Web Application Security, 2nd Edition

Chapter 3. The Structure of a Modern Web Application

Before you can effectively evaluate a web application for recon purposes, it is best to gain an understanding of the common technologies that many web applications share as dependencies. These dependencies span from JavaScript helper libraries and predefined CSS modules, all the way to web servers and even operating systems. By understanding the role of these dependencies and their common implementations in an applications stack, it becomes much easier to quickly identify them and look for misconfigurations.

Modern Versus Legacy Web Applications

Today’s web applications are often built on top of technology that didn’t exist 10 years ago. The tools available for building web applications have advanced so much in that time frame that sometimes it seems like an entirely different specialization today.

A decade ago, most web applications were built using server-side frameworks that rendered an HTML/JS/CSS page that would then be sent to the client. Upon needing an update, the client would simply request another page from the server to be rendered and piped over HTTP. Shortly after that, web applications began making use of HTTP more frequently with the rise of AJAX (asynchronous JavaScript and XML), allowing network requests to be made from within a page session via JavaScript.

Today, many applications actually are more properly represented as two or more applications communicating via a network protocol versus a single monolithic ...