Mastering Web App Penetration Testing: Your Ultimate Guide

Despite the influx of technological and digital advancements, data breaches still remain a problem in today’s world. With cybercrime on the rise, protecting your web applications and the data stored in it is of utmost importance.

But how to ensure that your data is protected at all costs? Web application penetration testing is one way to go about it. It is a simulated ethical hacking tool that lets you identify vulnerabilities in your web app before malicious parties can exploit them.

So, keep on reading this blog to know more about the core components that need to be considered, how it works, and what tools to use. As a cyber essentials certified company, GoodCore is here to bring the latest insights for tackling vulnerabilities in your app before they become a huge problem.

What Is Website Penetration Testing?

Website penetration testing, or web application penetration testing, involves simulating a cyberattack against a web app to identify its vulnerabilities. The main goal of such testing is to find those weak spots before malicious actors can exploit them.

The vulnerabilities may include security misconfigurations, coding errors, flaws in application logic, and beyond. Checking for them regularly helps developers and security professionals decide whether corrective actions and additional security measures are necessary.

If you are still in the planning phase of your app, check out our comprehensive web application development guide.

Types of Website Penetration Testing

Website penetration tests can be categorised based on different approaches, targets, and environments. Understanding these types will help you choose the right strategy depending on your application’s interface, data compliance requirements, and threat model.

Penetration Testing by Approach

This type of testing is further classified into three categories, depending on how much information the tester has about the system.

Black Box Testing

In black box testing, the tester has no prior knowledge of the system’s internal workings. It simulates a real-world external attack, where the tester behaves like a hacker trying to break in from the outside without any insider information. This method is great for assessing how secure your web app is from unknown attackers.

White Box Testing

White box testing, also known as clear box testing, involves full access to the system’s source code, architecture, and documentation. This approach allows testers to dig deep into the application to identify vulnerabilities that may not be apparent from the outside. It’s typically used in secure SDLC (Software Development Life Cycle) processes to ensure that all vulnerabilities are thoroughly detected. 

Gray Box Testing

Gray box testing offers a middle ground, in which the tester has limited knowledge of the system. This approach combines the benefits of both black and white box methods and often reflects the perspective of an attacker who has gained some access or credentials (like a logged-in user).

Penetration Testing by Target

Depending on what is being tested, penetration tests can be done on different components of the infrastructure, like:

Web Application Testing

This is the most common type when it comes to websites. It focuses on identifying vulnerabilities within the application itself, such as SQL injection, XSS, CSRF, authentication issues, and insecure APIs.

Network Penetration Testing

This targets network infrastructure (internal or external) to identify weaknesses like open ports, unpatched systems, and insecure network protocols. It helps ensure that hackers can’t exploit network-level vulnerabilities to gain unauthorised access to critical systems or sensitive data.

Wireless Network Testing

This test checks for vulnerabilities in wireless networks. For example, weak encryption or rogue access points, that could allow attackers to infiltrate the internal systems. It is particularly important for organisations with remote access points or BYOD policies, where wireless security is often a weak link.

Penetration Testing by Location

The third type of penetration testing is defined by where the attack is stimulated from. 

External Testing

This test simulates an attack from outside the organisation’s network, as if an external attacker was trying to gain unauthorized access to the system. The target is the organisation’s publicly accessible assets such as the website, web servers, DNS, or firewalls. This type of test helps assess how exposed your systems are to external threats.

Internal Testing

In contrast, internal testing is performed from within the organisation’s network. It mimics an insider whose credentials were compromised or an attacker who has gained limited access.

Blind Testing

Here, the testing team is provided with minimal or no information beforehand. It simulates a real-world scenario where attackers spend time gathering intel before launching an attack.

Double-Blind Testing

In this case, even the internal security team is unaware of the planned test. It is useful for testing not only the security of systems but also how well your incident response team reacts when threats occur in real-time.

Phases of Penetration Testing

Web app pentesting follows four key phases: reconnaissance, mapping, vulnerability assessment, and exploitation. Let’s get each of them straight:

1. Reconnaissance. In this initial phase, the tester gathers information about the target system, including its purpose, network topology, technology stack, user accounts, and other relevant details. This involves researching OSINT and other publicly available sources.
2. Mapping. Once all the relevant data is collected, the tester continues exploring the target system. They may use various tools (Nmap, Shodan, DNSDumpster) to identify open ports and network traffic to better understand the system’s architecture and potential attack surfaces.
3. Vulnerability assessment. The next phase is where the tester uses the discovered data to identify specific weaknesses within the system. Then, they decide on how to exploit the vulnerabilities.
4. Exploitation. In this phase, the tester attempts to exploit the identified vulnerabilities to access the system or its data, typically by using tools like Metasploit. This stage lets the tester evaluate the severity of the system weaknesses and the potential impact of a real-world attack.

