What is penetration testing?

Learn what penetration testing is, how it’s done—from planning to reporting—and why it protects your business. Secure systems before attackers do.

In today’s digital age, cyberattacks are becoming more prevalent, with hackers discovering new ways to attack using the most secure systems.

This rise of cyberattacks popularized the concept of penetration testing: an active security technique in which an honest security professional attempts to break into your systems before an attacker does.

Penetration testing is a process in which cybersecurity professionals reproduce real-world attacks on systems to identify vulnerabilities. These systems could be computer systems, networks, and web applications.

Penetration testers perform the process under a user’s consent in a controlled environment. This technique has grown in importance as organizations meet more security risks, with regular testing helping identify and correct vulnerabilities before hackers use them.

“Penetration testing is not just about finding vulnerabilities—it’s about understanding how those vulnerabilities could impact your business in the real world,” says Chris Nickerson, a Red Team Security expert and founder of LARES Consulting.

While standard security testing searches for known flaws, penetration testing goes beyond that by actively attempting to exploit these flaws.

Why do companies conduct penetration testing?

“Security is a process, not a product.” – Bruce Schneier (Information Security Specialist)

Penetration testing is often a standard compliance requirement from organizations and enterprises.

This is because real-world attacks on systems can be costly and devastating, so organizations perform penetration testing to ensure they can safeguard their customers from such attacks. More specifically, companies conduct penetration testing to:

1. Prevent financial crisis

The Equifax data breach exposed data of around 147 million users. An unpatched vulnerability caused the data breach, which could have been easily spotted via penetration testing.

2. Ensure customer trust

When a security breach happens, customers feel their data may be compromised, which erodes their trust in the company, affecting your organization’s reputation and brand.

3. Secure complex systems

Modern software utilizes a complex architecture that depends on internal and external APIs, clouds, mobile, etc. This expands the scope of vulnerabilities that can be exploited.

4. Validate security investments

Penetration testing offers a means to safely check and validate if an organization’s existing security tools—like monitoring systems, firewalls, etc.—are working as they should.

The penetration testing process

Penetration testing is the final step in the security testing process. It’s performed after basic security scans and risk evaluations. Standard security testing searches for known flaws.

Penetration testing goes beyond that by actively attempting to exploit these flaws. The process of penetration testing is meant to find all the potential points of risk in your system before a bad actor exploits them.

Who does it?

Penetration testing is frequently carried out by qualified security professionals. These professionals are also known as “ethical hackers.”

They combine extensive technical knowledge with innovative problem-solving abilities. They can be internal security teams or external consultants, each providing their perspective to identify dangers you may have missed.

What are its goals?

The main goals of penetration testing include:

1. Identifying security weaknesses: Find vulnerabilities in your systems before real attackers do, allowing you time to address them.
2. Testing your defense systems: Check that your security measures perform as expected in real-world attack scenarios.
3. Meeting compliance requirements: Help your firm comply with security requirements and regulations by demonstrating effective security measures.
4. Improving incident response: Test your team’s ability to recognize and respond to security breaches, which will help them prepare for real-world attacks.

A vulnerability scanner may detect that some software is outdated, but penetration testing goes further to detect or exploit a vulnerability like SQL injection that can be detrimental and cause more damage.

Penetration testing vs. vulnerability assessment vs. vulnerability scanning

Penetration testing is often confused with vulnerability assessment and vulnerability scanning. However, these are all different terms.

Vulnerability scanning is an automated process that is used to detect known issues of low risk. Vulnerability assessment can be a semi-automated or a manual process to prioritize risks and detect medium-risk issues.

Penetration testing, on the other hand, is a fully manual process to exploit high-risk vulnerabilities.

For instance, a vulnerability scanner may detect that some software is outdated, but penetration testing goes further to detect or exploit a vulnerability like SQL injection that can be detrimental and cause more damage.

Types of penetration testing

“The key to good security testing is knowing that different attack surfaces require diverse testing methods. One size does not fit all in penetration testing,” says Dr. Charlie Miller, a former National Security Agency hacker and well-known security expert.

