A Faraday cage is a metal cage or enclosure that distributes an applied electrical charge evenly across its surface, protecting anything inside from exposure to electromagnetic fields or electrical charge. Invented in 1836 by Michael Faraday but previewed decades earlier by Benjamin Franklin in simpler form, Faraday cages hold electrical charge, but when an outside charge is applied, the electric fields cancel each other out. The inside of the cage, room, or enclosure remains free of any charge.
Faraday cages are used for many everyday items, including microwaves, where the cage protects users from many of the damaging electromagnetic fields within the enclosure. Vehicles and airplanes also utilize Faraday technology – if lightning strikes the exterior, the electrical field generated spreads across the surface of the vehicle or plane and the charges cancel each other, protecting passengers inside from being electrocuted.
Some businesses use Faraday cages to protect their computers or servers, attempting to shield data from outside electromagnetic forces. However, this method isn’t foolproof, as researchers from one Israeli university recently revealed. Although Faraday cages protect their interior from electromagnetic fields, ordinary magnetic fields can still pass through them. If sensitive data is being stored inside a large Faraday cage, such as in a data center, electromagnetic fields can’t penetrate the interior, but some magnetic fields can.
The Israeli researchers identified two methods of extracting data stored within a Faraday cage. The ODINI method manipulates the magnetic output of the CPU, where data is being processed, and allows thieves to extract data through a magnetic field. MAGNETO, the second method, uses a smartphone application with a magnetic field feature to extract data. The methods are similar, but MAGNETO requires a thief to be closer to a Faraday cage to steal the data within because they’re using a smartphone app. Researchers warn that those who use Faraday cages to protect sensitive data should be aware of these weaknesses.