How to Conduct Website Penetration Testing Step-by-Step

Now that you know the web app penetration meaning and components, let’s explore the practical steps involved. Here’s how our experts at GoodCore prepare and conduct web application security testing:

Step 1: Set Up Your Testing Environment

Before actually hacking the web app, you should prepare a solid foundation. Here is what you need to get started:

• Define the scope. Set the boundaries of your penetration test. Decide on the specific web app aspects you’ll be checking and the testing methods you’ll use. Outline the desired outcomes and goals of the test (e.g., ensure compliance or evaluate overall app protection).

• Gather information. The more you know about your target application, the more effective your testing will be. Go through the reconnaissance phase and collect info about the tech stack, app features, network and domain names, and any known vulnerabilities.

• Select necessary tools. Equip yourself with the tools necessary for the job. They may include vulnerability scanners, web app security testing software, or specialised penetration testing software.

Step 2: Threat Modelling and Planning

Identify potential attack vectors, such as user input fields, APIs, third-party integrations, and access controls, and prioritise them based on their risk levels.

This step helps simulate realistic attack scenarios by designing targeted test cases that reflect how real-world attackers might exploit vulnerabilities in your specific web application environment. It also ensures that your testing efforts are focused on the most critical and high-impact areas.

Step 3: Automated and Manual Testing

Start by running automated vulnerability scanners to identify common issues like outdated libraries or misconfigurations. These tools can help cover a broad range of vulnerabilities in a short time. However, there is one flaw, that is they often miss complex, context-specific flaws.

After you have scanned for vulnerabilities, follow up with manual testing to thoroughly assess business logic errors, broken access control, insecure authentication flows, and other nuanced weaknesses that automated tools may overlook. 

Step 4: Exploitation

With vulnerabilities identified and confirmed, the next step is to ethically attempt exploitation, which should always be within the agreed scope and rules of engagement.

In step, you are basically testing how far the vulnerability can be leveraged: Can it lead to unauthorised access, exposure of sensitive data, or even a complete system compromise? How big of a problem would these vulnerabilities be and how urgently do they need to be fixed?

Step 5: Post-Exploitation Analysis and Reporting

After the exploitation phase, compile your findings into a clear, actionable penetration testing report. It should include the steps taken, tools used, vulnerabilities discovered, how severe they are, and any successful exploit attempts.

Where applicable, provide proof-of-concept (PoC) examples or screenshots to illustrate how the vulnerabilities were exploited. Finally, include the detailed remediation recommendations to help your development team fix the issues and prevent similar ones in the future.

Feeling overwhelmed? Let our experienced team handle web app penetration testing for you.

Importance of Web Penetration Testing

Web application pen testing helps you check every part of your app: its database, frontend, and backend. Here are several reasons why this is important:

• Data security. Web application pentesting is a way of protecting sensitive data from unauthorised access, modification, or deletion.
• Reduced risk of breaches. Penetration testing identifies and addresses loopholes in your web app so that it can withstand cyberattacks.
• Regulatory compliance. Web app pen testing helps you comply with industry regulations and security standards, including PCI DSS, HIPAA, etc.
• Infrastructure assessment. Penetration testing lets you evaluate the strength of public-facing infrastructure components like firewalls and DNS servers.

Essential Tools and Techniques for Penetration Testing

You need various website penetration testing tools to handle the tests successfully. Let’s see what exactly you can leverage.

Popular Tools Used in Penetration Testing

To test your web application, it’s necessary to install apps and tools for penetration testing. Their selection is extensive:

• ZAP. It’s an open-source web application security scanner suitable for beginners and experienced testers alike. ZAP provides a user-friendly interface for manual testing and offers automated scanning as well.
• Burp Suite. It’s a comprehensive suite of tools for web application vulnerability assessment and penetration testing. It lets you identify vulnerabilities, automate attack sequences, scan APIs and SPAs, and minimise false positives.
• Metasploit. It’s a web application penetration testing framework that lets you develop and execute exploit code against a target system. It offers an extensive database of exploits and payloads, tools for manual exploitation, phishing awareness management, and other features.
• Nmap. It’s a network mapping tool that allows you to discover hosts and services on a computer network, thus providing a map of the network’s structure. It identifies open ports, operating systems, ping sweeps, and more.
• Shodan. It’s a search engine for Internet-connected devices, which lets you find information about devices (webcams, routers, servers) that are publicly accessible. It helps you get insights into the exposed services and their potential weaknesses.
• DNSDumpster. It’s a tool used for DNS reconnaissance. You can get an overview of subdomains, mail servers, name servers, and other relevant DNS records.

The tech stack you choose can influence the types of vulnerabilities your app may face. If you would like to know more about the pros and cons of different stacks from a development and security perspective, read our blog on popular web technologies.

