Eavesdropping and Counter-Measures: Technology and Technique

Technical Surveillance Countermeasures (TSCM) is another name for such defensive tactics. There are a number of methods being used today that can compromise your information. The theft and protection of secrets is a rapidly expanding market.

Realistically, viewing your threat level has to be considered since everyone should expect some sort of impending privacy issue no matter how small. Thanks largely to the Internet you can arm yourself with much of the knowledge and equipment that the so-called experts use. If a respected agent of computer crimes for the Secret Service in NYC had his T-Mobile Sidekick hacked, who knows what else happens out there to others in any business.

Realistically, viewing your threat level has to be considered since everyone should expect some sort of impending privacy issue no matter how small. Thanks largely to the Internet you can arm yourself with much of the knowledge and equipment that the so-called experts use. If a respected agent of computer crimes for the Secret Service in NYC had his T-Mobile Sidekick hacked, who knows what else happens out there to others in any business.

We'll start acoustic ducting evaluation is the inspection of air ducts, baseboard heaters, coffee rooms, lounges, bathrooms or any way the architecture of a building can transfer sound. A simple example is to put your ear to a wall and listen.

Basically anything that requires the use of the naked ear is called an acoustic bug. Softer surfaces can help muffle sounds but there are more efficient means out there. So be aware that the way an office site is designed can act as a conduit for conversations. Also, be aware of any changes can have adverse affects. Simply playing music can do wonders for masking conversations.

Inspection of telephone equipment and wiring is called line analysis. This is trickier than it seems since sometimes a possible weakness has an actual purpose to the telecommunication system. Especially if it requires constant maintenance and software upgrades.

All instruments should be opened and inspected. Ideally they should be compared with a known safe phone or device. If you're not sure, just remove that piece of loose components and wiring and see if the phone still works. The wiring can be modified in a switch within the handset that essentially turns it into a microphone. If you bypass this hook switch, you can listen in from anywhere on the landline. Technical equipment won't be able to detect this. Time Domain Reflectometry is the sending of a pulse down a telephone line. If there is some sort of disruption; a wall outlet or wiretap; a portion of the pulse will be sent back to the device called a Time Domain Reflectometer (TDR). Then the time difference between the reflection and the continuous run is measured. This helps in determining the distance to the anomaly.

For instance, the microphone you use in a voice recorder can be cut in half. Connect the mike head to one set of unused wires anywhere on the phone wire. Then, so long as there are no breaks in the wire, connect the other end to the jack that connects to your recorder. Now place your recorder to be VOX (voice) activated and now you have an extremely reliable bug. By the way, this should be manually inspected for since using a specialized bug detector may see nothing wrong or inconsistent. A bug such as this that connects to a wire is called a direct tap.

The other general type is called an inductive tap. This is when an instrument is outside a wire but can still distinguish what's transacting over a wire. They are harder to detect since they don't draw power from the line such a standard telephone would. These are referred to as snuffle bugs. A simple probe used in hunting wire signals has a speaker, which can display sounds. By accident one day I was working on an apartment intercom system while using a probe. I could hear conversations throughout the building quite clearly just through the intercom boxes mounted on walls from the master unit in the basement.

If you're using wireless headsets or cordless phones, the radio signals can be intercepted. A cordless phone acts like a radio, but depending on the frequency and a few other factors, can make interception extremely difficult. With some manufacturers, you can buy the same model as your neighbors or the office and have it join their phone system. Double check Caller ID boxes to see if they also record numbers dialed besides obviously those being received. If you're using VOIP (Voice Over IP), remember that calls can be recorded in a fashion identical to intercepting data between two computers.

These packets of data can reassemble an audio file. Obviously electronic devices possess semiconductor components such as diodes, resistors and such. The method to hunt for these components is called Non-Linear Junction Detection (NLJD). The NLJD unit emits a radio signal while listening for the return signal from an electronic device. This becomes very useful when a bug is embedded in a picture frame or wall. The eavesdropping device doesn't have to be active for it to be discovered. If a device is active and transmitting wirelessly (or even on a wire), you can detect it with a Radio Frequency Spectrum Analyzer. Depending on the detection device used, you can determine whether voice, data or video is being sent, and possibly listen to the data. Try to use different size antennas or buy one that collapses. Different frequencies can be detected more efficiently by using various sizes. The use of filters with antennas can also help pinpoint devices on specific frequencies.

There is another budding field related to this topic called Protective Intelligence. Currently there are only a few experts who do this kind of work.

A laser or an infrared beam can be used at a considerable distance from a target building. Conversational sounds can vibrate unto solid objects such as windows. The beam's reflection varies in relation to the movement to the window, which is received and converted back into something audible. To mask the sounds, you could attach a vibrating device (basically an altered electric razor) to the window.

Of course if the window is open, then a laser can target another object instead of the window. A beam of light or laser can be directed to go through a window onto a solid object thereby nullifying such defensive measures again. Generally you really can't detect such attacks unless the laser, infrared or light beam is being used that moment. Certain materials can be used to detect IR emissions, as well as the use of passive night vision gear. Certain fabrics or even a curtain may actually show the spot where a beam of light or laser is being focused. Unless the room is dusty or you have an artificial can smoke, you can follow the beam up to a point and guesstimate it's location. One type of optical bug is an infrared transmitter. When placed in the area of interest for transmission of the conversation to an infrared receiver which will then translate the conversation into an audible format.

Many of these same procedures used can be applied to locating hidden cameras. A relatively new device uses a series of lasers to seek out optics. This was originally intended to locate snipers by bodyguards.

I have listed the techniques, counter-measures and then the counter to the counter-measures to prevent any false sense of security. Usually constant vigilance is your best weapon besides knowing what to look for. Even if you find a "bug sweeper" with good credentials, certifications and experience, ask them detailed questions. Not just to test them but also for your own peace-of-mind. This makes our job easier and we appreciate greatly when dealing with knowledgeable customers.

The author Francis Kielb welcomes any input from readers. Especially any stories you may have. If you have any questions, ask and he'll try to respond promptly. He is currently performing these duties for BHE Security Clients.<br />
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