1. Network penetration testing

Network penetration testing involves a security specialist investigating all possible weak spots or entry points of your office network.

Whether it is an old wireless network that is not secure, a firewall that has a blind spot, or others, network penetration testing makes sure your system is protected against potential attacks.

2. Web application testing

This is similar to assessing the security of your online business or bank website.

In web application testing, testers attempt to get into your website using techniques such as logging in as another user, stealing client information, or manipulating prices in your online store.

For example, they may attempt to adjust the price of a product in your shopping cart from $100 to $1 or view other customers’ orders. That helps in identifying weak points before actual attackers can exploit them to steal data or money.

3. Mobile application testing

This focuses on testing apps for phones and tablets. In mobile application testing, testers determine if your mobile app manages user data safely, such as passwords and credit cards. 

For example, they check to see if the app accidentally saves passwords in plain text, where anyone can see them, or if data is stolen when a user makes a purchase. They also ensure that the app is secure even when linked to public WiFi in coffee shops.

Social engineering testing checks for human security by tricking staff into making security errors.

4. Social engineering testing

Social engineering testing checks for human security by tricking staff into making security errors.

Testers may send bogus emails claiming to be the CEO and requesting passwords, call pretending to be IT assistance or attempt to enter the office by following an employee through the door.

For example, they could send a bogus urgent email to employees requesting that they log into a duplicate of your company’s website to obtain their passwords. This helps identify which staff members require more security training.

5. Physical penetration testing

Physical penetration testing includes assessing your actual building security. Testers attempt to enter restricted places such as server rooms or offices. They could try to sneak in by following personnel, picking locks, or pretending to be delivery people.

For example, they could leave a USB drive in the parking lot and observe whether employees plug it into corporate computers, or they could try to gain access to the server room by acting as maintenance staff.

This aids in detecting vulnerabilities in your physical protection before real thieves can exploit them.

Types of penetration testing services

Organizations can also choose types of penetration testing services based on their infrastructure and risk exposure.

1. External testing

In external testing, the tester simulates an attack with no internal access. They target internet-facing assets such as APIs, websites, servers, etc.

They attempt to breach the system from outside the network, much like how a real hacker scans for any exposed vulnerabilities on the public internet would.

2. Internal testing

Internal testing is when a tester assumes the attacker already has some level of access, like compromised employee credentials or an insider threat.

The goal is to find out how far an attacker can move within the network, if they can escalate privileges, or if they can access any sensitive data from inside the system.

3. Red teaming

This testing service involves a stealthy attack simulation that tests not just the technology but also the people and processes.

It combines technical exploits, social engineering, phishing attacks, physical intrusion, and so on to mimic real-world adversaries over an extended period of time.

4. Cloud testing

This testing is focused on identifying any misconfigurations or vulnerabilities in cloud environments like AWS/Microsoft Azure. It includes issues like exposed storage buckets, weak IAM roles, insecure APIs, improper network configurations, etc.

5. API testing

This targets any backend services or endpoints that connect with the application.

Testers typically use these APIs to analyze authentication mechanisms, input validation, rate limiting, and data exposure to ensure that these APIs don’t leak any sensitive data or allow any unauthorized access.

Penetration testing methodologies

Penetration testing typically follows a structured and methodical approach. If the level of access to the system is limited, black box testing may be performed to simulate external attacks.

If partial access is available, gray box testing may be utilized. And if complete system knowledge is available, white box testing can be used to perform deep internal testing.

Common frameworks such as the OWASP Testing Guide (commonly used for detecting SQL injection and XSS attacks) or PTES (which defines the full life cycle of a penetration test) can be used.

How does penetration testing work?

“A thorough penetration test should mirror real-world attack scenarios as closely as possible,” emphasizes Dave Kennedy, founder of TrustedSec and creator of the Social-Engineer Toolkit.

The penetration testing process follows a structured approach. This helps to ensure nothing is missed during the security assessment:

Planning and monitoring

Testers begin by gathering all available information about your systems, much like a detective researching a case. They examine your network topology, identify the systems you’re using, and decide which regions require testing.

