Book Image

ASP.NET Core 5 Secure Coding Cookbook

By : Roman Canlas
Book Image

ASP.NET Core 5 Secure Coding Cookbook

By: Roman Canlas

Overview of this book

ASP.NET Core developers are often presented with security test results showing the vulnerabilities found in their web apps. While the report may provide some high-level fix suggestions, it does not specify the exact steps that you need to take to resolve or fix weaknesses discovered by these tests. In ASP.NET Secure Coding Cookbook, you’ll start by learning the fundamental concepts of secure coding and then gradually progress to identifying common web app vulnerabilities in code. As you progress, you’ll cover recipes for fixing security misconfigurations in ASP.NET Core web apps. The book further demonstrates how you can resolve different types of Cross-Site Scripting. A dedicated section also takes you through fixing miscellaneous vulnerabilities that are no longer in the OWASP Top 10 list. This book features a recipe-style format, with each recipe containing sample unsecure code that presents the problem and corresponding solutions to eliminate the security bug. You’ll be able to follow along with each step of the exercise and use the accompanying sample ASP.NET Core solution to practice writing secure code. By the end of this book, you’ll be able to identify unsecure code causing different security flaws in ASP.NET Core web apps and you’ll have gained hands-on experience in removing vulnerabilities and security defects from your code.
Table of Contents (15 chapters)

Fixing DOM XSS

The Document Object Model (DOM) is an object interface that represents an HTML page. This interface allows client-side scripts to manipulate, add or remove elements from the document. The client-side script used in conjunction with the JavaScript programming language can be written insecurely and opens up security vulnerabilities such as DOM-based XSS.

DOM XSS, in contrast to reflected and stored XSS, is not a server-side exploit. The weakness is in the client-side code when it attempts to modify the DOM to display data, but instead interprets the input into code due to a lack of encoding and proper escaping. In this recipe, we will fix the DOM-based XSS vulnerability by using an encoding function from a JavaScript library.

Let's now see in action how a DOM XSS vulnerability can be tested.

Testing DOM XSS

Here are the steps:

  1. Navigate to Terminal | New Terminal in the menu or simply press Ctrl + Shift + ' in Visual Studio Code.
  2. Type...