Book Image

Web Penetration Testing with Kali Linux - Third Edition

By : Gilberto Najera-Gutierrez, Juned Ahmed Ansari
Book Image

Web Penetration Testing with Kali Linux - Third Edition

By: Gilberto Najera-Gutierrez, Juned Ahmed Ansari

Overview of this book

Web Penetration Testing with Kali Linux - Third Edition shows you how to set up a lab, helps you understand the nature and mechanics of attacking websites, and explains classical attacks in great depth. This edition is heavily updated for the latest Kali Linux changes and the most recent attacks. Kali Linux shines when it comes to client-side attacks and fuzzing in particular. From the start of the book, you'll be given a thorough grounding in the concepts of hacking and penetration testing, and you'll see the tools used in Kali Linux that relate to web application hacking. You'll gain a deep understanding of classicalSQL, command-injection flaws, and the many ways to exploit these flaws. Web penetration testing also needs a general overview of client-side attacks, which is rounded out by a long discussion of scripting and input validation flaws. There is also an important chapter on cryptographic implementation flaws, where we discuss the most recent problems with cryptographic layers in the networking stack. The importance of these attacks cannot be overstated, and defending against them is relevant to most internet users and, of course, penetration testers. At the end of the book, you'll use an automated technique called fuzzing to identify flaws in a web application. Finally, you'll gain an understanding of web application vulnerabilities and the ways they can be exploited using the tools in Kali Linux.
Table of Contents (19 chapters)
Title Page
Copyright and Credits
Packt Upsell

Chapter 6. Finding and Exploiting Cross-Site Scripting (XSS) Vulnerabilities

A web browser is a code interpreter that takes HTML and script code to present a document to the user in an attractive and useful format, including text, images, and video clips. It allows the user to interact with dynamic elements including search fields, hyperlinks, forms, video and audio controls, and many others.

There are many ways for an application to manage this dynamic interaction with users. The one way that is most common in today's web applications is the use of client-side script code. This means that the server sends code to the client that will be executed by the web browser.

When user input is used to determine the script code behavior, and this input is not properly validated and sanitized in order to prevent it from containing code, rather than information, the injected code will be executed by the browser and you will have a Cross-Site Scripting (XSS) vulnerability.

XSS is a type of code injection...