Van Eck phreaking, also known as Van Eck radiation, is a form of network eavesdropping in which special equipment is used for a side-channel attack on the electromagnetic emissions of electronic devices. While electromagnetic emissions are present in keyboards, printers, and other electronic devices, the most notable use of Van Eck phreaking is in reproducing the contents of a cathode-ray tube (CRT) display at a distance.

Information that drives a CRT video display takes the form of electrical signals in the RF range. The electric signal which drives the electron beam is amplified to up to around one hundred volts from TTL circuitry. The signal leaks out from displays and may be captured by an antenna, and once synchronization pulses are recreated and mixed in, an ordinary analog television receiver can display the result. These emissions are correlated to the video image being displayed, allowing an attacker to remotely recover the image.

While the phenomenon had been known by the United States Government and Bell Labs as early as the Second World War, the process received its name after Wim van Eck published the first unclassified technical analysis of the security risks of emanations from computer monitors in 1985. While phreaking is the process of exploiting telephone networks, the term is used here because of its connection to eavesdropping.

History

Government researchers were already aware of the danger, as Bell Labs had noted this vulnerability to secure teleprinter communications during World War II and was able to produce 75% of the plaintext being processed in a secure facility from a distance of 80 feet (24 metres).

  • Van Eck phreaking Demonstration
  • Tempest for Eliza is a program that uses a computer monitor to send out AM radio signals, making it possible to hear computer-generated music in a radio.
  • Video eavesdropping demo at CeBIT 2006 by a Cambridge University security researcher
  • eckbox – unsuccessful or abandoned attempt in spring 2004 to build an open-source Van Eck phreaking implementation
  • Sniffing wireless keyboard link
  • system-bus-radio – an implementation of Van Eck phreaking using certain processor instructions on a general purpose computer