Vuln!! Path it now!!

Hello,
a friend wrote me recently that his wordpress security plugin send him a strange mail. He keeps his wordpress generally updated.

From Sucuri Plugin:

====================================
Subject: Post Update

Login Info:
Time: 20. März, 2019 1:19 pm

Website Info:
Site:
IP Address:

Notification:
Post was updated; identifier: 1195; name: Vuln!! Path it now!!
====================================

So he asked me if I knew something about that. When I search the web, I only find infected websites with the same ‘post update’. No information about the problem.

He installed a backup. His site is and was updated.

Can someone point me to more information about that problem? I would like to prevent that something like that happens to my blog.

Thanks
Daniel