A covert listening device
, more commonly known as a bug
, is usually a combination of a miniature radio transmitter
with a microphone
. The use of bugs, called bugging
, is a common technique in espionage
and in police
Bug with transmitter
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 or keyboard.
Bugs come in all shapes and sizes. The original purpose of bugs was to relay sound, but today the miniaturization 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.
In 2003 the FBI obtained a court order to surreptitiously listen in on conversations in a car, through the car's built-in emergency and tracking security system. A panel of the 9th Circuit Court of Appeals prohibited the use of this technique because it involved deactivating the device's security features.
Remotely activated mobile phone microphones
Some mobile phone
(cell phone) microphones can be activated remotely, without any need for physical access, even when the phone is switched off. This roving bug feature is reportedly being used by law enforcement agencies and intelligence services to listen in on nearby conversations. A United States court ruled in 1986 that a similar technique, used by the FBI
against reputed former Gulfport Mississippi mobster type cocaine dealers "Bennett Branch" and "Don Tomlinson" dealing cocaine directly under the authority of mob boss David "The Eagle" Easterling after having obtained a court order, was permissible. While it is not possible to do this with every
mobile phone as of 2006, some models are susceptible to being remotely reprogrammed (over the air using methods meant for delivering upgrades (Firmware updates and maintenance) with this capability without the knowledge of its owner. Examples for such mobile phones are Motorola Razr and Samsung 900 series mobile phones.
For the mobile phone as eavesdropping tool the OTA update function is not used to transfer firmware or other official software but rather "special" software which can offer one of the following features:
- The standard software user interface is manipulated or overwritten in a way that phone calls which are done over the infiltrated program are not shown.
- This special software is able to accept an incoming connection (e.g. a call from a certain number) without showing this on the mobile phones user interface. This is possible as long as no connection is existing at the same time.
- If the phone gets switched off the software only pretends this (e.g. turning off the display). Incoming or outgoing connections are still possible.
- Even though the mobile phone gets switched off it is in a standby comparable status. The "special" software is operating in the background like the alarm clock function. Connection establishment or answering a call in this status is already possible.
For all mentioned points not only connection establishment of the telephone lines needs to be considered. Also multi media functions like bluetooth can be used for data transfer.
The person carrying the phone will not know that the phone is transmitting his conversation, but an observant owner may notice that the battery is being depleted sooner than expected.
Instead of transmitting a conversation, bugs can instead record conversations.
Somebody can secretly record his conversation, or nearby conversation, carrying a microphone and recorder. The microphone and recorder can also be placed (mobile in an object or fixed), and later either the whole set or just the recording carrier is recovered.
- 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 even mobiles 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.
Listening from a distance without radio transmission
- 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. However, the simple countermeasure of closing the curtains in a room radically reduces the effectiveness of this surveillance method, assuming of course that the laser beam originates from a source external to the building.
- Some equipment may exhibit microphonics and can therefore, unsuspected by the party listened to, act as a microphone.
- The adversary can use a trojan horse to acquire access to microphones connected to a computer.
- Telephone lines can be used as the transmission medium for devices called "infinity transmitters" or "harmonica bugs". These are covert listening devices connected either inside a target's telephone or somewhere along the telephone line and activated by calling the number. The circuitry silences the ringer long enough for the eavesdropper to send a control tone that activates the microphone. This allows surveillance to be conducted from anywhere in the world, hence the name "infinity". With the advent of remotely programmable mobile telephone technology (smartphones, etc.), this technique can be used without having to plant anything. Called "roving bugs", it involves the upload of surveillance software to the target phone.
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.
Bugs that do not emit radio waves are much more difficult to detect.
Examples of use
- Embassies and other diplomatic posts are often the targets of bugging operations.
- The Embassy of Russia in Ottawa was bugged by the Canadian government and MI5 during its construction.
- The Great Seal bug was hidden in a copy of the Great Seal of the United States, presented by the Soviet Union to the United States ambassador in Moscow in 1946 (not discovered until 1952). The bug was unusual in that it had no power source or transmitter, making it much harder to detect — it was a new type of device, called a Passive Resonant Cavity Bug. The cavity had a metallic diaphragm that moved in unison with sound waves from a conversation in the room. When illuminated by a microwave beam from a remote location, the cavity would return a frequency modulated signal.
- The United States Embassy in Moscow was bugged during its construction in the 1970s by Soviet agents posing as laborers. When discovered in the early 1980s, it was found that even the concrete columns were so riddled with bugs that the building eventually had to be torn down and replaced with a new one, built with U.S. materials and labor. For a time, until the new building was completed, embassy workers had to communicate in conference rooms in writing, using children's "Mystic Writing Tablets".
- In 1990, it was reported that the embassy of the People's Republic of China in Canberra, Australia, had been bugged by the Australian Secret Intelligence Service.
- Colin Thatcher, a Canadian politician, was secretly recorded making statements which would later be used to convict him of his wife's murder. The recording device was concealed on a person who Thatcher had previously approached for help in the crime.
- Electronic bugging devices were found in March 2003 at offices used by French and German delegations at the European Union headquarters in Brussels. Devices were also discovered at offices used by other delegations. The discovery of the telephone tapping systems was first reported by Le Figaro newspaper, which blamed the US.
- The car of Thomas Hentschell, who was involved in the Melbourne gangland killings, was bugged by police.
- In 1999, the US expelled a Russian diplomat, accusing him of using a listening device in a top floor conference room of used by diplomats in the United States Department of State headquarters.
- In 2001, the government of the People's Republic of China announced that it had discovered twenty-seven bugs in a Boeing 767 purchased as an official aircraft for President Jiang Zemin.
- In 2003, Pakistani embassy building was found bugged, contractors hired by MI5 planted bugs in the building in 2001.
- In 2004, a bug was found in a meeting room at the United Nations offices in Geneva.