We are definitely not safe at nothing.
No sir, we're not safe with the data in our computer if you do not have an Internet connection. There are several methods or systems with which hackers can gather information from the equipment that we have, to the point that we can even suffer a leak even sound emitted thanks to our hard drive.
How is this possible? According to Ars Technica revealed, based on a publication of ArXiv, there DiskFiltration, created in Ben-Gurion of Israel, and basically University is a technique based on the collection of documents through acoustic signals.
In depth, it corresponds to a method in which the movements of the actuator hard disk is manipulated, so that generate sounds that let you transmit relevant information, whether key, sensitive data, among others, which are picked up by a nearby microphone, being in this case (as you can see in the video) on a cell phone.
Although it has a limited field of scope, DiskFiltration can achieve capture this information in a range of two meters and a speed of 180 bits per second, which would allow, for example, stealing a password encryption 4,096 bits in 25 minutes .
However, beyond that with this method is demonstrated that isolates Internet equipment can be completely violated, all is not so simple. It happens that DiskFiltration to work, the system must be infected with malware, which involves a more "silent" work, in the sense that you must carry an installation process of this malicious software without arousing suspicion.
In addition, this method would work efficiently in an environment in which only noise is the hard disk that is being received by the microphone, so being exposed to any other sound that ultimately end up sabotaging the operation. In addition, the system does not work with SSDs.
However, it is surprising that as advance security systems, are also developing more striking to penetrate these barriers techniques.