Around 1 week ago a vulnerability was reported in a block of code called PHPMailer which is a component in all WordPress websites. A fix has been published and most sites will have picked it up by now.
I have noted an increased volume in the number of spam messages coming through websites probably because hackers are testing the mail send function to see if they can use it.
Am I affected?
I am currently working through all of the websites, but I may have missed doing this on the first 20 or so because it was not a problem at the time I visited.
Next time you login to your site go to WordFence in the menu and check the report under Scan (scroll down to the bottom). This will tell you the results of the last scan carried out on the website. If you see one relating to PHPMailer as in the case below then you need to take some action.
If you see a list of issues relating to Readme.txt files then do not worry about it.
If you can see this message then go to the Dashboard and updates. Then reload the latest version of WordPress by clicking on the Re-install Now. This will load a fresh copy of the current version of WordPress with the patched code for PHP Mailer.
I suspect this is belt and braces, because technically the site should update itself even for patches when they come out. The problem is WordFence is reporting that the file has been modified from the one in the repository, which is where it is picked up from. I think when an installation is performed a checksum is made on the code, and what is happening is the checksum is being confirmed and coming up with a mismatch because the files in the repository have changed, and hence the warning. By reloading WordPress and then repeating the scan, this proves to resolve the issue.
I have not got Wordfence on my site
If you cannot locate WordFence on your site at the moment, don’t worry about this, I am re-installing it on a lot of sites and removing some other plugins relating to security. I will be visiting your site over the first week in January and checking it. If it is not set up, I will set it up for you.