Arachni Web Application Scanner Web UI - Persistent Cross-Site Scripting

Title: Arachni Web Application Scanner Web UI Stored XSS Vulnerability
CVE: 2014-5469
Vendor Homepage: http://www.arachni-scanner.com/
Author: Prakhar Prasad
Author Homepage: https://prakharprasad.com
Reference: https://github.com/Arachni/arachni-ui-web/issues/71
Affected Version: Arachni v0.4.7/WebUI v0.4.4 (possibly in lower versions
too)
Date: August 17th 2014
Tested on: Arachni v0.4.7/WebUI v0.4.4 - Ubuntu 14.04


 Details
=======

This is an authenticated Stored XSS, hence the user needs to be logged in
to exploit this issue.

A malicious user (admin/regular) can initiate a website scan in the Arachni
Web UI. After initiating the scan, there is an option of users to comment
onto it (with Markdown formatting). However using Markdown the malicious
user can craft a link that will execute arbitrary Javascript once clicked.

The proof of concept XSS comment: [XSS](javascript:alert('XSS'))

The above comment will roughly translate into: <a
href="javascript:alert('XSS');">XSS</a>. Hence creating an anchor with
user-supplied Javascript content.