Thanks for your support, Redis!
Everything I find points to euw0300066-pip.eu.verio.net as that's the only address gameguard.des seems to connect to. Checked with eXtended Task Manager too. Same result.
Edit:
Turns out it was the right address. There is a major problem tho. GameGuard.des does not connect to euw0300066-pip.eu.verio.net but rather to 213.198.85.7 which is sort of the same but only 'sort of'. Now, it is not possible to edit the hosts file to resolve the hostname as 127.0.0.1 because it connects to the IP directly. I have the full address including paths where GameGuard.des is getting the files but I can't redirect the address to my local webserver. As far as I've read, it's not even possible under windows to do that. Maybe there is a super trick but I don't know it and haven't found it on google. This would be easy on linux tho ...
Anyway, I'm trying to change GameGuard.des on assembler level to write 127.0.0.1 to the (3) memory addresses responsible for the IP. But so far, I have not been very successfull and I'm not entirely sure this works at all. Still good for learning tho ^^
Will keep you guys updated.