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What Is Penetration Testing?

Dec 2, 2021

When people think of a hacker, they may picture a villainous figure breaching a security system. However, many “hackers” are everyday IT professionals performing a valuable service for organizations across the globe. 

 Penetration testers are often referred to as “ethical hackers.” They work to uncover security vulnerabilities in computer systems and help organizations protect their data from cybercriminals. To those unfamiliar with ethical hacking, a penetration test can be a foreign concept. Read on to learn more about penetration testing and why it's critical to cybersecurity. 

What is Penetration Testing?

Also known as a “pen test” or “white-hat hacking,” a penetration test is a simulated cyberattack against a computer system to find exploitable security vulnerabilities. "Black hat” hackers breach computer systems illegally, while “white hat” hackers work to improve security systems t penetration tests, vulnerability scanning, and other services. Penetration testing helps organizations mitigate security risks, protect sensitive data, and optimize incident response plans. Penetration testing is also essential for maintaining compliance in highly regulated industries such as banking and healthcare. 

Pen testing helps businesses answer the question, “Is our data easy to steal?” Data breaches are costly. IBM estimates that U.S. companies lose an average of $4.45 million per data breach! Data breaches and other security incidents also erode a company’s reputation and cause customers to lose trust in the organization. 

What are the Five Stages of Penetration Testing?

Protecting against data breaches through pen testing requires a systematic approach. Penetration tests typically involve the following stages: 

  1. Planning and reconnaissance. The pen tester works with the cybersecurity team to identify the test objectives and scope. Next, the pen tester conducts preliminary system reconnaissance by gathering information about the network layout, operating systems, and applications. 
  2. Vulnerability assessment. The tester analyzes the network and computer system to uncover access points and potential weaknesses. The tester searches for easily guessable passwords, programming mistakes, inadequate data protection, and other flaws that could increase the chances of a cyberattack. They often use automated tools such as vulnerability scanners to expedite this process. A vulnerability scanner evaluates computer networks, systems, and applications for weaknesses that could pose a security risk. Some of the most popular vulnerability scanners include Nessus, Trivy, SonarQube, and Acunetix. 
  3. Security breaching. The tester uses cross-site scripting, SQL injection, backdoors, and other strategies to pinpoint where they can bypass the firewall and break into the system. The penetration tester acts as a real cybercriminal would act. They attempt to extract exploitable information, weaken the organization’s security system, and maintain access for as long as possible. The tester evaluates the risk of privilege escalation, which occurs when security flaws allow a bad actor to access resources or capabilities above and beyond what they should have access to. 
  4. Documentation. At the end of the test, the penetration tester compiles a comprehensive report containing a description of the exploitable vulnerabilities and their potential impact, an evaluation of the organization’s incident response procedures, and strategies for improving the organization’s security systems. 
  5. Remediation. An important part of a penetration tester’s job is helping organizations mitigate security risks and protect against cyberattacks. They propose mitigation strategies such as installing security patches, using multi-factor authentication, encrypting data, or limiting user permissions. The pen tester may conduct additional tests after the mitigation steps are completed to ensure that the security vulnerabilities have been adequately addressed. 

What are Three Types of Penetration Testing?

Penetration tests can be generally categorized as black-box, gray-box, or white-box assessments. Let’s take a deeper look at each one. 

 Black-Box Test 

In a black-box test, the tester is given no information about the internal workings or architecture of the target system. They’re asked to hack into the system armed with only an outsider’s knowledge. The penetration tester is put in the shoes of an average hacker. The main goal of a black-box assessment is to find any easily exploitable vulnerabilities. This is often the most authentic type of penetration testing because many cybercriminals attack from outside of an organization.

Gray-Box Test 

A gray-box assessment simulates an attack from a hacker with minimal knowledge of the internal security system. The tester is provided basic information regarding the system's intricacies, architecture, and design. Gray-box testers play the part of someone who already has access and privileges within a system. A gray-box test can often provide a more efficient and targeted security assessment than a black-box test. 