Manual vs. Automated Testing

Manual and automated testing are both necessary for a comprehensive check of your web app. Here’s a breakdown of their strengths and weaknesses:

Penetration Testing Best Practices

To get the most value from your testing efforts, reduce risk, and ensure accurate, actionable results, it is essential to follow a set of proven best practices. And, so we have gathered the top seven practices from industry experts to help you ensure a successful and secure penetration process: 

1. Always Get Legal and Executive Approval: Never begin testing without formal consent. Define the rules of engagement clearly to avoid legal and operational issues.

2. Test in a Controlled Environment: Avoid testing live production environments unless explicitly agreed upon. Use staging environments wherever possible.

3. Combine Automated and Manual Testing: While tools speed up the process, human testers can uncover complex issues that scanners miss.

4. Follow a Clear Rectification Plan: Testing is just the beginning. Make sure vulnerabilities are patched and re-tested. Prioritise based on how severe the vulnerability is.

5. Document Everything: Maintain detailed logs, test steps, and outcomes. These documents are vital for audits, compliance, and developer remediation.

6. Repeat Testing Regularly: New threats emerge constantly. Schedule regular penetration tests—especially after major updates or new feature deployments.

7. Stay Updated with the OWASP Top 10: Ensure your web app is regularly tested against the most critical security risks outlined by OWASP.

Read also: How to optimise your web app development costs

How GoodCore Can Help with Web App Penetration Testing

GoodCore has been recognised as one of the top web development companies in London thanks to our decades of experience and the unparalleled web app development services. The applications we build are secure, compliant, and always tailored to our client’s requirements. Here’s how we make that possible:

• Highly skilled web app developers using the latest tech stack.
• Efficient project management to deliver your app on time and within budget.
• Flexible team to meet any of your evolving demands.
• Keeping you updated throughout the process.

Offering end-to-end web application development, we handle thorough testing along the way. In particular, we conduct security checks, with penetration testing as part of them. Our web application penetration testing checklist includes:

• Defining the testing scope. We identify which parts of your web app will be tested, along with your goals and desired outcomes.
• Collecting the info on your app. We study your app’s tech stack, features, and architecture.
• Assessing the vulnerabilities. We identify security weaknesses in your web app through automated and manual testing.
• Exploiting the vulnerabilities. We try to exploit the identified vulnerabilities in a controlled environment to understand their potential impact.
• Suggesting remediation scenarios. Based on the testing results, we provide recommendations on how to fix the discovered vulnerabilities.

Since cybersecurity is developing rapidly, GoodCore aims to stay ahead of the curve. Recently, our team was evaluated and certified by Cyber Essentials, a UK-based vendor supported by the National Cyber Security Centre (NCSC). Therefore, we are knowledgeable about the most effective ICT defences against common cyber threats.

One recent example of our work is BriefingSource, a briefing management platform. The client set high standards for data security and privacy, requiring their product to comply with GDPR and SOC2/Type2 regulations. To meet these requirements, we implemented authorised access and single sign-on mechanisms, identity management, data encryption, regular security audits, and comprehensive privacy policies. As part of this project, we also handle quarterly penetration tests.

Conclusion

In the face of rising data breaches, web penetration testing has become an invaluable security measure. By following our guide on how to do penetration testing for a website or app and combining manual and automated testing techniques, you’ll be able to improve your web application’s security posture.

In case you want to secure help from professionals, you can count on GoodCore’s many-year experience to achieve the utmost security of your software. Just drop us a line to discuss your specific needs.

FAQs

What should I do after a web application penetration test?

First, you create a report with all the identified vulnerabilities, ranking them by their severity, impact, and ease of exploitation. Then, you need to develop a remediation plan — the steps you should take to fix the issues. After remediation, conduct application pen testing once again to ensure all vulnerabilities have been successfully tackled.

How often should I conduct web application penetration testing?

Generally, it’s best to handle web app pen testing at least once or twice a year. Besides just regular checks, perform a test whenever there are significant changes to the application or after a security incident or breach.

Can a pen test damage my web application?

Website penetration testing is generally safe. Yet, there’s a small risk of damage, especially if the test involves aggressive scanning or exploitation. To avoid any risks, make sure that the website penetration testing service is performed by professionals — best if they’re certified.

What are some limitations of web application penetration testing?

While penetration testing of websites or web apps is increasingly helpful, it has certain limitations. They are:

• Scope constraints. Penetration tests are limited by the pre-defined scope, which may not cover all potential attack vectors.
• False positives. Automated testing tools may suggest false positives (non-issues marked as vulnerabilities), so you must check everything manually.
• Human factor. The test’s effectiveness and accuracy depend on the skills of the testers, which may vary.

What are some alternatives to web application penetration testing?

If, for some reason, a penetration test of a web application isn’t suitable for you, you can opt for several alternatives. Those include automated vulnerability scanning, manual or automated code reviews, security audits, automated breach simulations, and using CI/CD security tools.