Attacks to sw servers like KeRanger against Mac

[Winxp-on-Macos]

Dear All,
KeRanger (Ransomware encrypting user files, possibly whole volumes, fraudulently)
spread over 6500 or more Macs because it managed to manipulate the software distribution server
of Transmission (Bittorrent client). The criminals were able sneak their fraudulent version to download server.

BE SENSITIZED while downloading/updating!

How well are VirtualBox servers protected against attacks of such kind?
It is not OS specific question.