Chapter 1. Introduction to Attacking Web Applications

Web applications are everywhere. They are part of the fabric of society and we depend on them in many aspects of our lives. Nowadays, they are easy to develop, quick to deploy, and accessible by anyone with an internet connection.

The technology designed to help develop and deploy web applications has also boomed. New frameworks that enhance functionality and usability are released daily. Companies have shifted power to the developer, allowing them to be more agile and produce web applications quickly.

The following figure gives a taste of the more popular development environments and frameworks that have taken the application development world by storm. Node.js has brought the browser client scripting language JavaScript to the server-side, complete with a massive library of modules to aid in fast application development. JavaScript, a once seldom-used scripting language for the browser, is supercharged on the client-side with React and Angular, and is even available for cross-platform development with the likes of Electron and Chromium:

Figure 1.1: The world has changed since Netscape ruled online and this graphic shows but a taste of the technologies that dominate the web today

GitHub has become the one-stop shop for open-source libraries, applications, and anything a developer may want to share with the world. Anyone can upload anything they want and others can collaborate by pushing code changes or saving a dying codebase, by forking it and continuing development locally. GitHub is not alone, of course, as there are similar repositories for Node.js, Python, and PHP modules.

The developer's focus is always on getting the product shipped, whether it's a simple feature implementation in an internal web application used by the marketing department, or the latest and greatest web banking interface. The infrastructure required to support these applications has also evolved and developers struggle to integrate security into their workflow. It's not always ignorance that hurts secure application development, however. More often than not, time constraints and deadlines are to blame.

The goal of this book is to showcase how attackers view web applications and how they take advantage of weaknesses in the application code and infrastructure. We will consider all the common mistakes made during the development process that are used to gain meaningful access. We will look at practical attacks and making the most of common application vulnerabilities.

Some assumptions about your knowledge level are made. To get the most value out of reading this book, a basic knowledge of application security should be there. Readers do not have to be experts in the field of penetration testing or application security, but they should have an idea about what cross-site scripting (XSS) or SQL injection (SQLi) attacks are. We will not devote a chapter to the standard "Hello World" example for XSS, but we will show the impact of exploiting such a vulnerability. The reader should also be familiar with the Linux command prompt and common console tools, such as curl, git, and wget. Some familiarity with programming will certainly help, but it is not a hard requirement.

In this chapter, we will cover the following topics: