Cross-site scripting (XSS), (DOM based reflected via AJAX request) - DOM Based (javascript in fragment)

DOM-based Cross-Site Scripting is the de-facto name for XSS bugs which are the result of active content on a page, typically JavaScript, obtaining user input and then doing something unsafe with it to lead to execution of injected code. This document will only discuss JavaScript bugs which lead to XSS.

The DOM, or Document Object Model, is the structural format that may be used to represent documents in the browser. The DOM enables dynamic scripts such as JavaScript to reference components of the document such as a form field or a session cookie. The DOM is also used by the browser for security - for example to limit scripts on different domains obtaining session cookies for other domains. A DOM-based cross site scripting vulnerability may occur when active content, such as a JavaScript function, is modified by a specially crafted request such that a DOM element that can be controlled by an attacker.

There have been very few papers published on this topic and, as such, very little standardization of its meaning and formalized testing exists.