electromagnetic emission – what is it and how do we protect ourselves?

TEMPEST and RÖS refers to the electromagnetic emission by electrical components. If this emission is compromised, there is a risk that the information carried by the emission could leak to unauthorized parties. Generally, two different types of Radiation sources are distinguished:

  1. Information Source: The information that the electronic emission carries.
  2. Physical Source: The electrical components that generated the current/emission carrying the information source.

Depending on the type of 1) information source being transmitted and the type of 2) physical source being used, different types of electromagnetic emission are discussed.

Radio Emission has long posed a significant threat to IT security. Historically, only nations had the capability to conduct RÖS surveillance, and national defense-related agencies were the primary targets. As technology has become both cheaper and more accessible, it is now reasonable to assume that even civilian organizations can engage in surveillance, and as a result, civilian targets may also be at risk.

Four Common Examples of ELECTROMAGNETIC Emission

Radio Emission

A particularly insidious form of emission that can occur in any type of device with some form of radio transmitter, such as mobile phones and radio transmitters. What makes radio-emission especially vulnerable is that it can occur unintentionally between installations containing radio transmitters. Therefore, it doesn’t necessarily require an active emission spy trying to reveal secret information. Additionally, the information can be spread over very long distances.

Emission Crosstalk

Emission crosstalk, or electromagnetic crosstalk, is an umbrella term describing when signals are transferred through electromagnetic coupling. Emission crosstalk is, for example, the main reason why emission can occur. The signals transmitted via emission crosstalk are often in a more or less distorted form, but if they carry information, an emissison risk can still arise.

Keystroke EMISSION

Keystroke emission refers to the electromagnetic signals generated when a person types on a keyboard and a electrical circuit is activated, generating a small electromagnetic pulse. These emissions can be intercepted and analyzed by adversaries to reconstruct what was typed, leading to a potential security breach and data leakage.

This pulse can travel through Air (Radiated Emissions) and Cables (Conducted Emissions)

Video EMISSION

Video emission is a type of emission that can occur when information is transferred from a computer to a monitor, for example.

The different Emissions can further be categorized according to two coupling types: conducted propagation and radiated wave propagation. The coupling types describe how the connections can physically occur.

Conducted Propagation

Conducted propagation mainly occurs when the coupling happens through metallic conductors such as:

  • Power and telecommunication lines
  • Water pipes
  • Reinforcement bars, etc.

A conducted coupling typically occurs at frequencies < 30 MHz. Such shortwave frequencies (also known as high-frequency wavelengths) can provide audibility over very long distances under favorable conditions.

Radiated Wave Propagation

Radiated wave propagation occurs instead when the coupling happens between two transmitting antennas. Here, the frequency is limited to higher frequencies > 30 MHz. Radiated wave propagation can, for example, occur during electromagnetic crosstalk (which can create radio-emission) where electromagnetic coupling arises between two transmitters.

How Can We Protect Ourselves?

There are several ways to protect against radio emission. Briefly, the different protection mechanisms against emission can be categorized, read more below.

Emission-protected equipment

With specially emission-protected equipment from Fibersystem you can either eliminate or limit the risk of emission. At Fibersystem, we offer emission protected equipment for all needs from TEMPEST Level C (RÖS U3) up to TEMPEST Level A (RÖS U1).

Emission-protected rooms/cabinets

If equipment carrying sensitive information has not been equipped with its own emission protection, it can instead be placed in a specially emission-protected room or cabinet. Such a emission protected room contains walls that prevent electromagnetic signals from reaching the outside world. Just like emission-protected equipment, there are different levels of this protection, where shell protection TEMPEST Level A and RÖS U1 means elimination of emission risk and shell protection TEMPEST Level B (RÖS U2) and TEMPEST Level C (RÖS U2) means limitation of emission risk. Fibersystem has cabinets with shell protection in all TEMPEST and RÖS standards.

Emission safety distance

Emission safety distance means taking advantage of the fact that the strength of radio frequency signals decreases with increasing distance. By utilizing natural protections in the environment, the emission risk can also be reduced. Some simple measures to reduce the risk of emission include:

  • Placing sensitive equipment in the innermost part of the building.
  • Placing sensitive equipment as close to the ground as possible – preferably below ground.
  • Placing sensitive equipment close to surrounding walls.
  • Never place equipment carrying sensitive information directly in front of a window where there is a clear line of sight for eavesdropping equipment.

Fibersystem can provide emission shielded products to protect your sensitive data.