Surprisingly, this apparently isn't the first time this has happened to NASA. They haven't, to this point, been using antivirus software on the laptops astronauts take into space with them.
A lesson for us all? Yep.
However, the virus wasn't something that would bring the ISS crashing to Earth. The W32.Gammima.AG
worm is pretty old: discovered last August. Since it targets passwords to various online games, and the lag from the ISS would be pretty bad, it's safe to say that the astronauts weren't doing anything that the virus would find inviting.
NASA believes the virus may have infected the laptops via a flash drive one of the astronauts used. This certainly makes sense, as the virus propagates by using removable media, according to Symantec.
They plan to put some security measures in place for the future. Makes sense, particularly now that this has been publicized. Can you imagine a hacker really trying to bring down a space station. Nah, not likely, but it could compromise the ability of the astronauts to play Diablo 3 via their LAN in the future.