Hackers can also steal your data by disconnecting the network cable.

Once a computer is infected with viruses or Trojans, most people first think of "disconnecting the network cable first" to avoid the theft of confidential data through the Internet channel. However, according to research by security experts, even if the network cable is disconnected from the "PC Island", hackers can also use electromagnetic waves and other technologies to steal data.

Ben-Gurion University security researchers in Israel have studied and implemented the use of FMFM radio waves to steal computer data. They successfully used computer monitors as egress channels for transmitting stolen data, while mobile phones with FM reception functions act as receivers.

In their experiments, the researchers implanted airhopper, a hacker program that records the user's keyboard hitting history, on a computer without any network connections. This program can use computer monitors to send FMFM waves, and the stolen data will be transmitted in FM wave mode.

According to reports, on a smart phone with the ability to receive and process frequency modulation waves, researchers have reproduced the history of computer users' keyboard hitting in real time.

It is reported that FMFM wave is used as a means of information transmission to steal data, which is not the first time in history. In the past, hackers used speakers connected to computers as devices for output signals. The researchers used computer displays as a means of signal output, which is more concealed.

However, it should be pointed out that there is a limit on the distance between the receiver and the computer due to the FMFM wave on the display screen, and the distance between the receiver and the computer cannot exceed seven meters. In addition, the data theft rate is very slow, only several bytes of information can be transmitted per second, but this is enough to transmit the password or key text information.

According to reports, researchers at Ben-Gurion University have produced a video to reproduce the process of stealing data using FM waves. They have also written a detailed paper, describe related technical principles. This paper will be published at the security industry conference malcon2014 held this week.

According to the US technology news website "addiction technology" reported at the end of last year, a German Fraunhofer Communication Research Institute expert once developed a malicious attack program for concept verification, multiple malware 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 LAN, communication only requires a distance of no more than 20 meters.

Hackers can also steal your data by disconnecting the network cable.