonable public image and company reputation takes years of work along with high amounts of investment. A single data breach or a hack can undo all that hard work. The scale of damage, in the big scheme of things, does not matter because even if a company can minimize costs and resolve the security issue fairly quickly, losing consumer and investor confidence and trust can hurt the company’s reputation, sometimes permanently. Instead of taking a chance and hoping hackers would ignore a target and risk consequences that could take months and even years to recover from , companies can simply schedule regular penetration tests. Taking mitigation steps and preventive measures while considering the outcomes of a penetration test allows companies to keep hackers and other malicious actors away. Keeping the IT environment clean and secure can then help the company gain more reputation points and potential investor interest.

What Are the Types of Penetration Tests?

The types of penetration tests are given below.

Red Team Penetration TestingPerhaps the most common advanced technique for comprehensive penetration tests is the red team penetration test. The red team penetration test is a military-grade exercise where pen testers take an adversarial approach to attacking organizations’ systems and networks. The primary aim is to put current security plans, processes and policies under a high amount of stress and challenge preconceived assumptions. There is also a blue team component in red team penetration testing whose job is to withstand the red team attacks. The red team Penetration testing technique differs from other techniques as there are two teams that check an organization’s security systems from multiple points of view. Compared to other methods, red team penetration testing is time-consuming and requires a high amount of investment.
Mobile App Penetration TestThe mobile application type of penetration testing covers mobile applications. The techniques used are static and dynamic analysis. Mobile App Penetration testing differs from other methods as servers and mobile APIs are not included in the tests. Pen testers may need information, such as operating system versions and types. Sometimes there might also be a requirement for jailbreaking and rooting the device.
Web Application TestingWeb application testing involves pen testers assessing custom applications with standard websites via the internet. The development and design flaws are uncovered, and the code is checked for vulnerabilities that can be exploited. Web application testing differs from other tests, as pen testers first have to pin down the number of dynamic pages, static pages and apps. Of course, the primary difference is that this type of testing only covers web-based applications.
Network Penetration TestingIn network penetration testing, cybersecurity professionals try to find vulnerabilities in an organization’s network infrastructure, including switches, firewalls and servers. Then avenues to exploit weaknesses are explored. Network penetration testing is different from other testing methods, as this test type protects companies from almost all network-based cyberattacks.
Wireless Penetration TestingAs the name suggests, wireless penetration testing is used to find faults in services that enable data transfer via networks. Wireless penetration testing is different from other tests, as the main areas to protect and enhance include data exfiltration and unauthorized access. Wireless penetration test also identifies router misconfiguration, deauthentication attacks and session reuse.
Social Engineering TestingSocial engineering testing is another type of penetration testing where the main activity is to test the organization’s vulnerability to confidential information leakage via the staff. Social engineering differs from other types, as the primary target for the test are employees rather than hardware or digital systems.
Physical Penetration TestingIn physical penetration testing, pen testers simulate physical attacks that may breach a company’s security controls. Physical penetration testing differs from other types as the aim is to look at physical security vulnerabilities such as USB-based attacks, real-life premises intrusion and theft.
IoT Penetration TestingIoT penetration testing is all about discovering security vulnerabilities in embedded software, hardware, communication protocols, mobile applications, servers and any other ecosystem that connects to IoT devices. IoT penetration testing is vastly different from other pen tests, as this test has to be specific to the device under study and may require relatively novel techniques such as signal capture analysis, firmware analysis and data dumping.
Client-side Penetration TestingClient-side penetration testing is focused on security vulnerabilities present on applications on client computers. Such applications include media players, web browsers, software packages for content creation and image editing tools. Client-side penetration testing differs from others as the tests are designed to check for attacks such as malware infection, open redirection, HTML injection, cross-site scripting and cross-origin resource sharing.

Who Conducts Penetration Tests?

Usually, penetration testing experts conduct penetration tests. The best person to conduct a penetration test for an organization is someone with the right qualifications and no knowledge of the company’s security systems. That’s to ensure that the pen tester does not miss the vulnerabilities the developers of the system or network missed.

The person who conducts penetration tests is also known as an ethical hacker. Ethical hackers can be hired from third-party cybersecurity companies or as in-house employees. Whatever the case may be, the qualifications required for ethical hackers are mostly the same for any cybersecurity professional. Ethical hackers have to be IT experts who possess knowledge about methods that can help organizations to identify security vulnerabilities present in apps, web-based interfaces, endpoints, networks, hardware, software and the general IT infrastructure. Ethical hackers are also required to have extensive knowledge of how wired and wireless networks and connections work. The most important certifications are OSCP (Offensive Security Certified Professional) and CEH (Certified Ethical Hacker). Other helpful skills that a penetration tester must possess for carrying out effective penetration tests include knowledge of various operating systems, firewalls, file systems, permissions, general coding principles, analytical thinking and presentation skills.

