How to Break Into Web Application Security (2025)

Introduction

Have you ever wondered where to start in web application security? Are you aspiring to become a web application penetration tester? This blog will guide you in the right direction to begin your web application security journey.

What is Web Application Security

Web applications are one of the primary entry points for cybercriminals targeting a company. There is sensitive data stored in each application we see on the internet. These applications are prone to threats every day, and the way to secure them is by having regular penetration tests to ensure proper security controls are in place. Here are a few common threats we encounter in web application security:

• SQL Injection: Obtaining access to the database by exploiting queries executed on the backend.
• Cross-Site Scripting (XSS): Executing malicious JavaScript on an application can lead to session stealing or session riding.
• Insecure Direct Object References (IDOR): Access unauthorized information from an account.

These are just a few basic examples, and we will dive into each individually in upcoming blogs.

Build a Solid Foundation

Before getting into the fun stuff, you will need a basic understanding of how the web works. This will make it easier for you to identify vulnerabilities in the long term, help you think like a developer, and understand their goals.

Learn Web Requests and The Protocol

You will need to understand the difference between HTTP and HTTPS and why HTTP is less secure than HTTPS. Each time you visit a website, two things happen: requests and responses. This is how the web server communicates from the backend to the front end to display data.

Here’s an example:

A login page has two input fields: a username and a password. After clicking the submit button, a request is sent to the server and processed on the backend. The web server sends a response that indicates whether the username and password are correct.

While this is a basic example, it happens on every web page you visit. In addition to each response, a status code indicates whether the web request was successful. Here are a few essential codes to take note of:

• 200 OK - This code refers to the valid request.
• 302 Redirect - Redirects the end-user to a different website or part of the application.
• 404 Page Not Found - The page doesn’t exist on the web server.
• 500 Internal Server Error - Something happened that resulted in the server being unable to process the request correctly.

Learning Basic Implementation of Code

Familiarizing yourself with the basics of HTML and JavaScript will help you understand how a web application is laid out. All HTML tags can be used to perform malicious actions on an application, so it is important to understand what each tag does and the different attributes that can be used with it.

If you want to go deeper, look into common web application frameworks such as Django, Flask, Gin, and ASP.NET. Understanding these frameworks will help you familiarize yourself with backend logic and how security mechanisms are implemented. This foundational knowledge will allow you to identify potential security threats when assessing similar applications quickly.

Learn By Doing

There are some fantastic resources to assist with your development and understanding of the web. TryHackMe does a fantastic job outlining how the web works, Burp Suite, and the basics of web application hacking. I recommend checking it out.

Additionally, PortSwigger, the creators of Burp Suite, do a great job of giving you an in-depth understanding of different vulnerabilities, how they affect organizations, and how to attack applications. They provide labs that give a real-world feel to each vulnerability. This entire platform is free to use and explore (some labs may require a Burp Pro license).

Learn Proper Tooling

While there are many tools out there, here are three that I use while working on an engagement:

Burp Suite

Utilizing Burp Suite will be essential when performing a web application security assessment. This tool allows you to proxy traffic and see the communication between the user’s interaction and webserver. Burp Suite has many modules, such as Repeater, Intruder, Collaborator, and Extensions.

SQLMap

SQLmap is an automated tool that helps identify SQL Injections. This tool is dangerous, as you don’t know what is happening in an application’s backend, so use caution. However, it does a fantastic job identifying SQL Injections and dumping databases. SQLmap comes with its own style of writing payloads, and you can make custom tamper scripts to assist SQLmap in identifying difficult SQL Injections.

Gobuster

While performing a penetration test, you may be stuck and need to start enumerating different directories on the web server. Gobuster will do that and provide information about live files and directories stored on the web server. There could be backups, configuration, or other files you shouldn’t have access to.

Conclusion

Getting started in web application security can be daunting, but remember, everyone has to start somewhere. It may take several months to understand common vulnerabilities in a web application. Practice on TryHackMe or PortSwigger, where they go over the basics to more advanced vulnerability types.

Everything in this blog is for educational purposes only. Do not use against targets that don’t permit you.