93 lines
4.1 KiB
Plaintext
93 lines
4.1 KiB
Plaintext
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this file was taken from USENET group misc.security
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everything you wanted to know about infinity transmitters
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Date: Wed, 25 Nov 87 13:09:33 EST
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>From: Dave Kucharczyk <ssr@tumtum.cs.umd.edu>
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Subject: Re: Infinity
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Yes, infinity transmitters do exist. they work on the principle that
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the audio path is made even before a dialed phone starts to ring.
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one sends a tone down the line which tells the infinity transmitter
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to "pick up" the phone before the ringing starts, and can then listen
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to teh location where the bug is planted. however these devices are
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pretty much made obsolete by the fact that any of the ESS switches
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do not open an audio path untill they receive answer supervision
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from the dialed end.
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ssr
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Date: Thu, 26 Nov 87 11:51:35 EST
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>From: Larry Hunter <hunter-larry@YALE.ARPA>
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Subject: Re: Infinity
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Ever heard of an "Infinity Transmitter"?
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Yeah, they are pretty old tech bugging devices. They used to work fine,
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but with the advent of separate signalling and voice circuits in ESS
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(the electronic version of Ma Bell's switching system) they became
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obsolete.
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The idea was that the bug would listen to the phone line for a tone.
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When it heard the tone (or combination of tones -- they were called
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harmonica bugs because people often used harmonica notes to trigger them)
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it would pick up the phone and you could listen to what was going on
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in the room that the phone was in, before the phone rang. The problem
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in ESS is that the caller is not connected to the line when it is
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ringing -- the audio connection is only made when the phone is picked
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up -- so the bug cannot hear the incoming tone. No audio path to
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transmit the tone, no infinity bugs.
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One might imagine more sophisticated versions of the infinity bug; It
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could pick up the line WHENEVER it rings, check for the tone, do the
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infinity bug thing is the tone is present and if the tone weren't present
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it would have to generate its own ringing voltage (for the phone) and
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ringing tone (for the caller) until the line really got picked up. As
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you might imagine, the ESS infinity bug would have to be much more
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complicated (read more expensive and more likely to be detected) than
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the old style ones. I've never heard of anyone trying this.
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There are lots of telephone exchanges that are not ESS (step and crossbar
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are the two main alternatives) where the simple old infinity bugs still
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work fine. Any exchange where "Custom Calling" (e.g. call forwarding
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or call waiting) is not available is probably not ESS.
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People still sell things like infinity bugs as "home baby sitters" or
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as burgler alarms, but they answer the phone all the time even though
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they only turn the mike on if they receive a tone. These are usueless
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as bugs because no one can make calls TO the target -- the bug always
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answers the phone.
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You can rest easy re: infinity bugs, although you should be aware that
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it is a pretty trivial task to use electronic surveillance these days
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and that a lot of people do it.
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Larry
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Date: Sun, 29 Nov 87 16:27:38 EST
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>From: Mark W. Eichin <eichin@ATHENA.MIT.EDU>
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Subject: Infinity Transmitters
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I saw an article on these once (on a bboard that got closed down about
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a year later for phone credit card postings). The main idea was that
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someone who wanted to tap the room would add this little circuit board
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to the phone, which would detect some sort of tone on the line when
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the phone first rang, inhibit the ring, and open the microphone.
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Something was mentioned about ultrasound (unlikely, given the quality
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of the phone lines, but it was being vague), and how you
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could tap in from anywhere as long as you could dial direct (ie. even
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from England). The main flaw was that the phone was of course busy (to
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the outside world) the whole time you were monitoring. It was
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allegedly used extensively by PI's to gather ``evidence'' for divorce
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proceedings.
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The article did not have much in the way of technical detail;
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oh well.
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Mark Eichin
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<eichin@athena.mit.edu>
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-------
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DOWNLOADED FROM P-80 SYSTEMS......
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