Emanation Security

Another method that attackers use to steal information is to intercept electrical
signals that radiate out of computers and devices. Every electrical device emits
some amount of electrical signals or radiation, which attackers can intercept using
specialized equipment. These signals can carry sensitive information.With the right
hardware and software, the attackers can reconstruct this data without the individuals
using the devices ever knowing about it.
We see these types of activities in spy movies where there is a white van in
the parking lot of a building, trying to pass itself off as a utility vehicle. But the
van is actually filled with specialized equipment and highly skilled individuals
with the goal of gaining access to information that they are not supposed to be
able to access. This may seemas though it only exists in spy novels and movies,
but there are actually countermeasures that are often used to protect against
these types of attacks. The three main countermeasures to emanation attacks
are TEMPEST, white noise, and control zones.
TEMPEST was a study of monitoring these signals and preventing others
frombeing able to monitor specific devices. TEMPEST then graduated into being
a standard that vendorsmust meet if they want their products to be considered
TEMPEST protection mechanisms. The devices have a special shielding,
referred to as a faraday cage that allows only an acceptable amount of radiation
to escape. Typically, only highly secure organizations implement TEMPEST
products because it is expensive, and the buying and selling of TEMPEST devices
is highly controlled by the government.
White noise is another countermeasure that can be used to fight emanation
attacks. In this case, a uniform spectrum of random electrical signals is purposely
emitted to jam the signals that are released from an environment.White
noise makes it difficult for an attacker to decipher real electrical signals that
could be deemed beneficial.
Finally, control zones can be used within buildings to block the electrical signals
as they leave a facility or room, as shown in Figure 2-9.Walls, ceilings, and
floors can be constructed with materials that greatly reduce the amount of signals
that are released from that area.