RE:: [NTSEC] - cheap tempest solution (fwd)

[Ray Arachelian <sunder@brainlink.com>]

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---------- Forwarded message ----------
Date: Mon, 24 Nov 1997 20:50:10 -0500
From: "Stout, William" <StoutW@pios.com>
To: "'ntsecurity@iss.net'" <ntsecurity@iss.net>
Subject: RE: OFF-TOPIC RE: [NTSEC] - cheap tempest solution


> ----- Original Message -----
> From:	Tim Lebrun [SMTP:tlebrun@internetmci.com]
> 
> This may be a stupid  question,  but what is tempest monitoring?  And 
> what kind of information can you get from doing  it?

Ooh, ooh, something I was trained in once.

Tempest protection is the ability to prevent undesirable signals from
escaping a computer system.  

In the old days, electro-mechanical teletypes were used by the military.
 Someone discovered that placing a signal analyzer on the power feed
shows what character is represented by each signal spike.  Automating
the translation gives you a mirror output of each message someplace
else.  Electrical filters (not just transformers which can pass these
signals) prevent this.  Present day keyboards and mice also radiate
signals, readable even though the device is within the FCC part 15 class
A or B device signal emanation restrictions.  Both tube-type and LCD
displays are big transmitters, and can be read by receivers connected to
similarly phased displays.  The receivers can be in a nearby building,
van, plane or satellite.  Makes you think twice when typing PGP messages
or 'accidentally' hitting a 'can be used against you' newsgroup.  Search
for 'Van Eck' for more data.  Physical metallic shielding (and thorough
testing) fixes this.  Network wires and equipment are also major radio
transmitters, metallic types are readable from a distance, and of course
networks can be directly tapped, even glass fiber.  (It's been found in
military environments, a simple wire was surreptitiously stretched above
a ceiling, and which would act as a retransmitter.)  All cables are
guilty of transmitting readable signals if not properly shielded and
filtered.  Van Eck/tempest exploiting devices are used in the
military/spy/wire-fraud/'drug war' business and in both government
sponsored and private corporate espionage.

Don't confuse EMP (Electro-Magnetic Pulse) protection with Tempest,
since EMP is a high-energy pulse (such as created by a nuclear burst)
that generates a high-voltage electrical pulse in both plugged in and
off-line electronic equipment, and typically frys all unshielded
electronics.  Same effect as a power surge, but affects all circuits,
even parts sitting on shelves.  HERF guns do the same thing.

Damn.  I'm also guilty of contributing to the noise and 'firewalls-list'
demise of NTsecurity list.

Bill Stout