White-Box Test 

White-box testing, or clear-box testing, is the opposite of black-box testing. The penetration tester is given total access to credentials, source code, and the system architecture. It’s a very time-intensive, thorough form of penetration testing that reveals external and internal vulnerabilities. White-box penetration testers have the same level of knowledge as a developer. Working together, developers and white-box pen testers can ensure that a system is secure.  

What are the Categories of Penetration Testing?

The penetration test approach depends on the organization’s needs, industry regulations, and specific test objectives. 

External Testing 

An external penetration test targets company assets that are visible to external parties such as websites, web applications, domain name servers (DNS), and emails. The goal of these tests is to see if hackers can gain access to and extract data from external systems. This type of penetration testing measures a system’s vulnerability to outside attackers. 

Internal Testing 

An internal penetration test simulates an attack by a malicious insider—someone with access to systems behind a company’s firewall. This pen testing method can also assess employees’ suseptibility to external social engineering attacks. 

Blind Testing 

In a blind test, a pen-tester acts as a real hacker and uses publicly accessible information to access a system. While the tester is “blind,” the organization knows how, when, and what a penetration tester will attack. A blind test provides a good level of vulnerability assessment, though it is not quite as informative as a double-blind test. 

Double-Blind Testing 

In a double-blind test, which is also called a “zero-knowledge test,” the pen tester and target are unaware of the test’s scope. Security personnel have no advance knowledge of the simulated attack. Double-blind testing is like a school fire drill where neither students nor teachers know about the drill. This provides a more realistic picture of an organization’s security vulnerabilities and incident response capabilities. 

Targeted Testing 

The tester and the organization’s security team work together to evaluate security systems during targeted testing. This gives the cybersecurity team invaluable real-time feedback from a hacker’s point of view. Targeted tests are often focused on specific, high-priority applications or networks. 

Examples of Penetration Testing

Penetration testers use a variety of techniques to simulate real-world cyberattacks and discover security vulnerabilities, including:

  • Social engineering simulations. Cybercriminals often use social engineering tactics such as phishing emails to coerce an organization’s employees into revealing sensitive data. Phishing hackers often disguise themselves as internal employees asking for specific information or “confirming” a user’s log-in credentials. A penetration tester may scrutinize an organization’s vulnerability to social engineering by sending a simulated phishing email and noting whether employees recognize it as a scam. 
  • Ransomware attack simulations. In a ransomware attack, users are prompted to download files, often disguised as antivirus software, that infect a computer or network and lock system administrators out until they pay a ransom. A penetration tester may simulate a ransomware attack to determine whether employees will respond appropriately to illegitimate download requests. 
  • Network penetration tests. The penetration tester acts as a cybercriminal attempting to breach the organization’s network. They try to exploit firewalls, routers, switches, and servers to access sensitive data. The tester may also determine whether it's possible to intercept data shared over wireless networks. 
  • Web application tests. The penetration tester identifies vulnerabilities in a web application that cybercriminals could exploit. They may upload files with malicious content, intentionally trigger application errors, or use brute force tactics to infiltrate password-protected files. 
  • Physical penetration tests. Penetration testers may also evaluate the strength of physical security measures such as digital locks, alarms, and access controls. For example, the tester may check whether an RFID cloner or similar device could be used to duplicate employee badges and access secure areas of an organization. 

Penetration testing is an intricate and highly specialized discipline. It’s also a practice that’s critical to an organization’s security. We live in a digital world where more and more data is stored online and the number of cybercriminals and cyberattacks is rising. This means that in coming years, the demand for penetration tests and other types of security testing will only continue to grow.  

The Role of Ethics in Penetration Testing 

Penetration testers are given significant access to secure areas of an organization's network. An unethical pen tester can use their skills and resources to exploit vulnerabilities in a system, sell sensitive data, or sabotage the organization. Penetration testing involves substantial legal and ethical boundaries to keep organizations, clients, and customers safe.

