The WordPress plugin File Manager contains a critical vulnerability that is actively being exploited by attackers to compromise WordPress sites. We saw a handful of these incidents on September 1st as the attacks were just starting to ramp up and a few more since then. Fortunately, in these cases the solution has been relatively simple: restore from a prior backup and delete the plugin.

This particular vulnerability has been present in the plugin since version 6.4, which was released in May. It was patched with the release of 6.9 on September 1st.

Due to the rate at which these attackers were occurring, we have proactively identified every single instance of a vulnerable version of this plugin being used on our servers and have removed it. Since this plugin merely offers a file management interface within the WordPress admin section, removing it doesn’t impact the functionality of the website. Users are welcome to re-install the latest version of this plugin if so desired.

This particular incident does bring to light an important topic though. It is best practice to use as a few plugins as possible, those that aren’t needed should be deleted (not just deactivated). There is certainly an argument to be made that a file manager plugin like this should never be installed but even if you disagree with that, there really isn’t strong justification for keeping a plugin like this installed beyond its intended use. It just allows another possible point of entry for attackers to exploit should a vulnerability be found.

Please keep this in mind as you continue to develop and secure your WordPress instances. If we can help in any way, please drop us a ticket and we’ll be happy to do so.