How to Tell If Your Cell Phone is Bugged

Greetings.  A story is making the rounds right now regarding
FBI use of cell phones as remote bugs
(e.g. http://news.com.com/2100-1029-6140191.html ).  I originally
wrote about this concept in my PRIVACY Forum in 1999 ("Cell Phones
Become Instant Bugs!" - http://www.vortex.com/privacy/priv.08.11 )
so the issue is real, but we still need to bring the current saga
back down to earth. 

This discussion doesn't only relate to "legal" bugs but also to the
use of such techniques by illegal clandestine operations, and
applies to physically unmodified cell phones (not phones that might
have had separate, specialized bugs physically installed within
them by third parties).

There is no magic in cell phones.  From a transmitting standpoint,
they are either on or off.  It is true that many phones have an
alarm feature that permits them to "wake up" from their usual "off"
state.  However, this is not a universal functionality, even in
advanced phones such as PDA cell phones, which now often have a
"totally off" mode available as well.

It is also true that some phones can be remotely programmed by the
carrier to mask or otherwise change their display and other behaviors
in ways that could be used to fool the unwary user.  However, this
level of remote programmability is another feature that is not
universal, though most modern cell phones can be easily programmed
with the correct tools if you have physical access to the phones,
even briefly.

But remember -- no magic!  When cell phones are transmitting -- even
as bugs -- certain things are going to happen every time that the
alert phone user can often notice. 

First, when the phone is operating as a bug, regular calls can't be
taking place in almost all cases.  A well designed bug program could
try to minimize the obviousness of this by quickly dropping the bug
call if the phone owner tried to make an outgoing call, or drop the
bug connection if an incoming call tried to ring through.  But if
the bug is up and running, that's the only transmission path that is
available on the phone at that time for the vast majority of
currently deployed phones.  Some very new "3G" phones technically
have the capability of running a separate data channel -- in which
voice over IP data could be simultaneously transmitted along with
the primary call.  But this is pretty bleeding-edge stuff for now,
and not an issue for the vast majority of current phones. 

Of course, if a cell phone is being used as a remote bug, the odds
are that the routine conversations through that phone are also being
monitored, right?  So this "one call at a time" aspect isn't as much
of a limitation to bugging as might otherwise be expected.

Want to make sure that your phone is really off?  Taking out the
battery is a really good bet.  Don't worry about the stories of
hidden batteries that supposedly can be activated remotely or with
special codes.  The concept makes no sense in general, and there
just isn't room in modern cell phones for additional batteries that
could supply more than a tiny bit of added power, if any.

But if your battery seems to be running out of juice far too early
(despite what the battery status display might claim), that might be
an indication that your phone is being used to transmit behind your
back (or it might be a worn out battery and a typically inaccurate
battery status display).

Another clue that a phone may have been transmitting without your
permission is if it seems unexpectedly warm.  You've probably
noticed how most cell phones heat up, especially on longer calls.
This is normal, but if you haven't been on any calls for a while and
your cell phone is warm as if long calls were in progress, you have
another red flag indication of something odd perhaps going on.

Finally, if you use a GSM phone (like the vast majority of phones
around the world, including Cingular and T-Mobile in the U.S.)  you
have another virtually fullproof way to know if you phone is
secretly transmitting.  You've probably noticed the "buzzing"
interference that these phones tend to make in nearby speakers when
calls or data transmissions are in progress.  A certain amount of
periodic routine communications between cell phones and the networks
will occur while the phones are powered on -- even when calls are not
in progress -- so short bursts of buzzing between calls (and when
turning the phones on or off) are normal.

But if you're not on a call, and you hear a continuing rapid
buzz-buzz-buzz in nearby speakers that lasts more than a few seconds
and gets louder as you approach with your phone, well, the odds are
that your phone is busily transmitting, and bugging is a definite
possibility.  Note that this particular test is much less reliable
with non-GSM phones that use CDMA (e.g. Sprint/Verizon phones),
since CDMA's technology is less prone to producing easily audible
local interference.  This strongly suggests that CDMA phones may be
preferred for such bugging operations.

The odds of most people being targeted for bugging are quite small.
But it's always better to know the technical realities.  Don't be
paranoid, but be careful.

--Lauren--
Lauren Weinstein
lau..._at_vortex.com or lau..._at_pfir.org
Tel: +1 (818) 225-2800
http://www.pfir.org/lauren
Co-Founder, PFIR
   - People For Internet Responsibility - http://www.pfir.org
Co-Founder, IOIC
   - International Open Internet Coalition - http://www.ioic.net
Founder, CIFIP
   - California Initiative For Internet Privacy - http://www.cifip.org
Moderator, PRIVACY Forum - http://www.vortex.com
Member, ACM Committee on Computers and Public Policy
Lauren's Blog: http://lauren.vortex.com
DayThink: http://daythink.vortex.com

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