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)

Chapter 5: XML External Entities

eXtensible Markup Language (XML) is a standard markup language that's used to define data. XML is also a format that an ASP.NET Core web application can use to parse information. To achieve this, a developer can use any number of .NET XML parsers readily available in the framework.

XML being a source of input is likely to be prone to malicious data injection. A feature called XML External Entity (XXE) allows XML to define a custom entity using a URL or file path. This ability to represent external entities in XML can be abused or exploited. Unrestricted external entity references can allow attackers to send sensitive information and files outside the applications' trusted domains and into the perpetrator-controlled server. The existence of this vulnerability can lead to Denial-of-Service (DoS) attacks, making the whole application inaccessible because of flooded requests, or file inclusion attacks, where an adversary can gain unauthorized...