When Should Penetration Testing Be Performed?

Different organizations and cybersecurity professionals give different answers to how often penetration testing should be performed. Penetration tests should be performed at least once every 12 months. The more regular penetration tests are performed, the better. Of course, a company has to look into the resources that can be put into hiring pen testers and launching penetration tests.

Depending on the industry, a company may have to hire professionals to perform penetration tests more than once a year. For example, regulations such as GDPR, HIPAA and PCI DSS also require concerned companies to carry out penetration tests whenever end-user policies are modified or new security patches are applied. Depending on the jurisdiction and the nature of business, a company may have to perform penetration tests every time there is a change of location of the office, upgrades are applied to applications or IT infrastructure or new applications or network infrastructure are added.


Apart from scheduled penetration tests, there are also specific times when performing a penetration test can help an organization stay safe from new forms of cyberattacks. For example, if the organization is going through a crucial development phase of a product, then that’s probably not the best time to perform a penetration test. In large projects, testing as the core features of an application become ready can be beneficial, though.

Another example is when an organization already knows the most important security flaws. Vulnerabilities that are already known should be fixed first. There is no point in investing in a penetration test team only to find vulnerabilities that are already known. The risk of unidentified vulnerabilities will still be there. And that’s why organizations should first fix known vulnerabilities and then get a cybersecurity team to perform a penetration test as soon as possible afterward.

If the organization hasn’t progressed in the reports of the previous penetration test, then performing another penetration test is a waste of time and sources. Such organizations should first put the company on the correct security path, go through the previous security audit, implement the fixes and then perform another penetration test. Another benefit of using such an approach is that penetrated testers would also be able to check whether the newly implemented security policies are working because of the previous penetration test.

What Are the Best Penetration Testing Tools?

Since there is no single best penetration testing tool, different security tools can become more useful than others in different situations. A penetration testing team should be able to manage all the best penetration testing tools to perform a comprehensive penetration test. The list of best penetration testing tools is given below.

  1. Kali Linux (Best Overall): A list containing the best penetration testing tools is unlike any list of best security tools. That’s because each tool is different and performs a certain critical task. But if penetration testers had to choose one tool out of all the best penetration testing tools, then Kali Linux would be the best tool. That’s because Kali Linux provides the most stable pen testing operating system. The operating system comes with all the best penetration testing tools that penetration testers require.
  2. Nmap (Best for Gathering Information): Nmap is more than just a simple port scanner. The tool can discover which ports are open and what kind of activities are running on the open ports. Nmap is legal and used by hundreds of companies to map the security posture of public and private companies.
  3. Wireshark (Best for Discovering Traffic Statistics): Wireshark is the best network protocol analyzer. Any penetration tester who wants to know more about an organization’s network traffic must get hold of the Wireshark application. Wireshark offers features such as decryption support, real-time protocols analysis and tools for everyday TCP/IP connection issues.
For more information on what are the best security penetration testing tools, refer to this guide.

Is Penetration Testing Necessary?

Yes, penetration testing has become necessary in the modern world where companies, regardless of industry, generate data, have to store that data and usually are connected to the web in some form. Since the cost of data breaches to companies has also gone up since the pandemic, penetration testing has become even more necessary. Penetration tests are necessary for all companies and organizations that have an interest in preparing for future attacks. Without penetration testing, organizations cannot realistically train personnel on all the dos and don’ts of a malicious cyberattack. Penetration testing has become necessary because organizations need to know if current security policies are comprehensive enough to be effective against modern cyberattacks. Penetration testing is also necessary for any organization that needs to identify risks accurately. Pen testers are experts at offering insights on applications and network areas that are most at risk. Pen testers can then recommend tools and security policy changes that need more investment and expertise to further guard against newer cyberattacks.

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Penetration testing also becomes necessary for organizations where there is a need to decrease errors by developers and report generators. Developers are experts at developing apps, not at anticipating which weak spots malicious actors are likely to exploit in a cyberattack. Penetration testing can fill that hole and educate developers on exactly how a malicious actor would exploit an application or software or even the operating system. Because of comprehensive penetration testing reports, organizations can become more dedicated to learning all the ways to stop malicious actors that prey on mistakes and common errors.

Damien Mather Damien is a cybersecurity professional and online privacy advocate with a bachelor of Computer Science. He has been in the industry for 20+ years and has seen the space evolve far bigger than he ever thought. When he is not buried in his research or going through code, he is probably out Surfing or Camping and enjoying the great outdoors.