Security Risk—XSS

Introduction to XSS

In our journey through web security, one of the most pervasive and potentially harmful vulnerabilities we come across is Cross-Site Scripting, commonly referred to as XSS. At its essence, XSS is a type of security vulnerability in web applications that enables attackers to inject malicious scripts into web pages viewed by other users. These scripts can then be executed in the context of the end user’s browser, leading to a variety of malicious outcomes.

As we navigate the digital realm, understanding the implications of XSS is paramount. Such attacks can lead to data theft, session hijacking, website defacement, and more. Protecting our web applications from XSS vulnerabilities requires a combination of secure coding practices, input validation, and staying updated with the latest security patches and recommendations. It’s a collective effort on our part to ensure the web remains a safe space for all its users.

By making coding mistakes, we can allow malicious attackers to exploit some of our features to steal or modify our users’ data. This is part of a larger theme in software development: security, a critical aspect that must never be overlooked.

Whether it’s the accidental inclusion of a malicious library or the lack of proper validation in user input, small oversights can lead to significant vulnerabilities. In this lesson, we’ll explore a specific security concern related to user-generated content, which is becoming increasingly common in modern web applications.

Cross-Site Scripting, or XSS, has been in the OWASP Top Ten every year for the past decade, and in 2022 has reached the third position. Let’s examine the following image and explore step by step how an XSS attack can take place:

Step-by-step explanation of the image is provided below:

1. The attacker realizes that there is an XSS vulnerability in our application, so they write a malicious script code and add it where our vulnerability exists, most likely in a comment form.

2. The malicious code is then sent to the server, probably in our database with the rest of the comments.

3. When a normal user visits our application and wants to read a comment, they request the comments from our database. The malicious code introduced by ...