One way to protect computer networks from malicious attack is to disconnect them from the internet. This approach, known as air-gapping, creates a physical barrier between the network and the nasty world of malicious attackers beyond.
But air-gapped computers are not perfectly secure. Hackers have developed various ways of infecting them using portable devices such as USB drives. The famous 2010 Stuxnet attack used this method of infection to inject malware capable of disabling centrifuge equipment in the Iranian nuclear program.
