Not to make you paranoid or anything, but here’s a security update: researchers have shown that the sounds made by a PC’s cooling fan can be analyzed and interpreted to extract pretty much anything – from passwords to encryption keys.
How is this possible, you ask? With a fan-exploiting malware called “Fansmitter”. Basically, your computer would have to be infected with a malware designed to steal information through interpreting sounds of your computer’s cooling fan. Once it’s installed, the fan-exploiting malware flips the fan speed between 1,000 RPM and 1,600 RPM, which is an audible difference that a microphone, such as one found on any smartphone, can easily pick up on.
In the research, the computer infected with Fansmitter was rattling off a long chain of numbers in binary. There was also a nearby phone listening and analyzing – successfully.
What does this mean? For one, a computer with nothing connected to it could still have data stolen with this malware. For another, it doesn’t work without a microphone. Because of this, Fansmitter and similar malware could never target massive number of users, but they could still cause serious damage to individuals (think people in politics, finance, military, etc.)
Chanwoo's Weekly Tech 