`------------------------------------------------------------------------
Cross-Site Scripting vulnerability in Email Users WordPress Plugin
------------------------------------------------------------------------
Yorick Koster, July 2016
------------------------------------------------------------------------
Abstract
------------------------------------------------------------------------
A Cross-Site Scripting vulnerability was found in the Email Users
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-20160712-0012
------------------------------------------------------------------------
Tested versions
------------------------------------------------------------------------
This issue was successfully tested on Email Users WordPress Plugin
version 4.8.2.
------------------------------------------------------------------------
Fix
------------------------------------------------------------------------
This issue is resolved in Email Users version 4.8.3.
------------------------------------------------------------------------
Details
------------------------------------------------------------------------
https://sumofpwn.nl/advisory/2016/cross_site_scripting_vulnerability_in_email_users_wordpress_plugin.html
The issue exists in the file email_users_user_settings.php and is caused by the lack of output encoding on the page request parameter. The vulnerable code is listed below.
<form id="email-users-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 $mailusersListTable->search_box(__('Search', MAILUSERS_I18N_DOMAIN), 'search_id'); ?>
<?php $mailusersListTable->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=mailusers-user-settings" method="POST">
<input type="hidden" name="page" value=""<script>alert(document.cookie);</script>" />
<input type="submit" value="Submit request" />
</form>
</body>
</html>
------------------------------------------------------------------------
Summer of Pwnage (https://sumofpwn.nl) is a Dutch community project. Its
goal is to contribute to the security of popular, widely used OSS
projects in a fun and educational way.
`
Data
Build on a solid foundation with Vulners data
We provide the essential building blocks for cybersecurity solutions with comprehensive, structured, and constantly updated vulnerability and exploits data
Api
Power your application with Vulners API
The Vulners REST API offers reliable, high-performance access to vulnerability intelligence, with 99.9% SLA uptime and CDN-backed data delivery for seamless global access
App
Assess and manage vulnerabilities with Vulners tools
Built on top of Vulners' database and SDK, end-user solutions give security professionals and developers lightweight and powerful tools for vulnerability remediation