Yorick Koster, July 2016

Cross-Site Scripting in Contact Bank WordPress Plugin

Abstract

A Cross-Site Scripting vulnerability was found in the Contact Bank WordPress Plugin. This issue allows an attacker to perform a wide variety of actions, such as stealing Administrators' session tokens, or performing arbitrary actions on their behalf. In order to exploit this issue, the attacker has to lure/force a logged on WordPress Administrator into opening a malicious website.

Contact

For feedback or questions about this advisory mail us at sumofpwn at securify.nl

The Summer of Pwnage

This issue has been found during the Summer of Pwnage hacker event, running from July 1-29. A community summer event in which a large group of security bughunters (worldwide) collaborate in a month of security research on Open Source Software (WordPress this time). For fun. The event is hosted by Securify in Amsterdam.

OVE ID

OVE-20160724-0023

Tested versions

This issue was successfully tested on Contact Bank - Contact Forms Builder WordPress Plugin version 2.1.21.

Fix

This issue is resolved in Contact Bank version 2.1.23.

Introduction

The Contact Bank WordPress Plugin is a form builder plugin that lets you create contact forms in seconds with ease. A Cross-Site Scripting vulnerability was found in the Contact Bank WordPress Plugin. This issue allows an attacker to perform a wide variety of actions, such as stealing Administrators' session tokens, or performing arbitrary actions on their behalf. In order to exploit this issue, the attacker has to lure/force a logged on WordPress Administrator into opening a malicious website.

Details

The issue exists in the file views/header.php and is caused by the lack of output encoding on the page request parameter. The vulnerable code is listed below.

<script>
jQuery(document).ready(function()
{
   jQuery(".nav-tab-wrapper > a#<?php echo $_REQUEST["page"];?>").addClass("nav-tab-active");
});
</script>

Normally, the page URL parameter is validated by WordPress, which prevents Cross-Site Scripting. However in this case the value of page is obtained from $_REQUEST, not from $_GET. This allows for parameter pollution where the attacker puts a benign page value in the URL and simultaneously submits a malicious page value as POST parameter.

Proof of concept

<html>
   <body>
      <form action="http://<target>/wp-admin/admin.php?page=contact_dashboard" method="POST">
         <input type="hidden" name="page" value="</script><script>alert(1);</script>" />
         <input type="submit" value="Submit request" />
      </form>
   </body>
</html>