Radio used to hack computer screens

When discussing IT security problems, we typically refer to such techniques as hacking, phishing, and other forms of accessing a vulnerable computer through the Internet. We would be remiss, however, if we did not point out that researchers now believe that computers can be accessed via radio. According to Cambridge University researcher Markus Kuhn, it is possible to use a radio antenna and radio receiver to read nearby computer monitors — nearby meaning from a few offfices away. “I was able to eavesdrop certain laptops through three walls,” says Kuhn. “At the CEBIT conference, in 2006, I was able to see the Powerpoint presentation from a stand twenty-five metere away.”

The technique was first observed in 1985, reports New Scientist, when “Wim Van Eck proved it was possible to tune into the radio emissions produced by electromagentic coils in a CRT display and then reconstruct the image.” Soon known as Van Eck Phreaking, “NATO spent a fortune making its systems invulnerable to it.” Of course, very ffew CRTs are being made these days, but Kuhn’s follow-on efforts proved that the approach would work on flat-panel screens as well, although the technical approach is somewhat different. “The aim is to tune into the radio emissions produced by the cables sending a signal to the monitor. The on-screen image is fed through the cable one pixel at a time. Because they come through in order you just have to stack them up.” One thing to keep in mind: attaching pieces of metal, or using metal hinges, can increase a laptop’s vulnerablity.