One way we help to improve the security of WordPress plugins, not just for our customers of our service, but for everyone using them, is our proactive monitoring of changes made to plugins in the Plugin Directory to try to catch serious vulnerabilities. Through that, we caught a variant of those vulnerabilities, an authenticated PHP object injection vulnerability in the plugin Blog2Social, which has 70,000+ active installs according to wordpress.org.

We now are also running all the plugins used by customers through that on a weekly basis to provide additional protection for our customers.

The possibility of this vulnerability is also flagged by our Plugin Security Checker, so you can check plugins you use to see if they might have similar issues with that tool.

We tested and confirmed that our new firewall plugin for WordPress protected against the type of exploitation of this vulnerability you would see in a mass hack, even before we discovered the vulnerability, as part of its protection against zero-day vulnerabilities.

PHP Objection Injection

The automated portion of the proactive monitoring flagged the following line of code in the plugin:

602

 $myTimeSettings = unserialize(stripslashes($_POST['b2s-post-meta-box-best-time-settings']));

That will pass the POST input “b2s-post-meta-box-best-time-settings” through the unserialize() function, which would permit PHP objection injection to occur, which allows an attacker the ability to get code to run when not intended.

Whether there is a vulnerability would depend on who can access that.

That line of code is in the function b2s_save_post_box(), which is located in the file /includes/Loader.php. That function runs when saving a post:

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add_action('save_post', array($this, 'b2s_save_post_box'), 1, 3);

The code that runs in that function before getting to that line is a bit complicated, so we won’t go through it here, but the end result is that a WordPress user with the ability to publish posts, so those with the Author role and above, can access this. That means there is a vulnerability.

WordPress Causes Full Disclosure

As a protest of the moderators of the WordPress Support Forum’s continued inappropriate behavior we changed from reasonably disclosing to full disclosing vulnerabilities for plugins in the WordPress Plugin Directory 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. (For plugins that are also in the ClassicPress Plugin Directory, we will follow our reasonable disclosure policy.)

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).

If the moderation is cleaned up, it would also allow the possibility of being able to use the forum to start discussing fixing the problems caused by the very problematic handling of security by the team running the Plugin Directory, discussions which they have for years shut down through their control of the Support Forum.

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

With our plugin for testing for PHP object injection installed and activated, the following proof of concept will cause the message “PHP object injection has occurred.” be shown, when logged in to WordPress as an Author.

Access the plugin’s main admin page, /wp-admin/admin.php?page=blog2social, and agree to the privacy policy. Create a new post, add the following to the form for the post using your web browser’s developer tools, and attempt to publish the post.

<input type="hidden" name="b2s-enable-auto-post" value="1">
<input type="hidden" name="b2s-post-meta-box-sched-select" value="1">
<input type="hidden" name="b2s-post-meta-box-best-time-settings" value='O:20:"php_object_injection":0:{}'>
<input type="hidden" name="b2s-post-meta-box-profil-dropdown" value="1">
<input type="hidden" name="b2s-post-meta-box-profil-data-1" value="WyJwcm9vZm9mY29uY2VwdCJd">

Concerned About The Security of the Plugins You Use?