This step also includes establishing specific goals, timetables, and engagement rules. These rules define what testers can and cannot do throughout their evaluation. They may even look at your company’s public information and social media to identify potential weaknesses.

After the planning is completed, testers use specialized tools to examine your systems for potential vulnerabilities.

Examining the system

After the planning is completed, testers use specialized tools to examine your systems for potential vulnerabilities. Imagine a doctor utilizing an X-ray machine to look for issues.

They investigate how your network responds to various types of connection attempts, determine which services are running on your systems, and uncover any security flaws.

This phase includes static analysis (evaluating systems while they are not running) with dynamic analysis (testing systems while they are running).

Gaining access

Now comes the actual “testing” phase. Using the information acquired, testers attempt to exploit the vulnerabilities they have identified. They might try password cracking, exploiting software flaws, or deceiving security systems.

Simulating persistent threats

After getting access, testers attempt to stay inside your systems for a long period. This helps them understand whether your security staff can discover unwanted access and how long it will take.

They may attempt to install hidden software or set up secret user accounts. This phase shows how much damage a real attacker could do if they got into your systems and were not detected quickly.

Analysis and reporting

Finally, testers compile everything they’ve found into detailed reports. These reports include vulnerabilities they discovered, how they managed to exploit them, what sensitive data or systems they accessed, and clear step-by-step recommendations for fixing each problem.

What are the main steps of penetration testing?

A penetration test follows a structured approach that attackers often take.

Reconnaissance or information gathering

This is the discovery phase, where testers try to collect as much information as they can about the system and the target. Any publicly available data and internal system context like domains, subdomains, tech stack, employee roles, exposed endpoints, etc.

A tester analyzing an e-commerce site might look into subdomains such as admin.shop.com or api.shop.com and identify the underlying tech stack used, such as ReactJS for frontend, Python Flask for backend, etc.

They might try to find employee emails via LinkedIn that could be used in simulating phishing attacks.

This information gathering helps the testers map the attack surface before any testing begins.

Scanning and enumeration

In this step, testers actively engage with the system and probe it to identify entry points. They do this by scanning for open ports, running services, APIs, known vulnerabilities, etc.

For example, let’s say a scan reveals that port 443 with HTTPS 8085 for the admin panel is left open. The admin panel is accessible without any IP restrictions and the API endpoint /api/v1/users exposes too much data.

At this stage, testers are essentially finding any doors and windows that get them access to the system.

Exploitation

In this step, the testers try to exploit any vulnerabilities they’ve identified to gain access to the system. Here, they simulate real attacks like SQL injection, bypassing authentication, misconfiguring or manipulating any access controls, etc.

For instance, the tester could input ‘1’ = 1 in the login field, and if the system hasn’t sanitized the input, a login bypass could be achieved. This will expose the vulnerability of gaining unauthorized access to a user’s account.

Exploitation reveals that a vulnerability is not just theoretical, but actually exploitable.

Privilege escalation

Once the tester has gained access to an account, their next step is getting to a higher-level access account (e.g., going from user to admin).

Here, testers are trying to look for weak permissions, any tokens that are exposed, misconfigured roles, etc.

For instance, if the tester discovers that changing a user ID in a request could simply expose the admin data, they could exploit this to gain admin privileges, which could lead to an attacker completely compromising the system.

Post-exploitation

In this phase, testers try to evaluate how far an attacker can go after they gain access to the system. They simulate persistence, lateral movements, and data extraction.

This step gives an overview of the worst-case scenarios and the type of damage that scenario could cause. For example, accessing a customer database, downloading any personal emails of the user or payment-related metadata, creating hidden admin accounts to maintain access, etc.

A good report doesn’t just highlight the problem, but it also gives actionable steps organizations can take to fix those problems efficiently.

Reporting

In this last step, testers document and collate all their findings and also provide clear, actionable insights. They lay down the vulnerabilities they’ve discovered, steps to reproduce those vulnerabilities, their business impact, recommendations for remediation, etc.

