After some updates, some plugin has stupid idea to write something on index file (I have ‘Kangaroos cannot jump here’). I suspect how it is GTranslate, as that was only unusual update.
What to do now??? No idea as emails are extremely frequent (2 – 5 min), as well production of index files in Quarantine.
Go to the BPS Pro Quarantine Log page and copy one of Quarantine Log entries for the index file and paste it in your forum reply so I can see what might be going on.
Since the initial incident took extra measures, on the site itself and the host, changed the host password to random generated one, all WordPress logins to random generated 20 character passwords, all FTP passwords etc.