What Is Penetration Testing?

What Is Penetration Testing? Strategic Approaches and Types

February 1, 2022
| Penetration Testing

In response to the global COVID-19 pandemic, organizations are facing the challenge of optimizing their security infrastructures. Due to the widespread shift to remote work, more business data than ever travels through cloud services (Sumina, 2021), and employees are using personal devices and home Wi-Fi networks for business more frequently (Kiernan, 2021).

As the need for improved endpoint security has increased, demand has skyrocketed for cybersecurity professionals who can test systems and diagnose security vulnerabilities. Penetration testing, in particular, has come to play a key role in organizations’ security procedures, and there is a growing need for more qualified penetration testers (EC-Council, 2021). Cybersecurity professionals with penetration testing certifications monitor and audit security parameters by conducting various tests using both automated and manual tools.

What Is Penetration Testing?

Penetration testing is a technique used in cybersecurity to identify vulnerabilities in applications or networks. Penetration testers are also often responsible for assessing an organization’s security policies, compliance, and employee awareness of security protocols. Clients can use the findings from a penetration test to fix vulnerabilities before a security breach occurs. Many organizations also conduct penetration tests of new products before release.

Why Conduct a Penetration Test?

Organizations need to keep their sensitive data safe from cyberattacks. Penetration testers are trained to assess the vulnerability of an organization’s systems and networks by examining them for design flaws, technical vulnerabilities, and more. After performing these assessments, penetration testers can recommend actions the organization can take to rectify any issues discovered during the tests.

Is Penetration Testing Useful for Small Businesses?

Penetration testing is highly useful for small businesses, as startups and small businesses are the primary targets of cybercriminals. In some industries, penetration testing is compulsory for businesses. Penetration testing can even help small and medium-sized enterprises grow by improving their resiliency.

Penetration Testing Phases

A penetration test typically involves the following phases. Since different types of penetration tests have distinct purposes and scopes, a specific penetration test may focus more heavily on some of these phases or omit others.

1. Pre-engagement

In the pre-engagement penetration testing phase, the tester and client define the scope of the penetration test, such as what systems will be tested, what methods the tester will use, and any additional goals and legal implications.

2. Reconnaissance

Reconnaissance requires the tester to collect as much information on the testing subject as possible, including personnel, technology, and systems information.

3. Threat Modeling

After collecting sufficient information on the client’s system, testers then begin modeling realistic threats that the client will face before scanning for the relevant vulnerabilities in the system that those attacks would normally target.

4. Exploitation

All identified vulnerabilities are exploited at this stage in accordance with the scope outlined in the pre-engagement phase.

5. Post-exploitation

Once the testing time has run out or all relevant systems have been exploited, all testing methods and vulnerabilities—including associated devices, ports, or personnel—are recorded.

6. Reporting

The tester generates a penetration testing report for the client that describes the methods that were used, what vulnerabilities were exploited, what remedial actions should be undertaken, and any other relevant information.

7. Re-testing

After the client has had time to resolve the vulnerability issues outlined in the initial report, the tester can return to run the same penetration tests on the client’s system to verify that the vulnerabilities have been resolved. This phase is not as common but may be requested by the client.

Strategic Approaches to Penetration Testing

There are three main strategic approaches to penetration testing, each of which involves different steps and tools. The key differences in these approaches involve the extent of the theoretical attacker’s knowledge of the target system or network.

1. Gray-Box Penetration Testing

In a gray-box penetration test, the penetration tester has basic knowledge of the target system, such as initial access credentials, a network infrastructure map, or application logic flowcharts. Gray-box penetration tests therefore create a realistic attack scenario, since malicious hackers don’t normally attack without first collecting information about their target.

2. Closed-Box Penetration Testing

In contrast, in a closed-box penetration test (also known as a black-box penetration test), the penetration tester has no prior knowledge of the target network or system. Since the tester has no access to information such as internal code, software, credentials, or sensitive data, closed-box penetration tests force testers to think like a potential hacker when searching for vulnerabilities. Unlike an actual malicious hacker, however, a closed-box penetration tester only has limited time in which to access and test the system.