A good report doesn’t just highlight the problem, but it also gives actionable steps organizations can take to fix those problems efficiently.

How is a typical pen test carried out?

Let’s walk through a realistic penetration test of an e-commerce web application to understand what the tester is actually doing and how they’re performing these steps under the hood.

The tester will start by mapping the application. This is where they’re gathering information like a normal website user—inspecting URLs, forms, API calls, etc.

They could be manually navigating these pages and inspecting network requests through the browser dev tools, looking for hidden endpoints and observing how those requests are structured.

Let’s say the tester finds a request:

POST /api/login
Content-Type: application/json

{
  "email": "user@test.com",
  "password": "123456"
}

They’ve now discovered an attack surface for authentication testing.

The tester will now explore whether they can move from a normal user account to a higher-privilege role. Through inspecting network requests or utilizing interceptors to modify these requests, let’s say they notice an API call:

GET /api/user/123

And they change it to:

GET /api/user/1

If user_id=1 belongs to an admin, access control is weak, and the system could then return real admin data. And if they modify the request body and the backend doesn’t have the necessary validations in place, the tester could now gain admin-level access.

Here, they could extract sensitive data like customer names, payment data, order history, etc.

Finally, they’ll prepare a document with an actionable report stating how the exposed API response and payload were used to breach a user’s account and even gain admin account access.

Benefits of penetration testing

“The true value of penetration testing lies not just in finding vulnerabilities, but in understanding how they could impact your business,” says Mark Burnett, a cybersecurity researcher and author.

1. Early detection of security weaknesses

Find and repair vulnerabilities before attackers exploit them. This approach enables you to correct security gaps before they become major breaks, saving both money and reputation.

2. Real-world risk assessment

Develop a solid awareness of your current security concerns. Practicing genuine attacks allows you to see exactly how attackers can target your systems and the damage they could cause.

3. Compliance validation

Regular testing ensures compliance with regulations such as GDPR, HIPAA, and PCI DSS while also providing evidence to demonstrate your security efforts.

4. Improved security awareness

Help your staff have a better understanding of security threats and responses. When employees observe actual examples of security flaws, they are more likely to comply with security rules and spot possible threats.

5. Cost-effective security

Early detection and resolution of vulnerabilities can help to avoid costly security breaches. The expense of frequent testing is significantly less than the potential financial impact of a serious security breach, which includes fines, legal fees, and lost revenue.

Early detection and resolution of vulnerabilities can help to avoid costly security breaches.

6. Enhanced customer trust

Show customers that you care about their security. Regular testing indicates your dedication to preserving client data, which can help you gain a competitive advantage and develop customer relationships.

7. Better decision-making

If you gather data that guides you clearly about the security investments, testing results assist you in prioritizing security spending and focusing resources on the most critical areas, ensuring that your security budget is spent efficiently.

Pen testing and compliance

Pen testing plays a critical role in helping organizations meet regulatory and industry compliance requirements. Many standards strongly recommend routine security testing to ensure that systems are resilient to real-world attacks.

1. PCI DSS (Payment Card Industry Data Security Standard)

Organizations that store and handle credit/debit card data of customers need to perform pen testing regularly to identify and fix any vulnerabilities in payment systems in order to ensure that transactions served by the system are completely secure.

2. HIPAA (Health Insurance Portability and Accountability Act)

This act mandates the protection of sensitive healthcare information. Through pen testing, organizations can validate if healthcare or medical data is secured against any breaches.

3. GDPR (General Data Protection Regulation)

GDPR is a European regulation that focuses on protection of personal data and privacy. It doesn’t explicitly mention pen testing, but it strongly encourages risk assessments and security testing to prevent any data leaks.

Failure to comply with these regulations can often have grave consequences for organizations, including financial penalties, legal consequences, etc. Pen testing can help ensure that organizations are part of a robust compliance strategy.

Challenges of penetration testing

“Every penetration test faces unique challenges, but the key is finding practical solutions that balance security needs with business operations,” notes Kevin Johnson, CEO of Secure Ideas.

