How to Perform a Web Application Pentest

How to Perform a Web Application Pentest with Burp Suite and Katana​

Introduction​

Web application pentesting is a crucial aspect of cybersecurity, and using specialized tools like Burp Suite and Katana allows security professionals to identify vulnerabilities efficiently. This advanced guide will explore how to integrate these tools into a pentesting workflow to evaluate the security of a web application.

In this article, we will cover:
Setting up a test lab for practical exploitation.
Using Katana for hidden route discovery and endpoint enumeration.
Exploiting vulnerabilities using Burp Suite.
Advanced techniques for bypassing security protections.

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1. Setting Up the Testing Environment​

Before performing a pentest, we need a controlled environment to conduct security tests legally and safely.

Requirements​

• Operating System: Kali Linux or Ubuntu with required tools installed.
• Tools:
  • Burp Suite (Community or Professional version)
  • Katana (ProjectDiscovery)
  • OWASP Juice Shop (a deliberately vulnerable web application)
• Browser: Firefox with FoxyProxy extension for traffic interception.

Installing Katana​

To install Katana, execute the following commands in Kali Linux:


Verify the installation with:

Setting Up OWASP Juice Shop​

This will start a vulnerable web application at

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.

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2. Discovering Hidden Routes with Katana​

The first step in a pentest is to map the attack surface. Katana helps us find hidden routes and exposed API endpoints.

Run the following command:

Explanation of parameters:​

• -u: Target URL.
• -d 3: Scan depth (adjustable).
• -o: Saves results to a file.

Now, analyze the discovered paths:

If we find sensitive endpoints like /admin or /api/secret, we can investigate them further using Burp Suite.

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3. Configuring Burp Suite for Traffic Interception​

Setting Up the Proxy​

1. Open Burp Suite and go to Proxy > Options.
2. Ensure the proxy is active on 127.0.0.1:8080.
3. Configure FoxyProxy in the browser to forward traffic through Burp Suite.

Now, every request made in the browser will be intercepted by Burp.

Intercepting Requests and Modifying Parameters​

Access Juice Shop and browse different pages. In Burp Suite > Target > Site Map, look for interesting endpoints.

Example of a login request interception:

Now, let's modify the parameters to perform SQL injection:

If access is granted without the correct password, we have found a SQL injection vulnerability.

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4. Exploring and Exploiting Vulnerabilities​

Fuzzing with Burp Intruder​

Automate attacks using Burp Intruder:

1. Capture a request with parameters in Burp Proxy.
2. Send it to Intruder.
3. Select a parameter to attack (e.g., email).
4. Load a wordlist (/usr/share/wordlists/rockyou.txt).
5. Run the attack and analyze HTTP responses.

If a response returns 200 OK instead of 401 Unauthorized, we have found valid credentials.

Example of an XSS Exploit​

If a web form does not properly validate input, we can inject a Cross-Site Scripting (XSS) payload:

If this script executes in the browser, the application is vulnerable to XSS.

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5. Reporting and Mitigating Vulnerabilities​

After identifying security flaws, we must create a detailed security report.

Example: SQL Injection Vulnerability Report​

Title: SQL Injection in /api/login endpoint
Severity: High
Impact: Allows authentication bypass and access to sensitive data.
Steps to reproduce:

1. Send the following payload in the login request:
   
   HTTP:

   {"email":"admin' OR 1=1--","password":"password"}

2. User logs in without providing a valid password.

Recommendations:

• Use parameterized queries to prevent SQL injection.
• Implement input validation and Web Application Firewall (WAF).

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6. Conclusion​

In this advanced pentesting guide, we have successfully integrated Katana and Burp Suite into an ethical hacking workflow:
Discovered hidden endpoints using Katana.
Intercepted and modified HTTP requests using Burp Suite.
Exploited SQL Injection and XSS vulnerabilities.
Created a security report with mitigation steps.

Next Steps:​

• Learn WAF bypass techniques.
• Automate scans with Burp Suite Extensions.
• Conduct a real-world pentest with proper authorization.

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