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Listening with lasers

You may have seen lasers being used in Hollywood films, but did you know they can be used to conduct an eavesdropping attack in real life?

Laser eavesdropping is a sophisticated technique typically used by individuals from hostile states to covertly gather information. It involves the remote use of an invisible laser to listen into conversations being held inside a target location. It’s an expensive and very technical form of eavesdropping attack, but it’s preferred by some because it can be conducted from a remote location, therefore reducing the chances of being detected.

As technical security specialists, our officers at UK NACE share how the technology works and their expert recommendations to minimise your risk below.

How does it work?

Laser eavesdropping relies on vibrations created by the soundwaves from speech, or sound in general. The sound waves cause hard objects in a room, such as coffee cups or windows to vibrate a tiny amount. When you point a laser at one of these objects, the vibrations from that object cause the laser’s reflected beam to modulate or jump about. This modulated reflected beam is picked up and converted from light back to an audio sound wave. It can then be listened to and recorded.

What does this mean?

Due to the nature of laser eavesdropping, the technique can be used to conduct a standoff attack up to 500 metres away from the target location. There’s no need to enter the target location to install a physical technical surveillance device (TSD), therefore the victims are unlikely to ever know, or be able to prove, such an attack has occurred.

Is this a threat to me?

As a sophisticated eavesdropping technique, everyday members of the public may not be routinely exposed to it. Despite this, it’s not unknown in the world of corporate espionage so you may still be at risk if you work in an office or business.

All information can be of interest to an individual with ulterior motives, irrespective of its sensitivity, so it’s important to carefully consider the locations for sensitive conversations or meetings.


Laser eavesdropping can intercept a conversation in any room with a window, and generally, it’s difficult to completely secure rooms with windows, so having a good security culture can protect you and your organisation.

Our experts in counter-eavesdropping at UK NACE advise taking the following measures to help reduce the risk of a laser eavesdropping attack:

  • Install heavy blinds or curtains over windows which could help prevent a laser beam reaching a target.
  • Make sure, where possible, offices are not overlooked or in the line of sight of other buildings, especially high-rise apartments, which provide threat actors with a platform to conduct a laser attack.
  • Ensure a clear desk policy to reduce the number of objects in a room that would be easy for a laser to pick up sound wave vibrations from.

Further links

  • UK NACE Operations

    We protect against technical espionage and prevent organisations’ information and premises from compromise.