How scary! Hackers can steal your data even if you disconnect the network cable

Once a computer is infected with a virus or Trojan, most people will first think of "disconnecting the network cable first" to prevent confidential data from being stolen through the Internet. However, according to research by security experts, even if the network cable is disconnected, hackers can use electromagnetic waves and other technologies to steal data "across the air".

Security researchers at Israel's Ben-Gurion University have studied and implemented a method of stealing computer data using FM radio waves. They successfully used the computer monitor as an exit channel for the stolen data, and a mobile phone with FM reception function acted as the receiver.

In the researchers' experiment, they pre-implanted a hacker program called AirHopper on a computer that was not connected to any network cable. This program can use the computer monitor to send out FM waves, and the stolen data will be transmitted in the form of FM waves.

On a smartphone with FM wave reception and processing capabilities, the researchers reportedly recreated the history of computer users' keyboard strokes in real time.

It is reported that this is not the first time that FM waves have been used as a means of information transmission to steal data. In the past, the theft method used speakers connected to the computer as a device to output signals, but this time the researchers used the computer display as a signal output method, which is more covert.

However, it should be pointed out that the above-mentioned data theft relying on the FM frequency modulation wave of the display screen has a distance limitation. The distance between the receiver and the computer cannot exceed seven meters. In addition, the data theft rate is very slow, and only a few bytes of information can be transmitted per second, but this is enough to transmit passwords or key text information.

The Ben-Gurion University researchers have reportedly produced a video reproducing their use of FM waves to steal data, and they have also written a detailed paper describing the relevant technical principles, which will be made public at the security industry conference "Malcon2014" held this week.

According to a report by the American technology news website "Enjoyed Technology" at the end of last year, experts from the Fraunhofer Institute for Communications Research in Germany once developed a malicious attack program for proof-of-concept. Multiple malicious programs installed on different computers can use speakers and microphones to "communicate data" with each other. These computers do not need to exist in the same local area network and can communicate with each other only need to be no more than 20 meters apart.