01 Sep

What Happened With WordPress Plugin Vulnerabilities in August 2017

If you want the best information and therefore best protection against vulnerabilities in WordPress plugins we provide you that through our service.

Here is what we did to keep those are already using our service secure from WordPress plugin vulnerabilities during August (and what you have been missing out on if you haven’t signed up yet):

Plugin Security Reviews

Customers of the service can suggest and vote on plugins to have a security review done by us. This month we released details for a review of:

We don’t currently have any more plugins queue up for a review, so if you sign up now for the service, a plugin you suggest could be reviewed right away.

Plugin Vulnerabilities We Discovered and Publicly Disclosed This Month

We don’t just collect data on vulnerabilities in plugins that others have discovered, we also discover vulnerabilities through proactive monitoring of changes made to plugins, monitoring hackers activity, reviewing other vulnerabilities, and by doing additional checking on the security of plugins.

This month the most concerning vulnerability is a PHP object injection vulnerability in WP Smart Security, since that type of vulnerability is likely to be exploited and the vulnerability hasn’t been fixed yet.

Plugin Vulnerabilities We Helped Get Fixed This Month

Letting you know that you are using a vulnerable version of plugin is useful, but it is much more useful if you can fully protect yourself by simple updating to a new version. So we work with plugin developers to make sure that vulnerabilities get fixed. This month we helped to get vulnerabilities fixed in plugins that have 177,800+ active installs:

Plugin Vulnerabilities Added This Month That Are In The Current Version of the Plugins

Keeping your plugins up to date isn’t enough to keep you secure as these vulnerabilities in the current versions of plugins show:

Additional Vulnerabilities Added This Month

As usual, there were plenty of other vulnerabilities that we added to our data during the month. Most of the new vulnerabilities that were fixed this month are relatively minor.

17 Aug

PHP Object Injection Vulnerability in Leaky Paywall

We recently started proactively monitoring for evidence of some high risk vulnerabilities when changes are made to WordPress plugins and if we had more customers we could expand the proactive monitoring to more types of vulnerabilities. One of the types of vulnerabilities we are looking for are PHP object injection vulnerabilities since those are likely to be exploited if hackers become aware of them. Through that we came across a PHP object injection vulnerability in the plugin Leaky Paywall, which permits implementing a paywall on a website.

That a plugin used for business purposes has a serious vulnerability is all too common in our experience and is good reminder of the value of getting a security review of plugins that business can make a lot of sense. Through our service, paying customers can suggest and vote for plugins to have a review done. We also recently introduced the option to purchase the same type of review for a plugin of your choice.

The plugin makes the function process_cookie_requests() available through WordPress AJAX functionality whether the request comes from someone that is logged in to WordPress or not (/include/class-restrictions.php):

add_action( 'wp_ajax_nopriv_leaky_paywall_process_cookie', array( $this, 'process_cookie_requests' ) );
add_action( 'wp_ajax_leaky_paywall_process_cookie', array( $this, 'process_cookie_requests' ) );

In the process_cookie_requests() function, if the cookie “issuem_lp” exists its value would be unserialized, which permits PHP object to occur:

if ( !empty( $_COOKIE['issuem_lp'] ) ) {
	$available_content = maybe_unserialize( stripslashes( $_COOKIE['issuem_lp'] ) );

There was similar code in the function process_requests() in the file /class.php, which may also be vulnerable.

After we notified the developer of the issue they released version 4.9.2, which resolves the vulnerability by replacing the usage serialization and unserialization with JSON encoding and decoding.

Proof of Concept

With our plugin for testing for PHP object injection installed and activated, set the value of the cookie “issuem_lp” to “O:20:”php_object_injection”:0:{}” and then when you visit the following URL  the message “PHP object injection has occurred.” will be shown.

Make sure to replace “[path to WordPress]” with the location of WordPress and “[valid post ID]” with the ID number of a valid post.

http://[path to WordPress]/wp-admin/admin-ajax.php?action=leaky_paywall_process_cookie&post_id=[valid post ID]


  • August 10, 2017 – Developer notified.
  • August 15, 2017 – Developer responds.
  • August 17, 2017 – Version 4.9.2 released, which fixes vulnerability.