By adjusting the speed of your computer's processor up or down and encoding fluctuating data, hackers can extract information from software that is prohibited from connecting to the Internet. Details of these variations may be accessible remotely, circumventing the ban.
Some computers handle sensitive tasks and are therefore completely disconnected from the Internet to avoid hacking. This is a precaution known as air gapping. However, attackers are able to successfully install malware on machines such as:
Source: www.newscientist.com