There's a common misconception that you need to be connected to the internet to get infected with malware. Well, that's not true and, according to renowned cybersecurity expert Eugene Kaspersky, the folks at a nuclear power plant in Russia learned this the hard way.
Kaspersky recently told the Canberra Press Club in Australia that a Russian nuclear plant was infected by the infamous Stuxnet virus through a tainted USB stick. The plant was connected to the internet at the time, just as the Natanz nuclear facility in Iran which was crippled by Stuxnet in 2010 was not connected. Kaspersky said that the infection occured "during Stuxnet time" but didn't elaborate on the effect of the virus on the Russian nuclear plant. Kaspersky also mentioned that even the International Space Station is infected with malware "from time to time" thanks to USB sticks brought up by scientists.