What is electromagnetic wiretapping TEMPEST? Explanation of mechanisms and countermeasures from the perspective of information security

Explanation of IT Terms

What is TEMPEST?

TEMPEST, also known as electromagnetic wiretapping, is a method of eavesdropping on electronic communication by capturing the unintentional electromagnetic radiation emitted by electronic devices. These devices can include computers, telephones, fax machines, or any other electronic equipment that emits electromagnetic signals during their normal operation.

Mechanisms of TEMPEST

TEMPEST attacks exploit the fact that electronic devices generate electromagnetic signals that can leak outside of their intended recipients. By using specialized equipment and techniques, an attacker can intercept and analyze these electromagnetic emissions to gather sensitive information.

There are three main mechanisms that allow TEMPEST attacks to occur:

1. Electromagnetic emanations: When electronic devices are powered on and processing data, they emit electromagnetic signals that can be captured using specialized antennas and receivers. These signals contain information about the operations of the device, including the data being processed or displayed.

2. Power line emissions: Electronic devices are connected to power lines, which can act as antennas, unintentionally radiating electromagnetic signals. By analyzing these signals, an attacker can gather information about the device’s activities.

3. Van Eck phreaking: This technique involves eavesdropping on the electromagnetic radiation emitted by a display device, such as a computer monitor, to reconstruct the information being displayed. Van Eck phreaking can be done even without physically accessing the targeted device.

Countermeasures against TEMPEST

Protecting against TEMPEST attacks requires adopting various countermeasures to reduce or eliminate the unintentional electromagnetic radiation emitted by electronic devices. Here are a few countermeasures commonly employed:

1. Shielding: Shielding involves adding physical barriers or enclosures around sensitive electronic equipment to prevent the leakage of electromagnetic radiation. This can be done by using special shielding materials, conductive coatings, or Faraday cages.

2. Filtering: Installing filters on power lines can help suppress the power line emissions that can be intercepted by attackers. These filters can reduce the amount of electromagnetic radiation that leaks through the power supply.

3. Reducing emissions: Reducing the unintentional electromagnetic emissions from electronic devices can be achieved by utilizing techniques such as signal attenuation, using low-emission components, or redesigning circuit configurations.

4. Device placement: Properly positioning electronic devices within an environment can minimize the risk of eavesdropping. Placing devices away from external walls or using strategic layouts can help attenuate the signals that might be intercepted.


TEMPEST, or electromagnetic wiretapping, is a technique used to intercept electronic communication by capturing unintentional electromagnetic radiation. Understanding the mechanisms of TEMPEST attacks and employing countermeasures is crucial for maintaining information security. By implementing measures such as shielding, filtering, and reducing emissions, organizations can significantly reduce the risk of falling victim to TEMPEST attacks.

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