KNOXSS is an online XSS tool with demonstration of vulnerability (PoC - Proof of Concept). It's still under development, being launched as beta. Currently it supports source and DOM based reflected XSS, although by chance a stored or a more complex DOM-based case may arise if there's also a reflection in response. Except for demo plan (below), it also drops (in certain cases) a XSS payload designed to send an email report to KNOXSS user with info about the environment where it was triggered (in scenarios where such vulnerability exists) hence also being able to find blind and stored XSS cases in this way.
It has 3 plans: Demo, Standard and Pro.
A completely free version to show the way KNOXSS works, with reflection finding and PoC generation using the most common and useful single XSS vector/payload. A lot of XSS flaws can be found with this simplest version, either using GET or POST HTTP methods.
The core engine of KNOXSS with possibility to send authenticated GET or POST requests by means of HTTP headers provided by user. For PoC it uses 2 specially crafted XSS polyglots (one for source and another for DOM based XSS), designed to work in majority of XSS scenarios with basic filter bypass capabilities. It comes with a Mozilla Firefox extension that can scan for forms and send to main interface the target page where user currently is, for XSS tests. It performs very well against almost all targets.
With multiple vectors and decision-making capabilities, KNOXSS Pro is able to find a lot of edge XSS cases and bypass more filters. It also has an extension that makes all the job completely automatic: after setting a domain with one click, all URLs and forms navigated in all subdomains will be submitted to KNOXSS for testing.
Standard and Pro comes with a Mozilla Firefox addon (currently outdated but fully functional) designed to send target info to KNOXSS service while user navigates. It also grabs all form fields of the current page for additional tests.
Because KNOXSS actually checks for vulnerabilities using Gecko engine and pops a window with PoC, we strongly recommend the use of Mozilla Firefox browser for the intended experience.
All XSS vulnerabilities (cases) which can be found by KNOXSS are in the KNOXSS Extension Test Page.
An old video with both Standard and Pro Firefox extensions in action is below. Read also our FAQ.