On Sunday we had probing on our website for usage of the plugin WP Security Audit Log, which has 80,000+ installs according to wordpress.org, from what looked to be hackers. Considering that plugin is known to vulnerable we didn’t further check in to what was going on, which was a mistake, but one that other monitoring we do allowed us to rectify today.

As part of our daily monitoring of subversion log messages from the WordPress Plugin Directory for mentions of security fixes, we found that 10 plugins had mentions of security fixes yesterday, which is way out of line with what we normally see and hinted that there might be a common issue between the plugins. As we started trying to figure out what was going on, we noticed that many of them were updating a third-party library Freemius, which is described as  a”[m]onetization, analytics, and marketing automation platform”. In looking in to that we noticed that Freemius was citing WP Security Audit Log as using their library. With one of those plugins, looking at the changes made, we saw the possibility that a major vulnerability had been fixed. Further checking confirmed that an authenticated option update vulnerability was fixed, which would allow anyone with access to a WordPress account to take over a website and is a type of vulnerability hackers have tried to exploit widely in the past so there is likely to be plenty of attempts due to this. [Read more]