Client Trust  

Security system optimization through penetration testing requires a great deal of trust. The company hiring the penetration tester trusts that the tester will adhere to legal and moral standards, maintain confidentiality, and confine their testing activities within the specified parameters. Investors and other stakeholders trust that the company hiring the penetration tester has completed its due diligence and appointed a qualified tester.

Penetration testers earn and maintain a client’s trust by maintaining a clear, open line of communication, adhering to the test objectives and scope, maintaining confidentiality, and upholding a high standard of professionalism. 

 Legal Boundaries

What’s the difference between an ethical hacker and an unethical hacker? It all comes down to consent. Clients give penetration testers explicit authorization to conduct penetration tests, whereas unscrupulous hackers conduct hacks without permission. Before penetration testing begins, the involved parties negotiate and sign a contract that specifies the assignment’s scope and timeframe, gives the tester written permission to perform penetration tests, and binds the parties to confidentiality. Penetration testers who access unauthorized information, disclose confidential data, or otherwise breach the written contract can face significant civil and even criminal consequences, including jail time.  

 Data Integrity

Penetration testers have an ethical responsibility to maintain the integrity of the data contained within the target system. Irresponsible penetration testing can damage or destroy data. Penetration testers must avoid interacting with data outside the specified parameters. Skillfully planned penetration tests use the least intrusive methods possible to assess a system and identify vulnerabilities. They avoid changing or deleting any data. However, unintended consequences can still occur, so penetration testers create backups of crucial data before testing begins. If data is lost or corrupted, the tester can restore the data using the backups. 


Penetration testers identify security risks and vulnerabilities to help organizations protect themselves against cyberattacks. A test is only helpful to a client if the tester shares their findings and the significance of their discoveries to the client. Pen testers create a report detailing each security risk, its potential impact, and proposed remediation steps. After the client implements additional security measures and makes the necessary changes, the pen tester may conduct further tests to ensure that the risks have been adequately addressed.   

 Professional Standards 

Because they’re given extensive access to sensitive data and systems, pen testers are held to high standards in terms of professionalism, trustworthiness, and competence. Most penetration testing jobs require at least bachelor’s degree in IT, cybersecurity, or a related field. Additionally, many employers and clients prefer penetration testers who have earned a professional certification that confirms their knowledge of penetration testing methodologies, ethical standards, and regulatory and compliance matters. 

Some of the top certifications for penetration testers include: 

  • CompTIA PenTest+
  • Certified Ethical Hacker (CEH)
  • Certified Penetration Tester (CPT)
  • Certified Expert Penetration Tester (CEPT)
  • Certified Cloud Penetration Tester (CCPT)
  • Certified Mobile and Web Application Penetration Tester (CMWAPT)
  • Certified Red Team Operations Professional (CRTOP)
  • EC-Council Licensed Penetration Tester (LPT) Master
  • Global Information Assurance Certification (GIAC) Penetration Tester (GPEN)
  • Offensive Security Certified Professional (OSCP)
  • CompTIA Cybersecurity Analyst (CySA+)
  • CompTIA Advanced Security Practitioner (CASP+) Optional Voucher
  • ISACA Certified Information Security Manager (CISM) Optional Voucher
  • (ISC)² Certified in Cybersecurity (CC)

 Next Steps 

Are you interested in the exciting world of ethical hacking? WGU’s affordable online degree programs can empower you with the skills and knowledge needed to thrive in a penetration testing career. WGU’s College of Information Technology offers a B.S. in Cybersecurity and Information Assurance, a B.S. in Network Operations and Security, a B.S. in Computer Science, and several other career-aligned IT bachelor’s degree programs. You can earn your degree on your own schedule, studying when and where it’s convenient for you. Take your career prospects to the next level by earning a bachelor’s or master’s degree at WGU. Apply today!

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