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Covert listening
device
From
Wikipedia
A 'bug' is the common name for a covert listening
device, usually a combination of a miniature radio transmitter
with a microphone. The use of bugs, called bugging, is a
common technique in espionage and, increasingly, in police
investigations.
Most bugs use a radio transmitter, but there are many other
options for carrying a signal: radio frequencies may be
sent through the main wiring of a building and picked up
outside; transmissions from a cordless phone can be monitored;
and it is possible to pick up the data from poorly configured
wireless computer networks or tune in to the radio emissions
of a computer monitor.
Bugs come in all shapes and sizes. The original purpose
of bugs was to relay sound, but today the miniaturisation
of electronics has progressed so far that even commercially-available
bugs designed to carry TV signals are usually the size of
a cigarette packet. Professional bugs can fit into pens,
calculators and other commonplace items. Some are only the
size of small shirt buttons, although the power and operational
life of the smallest bugs is very short.
The development of modern 'wireless' technology has presented
new security concerns. To be 'wireless' a device must transmit
information, either by radio waves or infrared light, and
this potentially makes all the information sent via that
link available to others. Radio waves are the easiest to
intercept, but even infrared transmissions can be picked
up through a window. Some wireless devices, such as wireless
computer networks, do encrypt transmissions, but the standard
forms of encryption are weak. Such devices, whether wireless
keyboards or wireless telephones, should not be used in
any environment where sensitive information is handled.
Most bugs emit radio waves. The standard counter-measure
for bugs is therefore to 'sweep' for them with a receiver,
looking for the radio emissions. Professional sweeping devices
are very expensive. Low-tech sweeping devices are available
through amateur electrical magazines, or they may be built
from circuit designs on the Internet. But sweeping is not
foolproof. Advanced bugs can be remotely operated to switch
on and off, and some even rapidly switch frequencies according
to a predetermined pattern in order to make location with
sweepers more difficult. A bug that has run out of power
may not show up during a sweep, which means that the sweeper
will not be alerted to the surveillance.
Those bugs that do not emit radio waves are very difficult
to detect. Radio-based bugs are a technical solution to
a problem - remotely listening to people's conversations
- but a simpler option is simply to record the conversation
on a normal recording machine. There are a number of options
for this:
Pocket sized devices, either worn or carried in baggage,
linked to a small microphone which is usually mounted on
the surface to pick up the audio. Digital devices such as
minidisc recorders or the latest palm-sized camcorders produce
very high quality recordings and are conveniently small.
Larger recording devices hidden in the room, for example
above suspended ceilings. These are popular in workplaces
for monitoring staff.
Ultra-directional microphones, or parabolic microphones.
These are like the microphones seen on camcorders, or carried
by sound technicians. They are constructed to receive signals
only from one direction. The most high-tech directional
microphones can eavesdrop on conversations from a hundred
metres away or more. Microphone arrays can be used as well.
Laser microphones. These are very expensive and highly technical
to operate. A laser beam is bounced off a window, or off
any object near to the conversation monitored. Any object
which can resonate/vibrate (for example, a picture on a
wall) will do so in response to the pressure waves created
by noises present in a room. The electronics detect the
minute difference in the distance travelled by the light
to pick up this resonance and reproduce the sound causing
it.
Some equipment that is not a threat on itself may exhibit
microphonics.
Mobile phones can be used as bugs as well.
The adversary can use a trojan horse to acquire access to
microphones connected to computers.
If a microphone is hidden in a room it is almost impossible
to detect, as it has no radio emission. Very sensitive equipment
could be used to look for magnetic fields, or for the characteristic
electrical 'noise' emitted by the computerised technology
in digital tape recorders; however, if the place being monitored
has many computers, photocopiers or other pieces of electrical
equipment installed, it may become very difficult. Older
analog equipment is even more difficult to detect.
Another method is using very sensitive infrared cameras
to detect waste heat of a bug, or different thermal conductivity
of a place where it is hidden after briefly chilling the
surface of the object with eg. liquid nitrogen. -H
If you need a profeesional to sweep your office or home
please call (714) 773-5345 or (877) 832-2388.
We at Hodson and Associates are Licensed Private Investigators
and can help you with a TSCM. Please call today. |
