At the time of resolution 3 days ago, multiple persons on this list
resolved it to Strato.de. h613092.serverkompetenz.net (81.169.143.178)
Apparently, it has since moved to China. That's the kind of thing that
happens while you took a long weekend.
Are you in a position to quarantine the German server? Or otherwise
aid in investigating the problem? Such as getting German law
enforcement to confiscate the server as compromised and containing
personal identity theft?