[551] in Best-of-Security
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daemon@ATHENA.MIT.EDU (David M Walker)
Thu Jan 22 20:27:30 1998
Date: Fri, 23 Jan 1998 03:30:02 +1100 (EST)
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From: David M Walker <davidw@datamgmt.com>
X-Originated-From: From: David M Walker <davidw@datamgmt.com>
The following article appeared on 29th December 1997 in the Times
(http://www.sunday-times.co.uk). I am the Technical Architect for
the Swisscom Mobile project and comment below ...
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Mobile phones used as trackers
BY MICHAEL EVANS AND NIGEL HAWKES
MOBILE PHONES can be used as tracking devices to pinpoint users within
a few hundred yards, according to a report yesterday.
Sonntags Zeitung, published in Zurich, said Swiss police had been
secretly tracking mobile phone users through a telephone company
computer.
"Swisscom [the state-owned telephone company] has stored data on the
movements of more than a million mobile phone users and can call up the
location of all its mobile subscribers down to a few hundred metres and
going back at least half a year," the paper reports, adding: "When it
has to, it can exactly reconstruct, down to the minute, who met whom,
where and for how long for a confidential tte--tte."
Swisscom officials confirmed the practice but said information about
mobile phone customers was handed over only on production of a court
order. The newspaper claimed that about 3,000 base stations in
Switzerland tracked the location of mobile phones as soon as they were
switched on.
Renato Walti, an investigating magistrate in Zurich who specialises in
organised crime, told the paper: "This is a very efficient investigation
tool."
Toni Stadelmann, head of Swisscom's mobile phone division, is quoted as
saying: "We release the movement profile of mobile telephone customers
on a judge's order."
In Britain, six mobile phone companies are understood to have
arrangements with law enforcement agencies to provide coding information
on individual phones used by suspected terrorists or serious criminals,
but there are legal and procedural restrictions. As in all intelligence
and police work, according to one intelligence source, technical
surveillance is carried out only for what the source described as
"focused" operations on key individuals.
"Some people might think the law enforcement authorities are tracking
every mobile phone user, but that is complete nonsense. We have to have
our antennae out to get the critical leads, but once we've got a lead
we focus on that individual and a lot of effort goes into filtering out
extraneous information."
Earlier this year there was a row in Australia when police admitted that
they were using the mobile phone network to keep track of known
criminals. Signals emitted by the criminals' phones and picked up by
local base stations were being used to pinpoint people, providing "a
very valuable investigative tool", according to Sergeant Frank Helsen
of the New South Wales Police Service Crime Data Centre.
The method worked even if the phones were not in use, since they emit
signals automatically every half hour. Data collected by the phone
companies whose base stations pick up these calls was being
reconstructed to pinpoint the whereabouts of the phone users.
Chris Puplick, the chairman of the New South Wales Council for Civil
Liberties, protested that walking around with a mobile phone was "like
walking around with a beeper or an implanted transmitter".
In the Australian case, the mobile phone companies said that they did
not routinely keep the data from phones but would do so if a warrant
were issued in advance. The police service declined to say how often
this happened.
In the Swiss case, it appears that the data is automatically recorded.
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It is true that while a call is in progress the person can be tracked with
standard radio tracking techniques. It is also true that Phone Companies
store the Call Data Record (CDR) for billing and marketing purposes. Most
Telcos now try to store 18 months of this data (Swisscom will be about
2Tb of info after 18 months). The CDR contains the base station or cell
that was being used (remember that a user in a car is likely to pass
through many cells. Cells overlap depending on location and may be small
(a square kilometer in a town) or large (fifty square kilometers in open
flat countryside).
But the statement:
"Swisscom [the state-owned telephone company] has stored data on the
movements of more than a million mobile phone users and can call up the
location of all its mobile subscribers down to a few hundred metres and
going back at least half a year," the paper reports, adding: "When it
has to, it can exactly reconstruct, down to the minute, who met whom,
where and for how long for a confidential tte--tte."
is totally implausable, we have enough problems with the volume of CDR
data as it is without storing the radio direction info as well.
It is well known that subscribers may also not be the user, e.g. a man
may be a subscriber twice, but may give one phone to his wife - so who is
using the phone and how do you know that ?
Furthermore Swisscom have a service called 'Natel Easy-Go' where you can
pay cash for a pre-paid mobile phone. Unless the person pays by credit
card to re-charge the prepayment element you don't even know who the
subscriber is !
Finally the Police in most countries do use the CDR information from
Telcos both mobile and fixed line, and in most countries it is controlled
by court order. Even the limited information that I have described as
being available helps catch criminals, who like all of us are creatures
of habit and normally just pick up the nearest phone !
davidw
