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)

Preventing HTTP response splitting

HTTP response splitting or CRLF injection is another injection vulnerability where the attacker can send an unfiltered HTTP request that includes a carriage return and line feed characters. Allowing a carriage return (%0d, in URL encoded form) and line feed (%0a, also in URL encoded form) in the request introduces a split in the HTTP response headers, thus changing the behavior of the ASP.NET Core web application. This HTTP response header modification can lead to the exploitation of many other vulnerabilities, such as open redirection or cross-site scripting, to name a couple.

In this recipe, we will prevent HTTP response splitting in our code by adding a validation check to the \n and \r characters.

Getting ready

Run the sample app to verify that there are no build or compile errors. In your command shell, navigate to the sample app folder at \Chapter12\crlf-injection\before\OnlineBankingApp and run the following command:

dotnet build...