3. Open-Box Penetration Testing

Open-box penetration tests (also known as white-box penetration tests) are less like a cyberattack and more like a complete scan of a system at the source code level. In an open-box penetration test, the tester has the highest possible level of access to the target system. The goal is to allow the tester to break through the system’s security measures so that they can locate logic vulnerabilities, misconfigurations, poorly written code, and inadequate security measures. While open-box penetration tests are comprehensive, they still may fail to identify vulnerabilities that an attacker would exploit. Therefore, it’s generally best to combine open-box testing with closed-box or gray-box testing.

Types of Penetration Testing

There are five main types of penetration test, each of which focuses on different security vulnerabilities and uses a unique set of tools. Understanding the different forms of penetration testing is essential in ensuring that you can find the appropriate test to suit your needs.

1. Network Penetration Test

In a network penetration test, the penetration tester audits a network environment for security vulnerabilities. Network penetration tests can be further subdivided into two categories: external tests and internal tests. An external penetration test involves testing public IP addresses, whereas an internal test provides the tester with network access so that they can emulate a hacker who has already penetrated the network’s defenses.

Penetration testers focus on the following areas in network penetration tests:

  • Firewall configuration
  • Firewall bypass testing
  • Stateful inspection analysis
  • Intrusion prevention system deception
  • DNS-level attacks

2. Web Application Penetration Test

In a web application penetration test, testers search for security problems associated with the insecure design, development, or coding of a web app. These types of tests focus on browsers, websites, web applications, and related items, including plug-ins, procedures, and applets.

3. Client-Side Penetration Test

Client-side penetration tests identify security vulnerabilities within an organization. These are often located in the programs and applications the organization uses, such as email platforms, web browsers, and Adobe Acrobat.

Hackers may, for example, gain access to a vulnerable application through a well-crafted email directing an employee to a malicious webpage or load malware onto a USB stick that can execute the malware once it is inserted into a device. Client-side penetration tests aim to identify these risks and address all related internal vulnerabilities.

4. Wireless Network Penetration Test

Wireless network penetration tests focus on vulnerabilities in wireless devices, such as tablets, laptops, notebooks, and smartphones. These tests aim to identify all devices used by an organization that are vulnerable to cyberattacks. These vulnerabilities may include wireless devices’ security controls, access point configurations, or weak security protocols.

5. Social Engineering Penetration Test

Social engineering penetration tests focus on the human aspect of an organization’s security. In a social engineering test, testers attempt to deceive employees into giving up sensitive information or allowing the tester access to the organization’s systems. This enables penetration testers to understand the organization’s vulnerability to scams or other social engineering cyberattacks.

Testers often use phishing scams as part of social engineering tests. Physical testing may be another aspect of a social engineering test: Penetration testers can attempt to gain access to a secured building or location for which they don’t have clearance by taking advantage of employees’ ignorance of security protocols.

How Can You Become a Penetration Tester?

Penetration testers use many approaches and tools to locate vulnerabilities in organizations. One of the best ways to gain a comprehensive understanding of penetration testing strategies and techniques is to earn your penetration testing certification through EC-Council’s Certified Penetration Testing Professional (C|PENT) course.

To obtain the C|PENT, you can choose between two certification pathways. The first option is to join the C|PENT Training Course, where you’ll receive extensive instruction on penetration testing methodologies. The other option is the C|PENT Challenge, a demanding test designed for those who already have advanced knowledge of penetration testing. Applicants who pass the C|PENT Challenge will have their course fees waived, enabling experienced penetration testers to earn a highly respected credential in their field. Start your certification journey with EC-Council today!


EC-Council. (2021, October 25). What is penetration testing? https://www.eccouncil.org/what-is-penetration-testing/

Kiernan, D. (2021, February 11). BYOD trends to watch in 2021. Cass Information Systems. https://www.cassinfo.com/telecom-expense-management-blog/the-future-of-byod-6-key-trends-for-2020

Sumina, V. (2021, November 21). 26 cloud computing statistics, facts & trends for 2022. Cloudwards. https://www.cloudwards.net/cloud-computing-statistics

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