1. Resource intensity

Complex testing demands a large amount of time and skill, which can put a strain on your resources. Organizations frequently struggle to strike a balance between extensive testing and preserving normal business operations, especially with limited security personnel.

2. Risk of system disruption

Testing can accidentally disrupt routine corporate operations or harm systems. Even well-planned tests might have unexpected effects on production systems, requiring careful coordination and backup procedures.

3. Incomplete coverage

It is challenging to test every possible scenario, so certain vulnerabilities may remain uncovered. Because IT systems are continually changing, even thorough testing may overlook some security flaws.

4. Keeping up with new threats

New attack strategies arise regularly, requiring the ongoing upgrading of testing procedures and tester knowledge.

5. Timing and scheduling

Determining the optimal time for rigorous testing without disrupting corporate activities can be challenging. Organizations must strike a delicate balance between security, business continuity, and customer service.

New attack strategies arise regularly, requiring the ongoing upgrading of testing procedures and tester knowledge.

Tools for penetration testing

Modern penetration testing relies on various specialized tools. Here are the key tools you should know about:

1. Nmap (Network Mapper)

Think of Nmap as a digital explorer for your network. It helps you discover what devices are connected to your network, what services they’re running, and what potential entry points exist for attackers.

This tool is particularly valuable because it can quickly scan large networks and provide detailed information about each discovered device, making it essential for the initial phases of security testing.

2. Wireshark

This tool is like a microscope for your network traffic. It captures and analyzes the data flowing through your network in real time, helping you spot suspicious activities, troubleshoot network problems, and identify security issues.

Security professionals use it to understand how their applications communicate and to detect any unusual or malicious network traffic patterns.

3. Metasploit

It serves as a complete toolkit for testing security vulnerabilities. It includes a collection of tested exploits, a database of known vulnerabilities, and tools for developing new security tests.

This platform helps security teams verify if their systems are vulnerable to specific attacks and understand how attackers might exploit these vulnerabilities.

4. Burp Suite

This tool specializes in testing web applications for security weaknesses. It acts as a security checkpoint between your browser and web applications, allowing you to intercept, analyze, and modify the traffic between them.

Burp Suite is particularly useful for finding common web vulnerabilities like SQL injection or cross-site scripting attacks.

5. Kali Linux

Kali Linux is an entire operating system built specifically for security testing, it comes pre-loaded with hundreds of security tools, making it a one-stop shop for penetration testers.

This system includes everything from password crackers to wireless network testers, making it an essential platform for security professionals.

What happens after a penetration test?

Once the entire process for the penetration test is complete, the first thing that happens is report analysis.

The tester shares a detailed report conveying what tests they performed, what vulnerabilities they found out, etc. Teams review this report and understand how to prioritize issues based on their severity.

Next, they start fixing these issues like patching the software, making their routes secure, authentication or access control more foolproof, etc. This is also known as remediation.

After the fixes are in place, the attacker performs retesting to verify that those fixes are actually effective.

Finally, teams can implement learnings from this security improvement cycle in their security roadmap and ensure that such issues are prevented in the future at development time of the system itself.

Penetration testing best practices

“The only truly secure system is one that is powered off, cast in a block of concrete and sealed in a lead-lined room.” – Gene Spafford (American Computer Scientist and Cybersecurity Pioneer)

To maximize the effectiveness of pentesting, teams should:

1. Test their own systems regularly—at least annually or twice in a year, usually after shipping any major updates in their software.
2. Utilize a combination of automated testing tools and manual testing to become more efficient at fixing security loopholes.
3. Use experienced testers to ensure the pen test has a wide coverage and is relevant with respect to modern security practices.
4. Prioritize remediation heavily so they can fix security issues as quickly as possible.

Conclusion

The success of your security systems is only as strong as your penetration testing strategy- without engaging in thorough testing of potential weak spots in your security systems, you and your team cannot provide the proper defenses against cyberattacks.

With knowledge of the testing method, its benefits, and problems, you can make more educated judgments about implementing penetration testing into your security plan.