As Michael says it's a German Publishing company called VDM Verlag publishing.
It's my understanding that this is not a scam and they actually
publish your dissertation in a form of a book. I know one person from
our program that published a dissertation (i.e. the book is on
amazon).
Nevertheless, I can not assure how well known they are in Germany or
somewhere else (it seems that Michael is better informed in that
sense) but I dont see this as a bad option if you want to put your
dissertion in a book.
Best
G