A “Bug” is a device which is placed in an area which then intercepts communications and transmits or conducts them out of that area to a listening post. The eavesdropper can be just a few feet away from the victim, hundreds of feet, or even miles depending on the kind of bug used.
There are five primary categories of “Bugs”: (Acoustic, Ultrasonic, RF, Optical, and Hybrid).
An Acoustic Bug is the placing of a water glass, stethoscope, or rubber tube into an area and directly intercepting the communication with the naked ear (without the use of electronics). This also applies to sections of an area where sound is leaking though soft spots around windows, structural defects, ventilation structures, poorly installed power outlets, and so on.
An Ultrasonic or VLF Bug is a technique use to convert the sound into an audio signal above the range of human hearing, the ultrasonic signal is then intercepted nearby and converted back to audio. In this case audio pressure waves are used instead of creating a radio signal.
An RF (or Radio Frequency) Bug is the most well known type of bugging device. A radio transmitter is placed in an area or in a device. This is your classic martini olive bug and “spy shop” store device. Extremely easy to detect, but cheap, disposable, and difficult to trace back to the person who planted it.
An Optical Bug is a bugging device that converts sound (or data) into an optical pulse or beam of light. It is rarely used, expensive, and easy to detect. A good example of this would be active or passive laser listening devices.
Any of the above techniques and devices can be combined to make a Hybrid eavesdropping device.
Families of Bugs
Free Space Emission:
• Acoustic/Audible Pressure Waves
• Acoustic/Ultrasonic Pressure Waves
• Optical/Invisible Light (UV, etc…)
• Optical/Visible Light
• Optical/Invisible Light (Infrared, etc…)
• RF Transmission (VLF) 3 kHz - 3 MHz
• RF Transmission (HF) 100 kHz - 70 MHz
• RF Transmission (VHF) 30 MHz - 300 MHz
• RF Transmission (UHF) 300 MHz - 1 GHz
• RF Transmission (Microwave Low) 900 MHz - 3 GHz
• RF Transmission (Microwave Mid) 3 GHz - 12.5 GHz
• RF Transmission (Microwave High) 12.5 GHz - 26.5/33/40 GHz
• RF Transmission (Microwave mm) 26.5/33/40 GHz - 325 GHz
• RF Transmission (Microwave mm2) 325 GHz - 1.5 THz
• Free Space - Magnetic
Conducted Emission:
• Audible (Voice Frequency)
• Ultrasonic
• Video
• Current Carrier up to 500 kHz (AC Mains, Phone, CATV, etc)
• Radio Frequency (AC/Mains Devices, waveguide, etc)
• Fiber Optic
• Other