One of the ways we help to improve the security of WordPress plugins, not just for our customers, but for everyone using them, is the proactive monitoring of changes made to plugins in the Plugin Directory to try to catch serious vulnerabilities. That again has lead to us catching a vulnerability of a type that hackers are likely to exploit if they know about it. Since the check used to spot this is also included in our Plugin Security Checker (which is accessible through a WordPress plugin of its own), it is another of reminder of how that can help to indicate which plugins are in greater need of security review (for which we do as part of our main service as well as separately).

In the plugin Advanced Advertising System the value of a cookie, “view_aas_campaigns”, is passed through the unserialize() function in a couple of locations, which could lead to PHP object injection. One of those locations is in the function is_available() in the file /shortcode.php:

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$person = unserialize(stripslashes($_COOKIE['view_aas_campaigns'])); // Check a person from his cookie.

That code will run on pages where the plugin’s zone shortcode is used as long as it has a campaign attached to it.

We notified the developer of the issue a week ago. We haven’t heard back from them and no new version has been released to fix the issue. In line with our disclosure policy, which is based on the need to provide our customers with information on vulnerabilities on a timely basis, we are now disclosing this vulnerability.

Proof of Concept

With our plugin for testing for PHP object injection installed and activated, set the value of the cookie “view_aas_campaigns” to “O:20:”php_object_injection”:0:{}” and then when you visit a page using the plugin’s zone shortcode (with a campaign attached to the zone) the message “PHP object injection has occurred.” will be shown.

Timeline

• July 2, 2018 – Developer notified.

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