A virus in space

So the International Space Station got a virus (actually technically a worm). And according to NASA spokesman Kelly Humphries not for the first time.

This time a few on-board laptops on board the ISS where infected with a worm that steals credentials for online games. Apparently no harm done since these machines are not directly online - but this makes the fact even more troublesome how they got infected in the first place. The best guess would be USB thumb drives or copied CD's which all may not have been scanned before being taken by the Astronauts.
Anyone care to give NASA, it's Russian (RKA) and European (ESA) counterparts a free copy of a current Anti-Virus software since they seem to be using Windows and most of the laptops used do may not be equipped with AV software?

What I personally found interesting is the type of malware: A worm specialized on getting gamer account information - could any of the Astronauts have been bored on board and brought a game or two into space? Not that there is anything wrong with this - after all people like Sergei Krikalev spent more time in space than a lot of us in colleague classes...And who would not love to play a round of Space Invaders on the ISS (forget about any current generation consoles - the ISS would probably not be able to meet the power demand of a PS3 or a Xbox360).