IT Baseline Protection Manual - The Information Warfare Site

Threats Catalogue Deliberate Acts Remarks
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T 5.99 Analysis of call data relating to the use of
mobile phones
With mobile communications, the signals transmitted on the radio link are not
physically shielded against unauthorised passive monitoring and recording.
Thus an aggressor could perpetrate an attack without the access problem
which occurs on line-connected communications. A second problem which
generally occurs with most radio communication services arises from the fact
that for technical reasons the mobile communication partners have to be
located in order to be contactable. Again, if these partners establish a
connection themselves, they also give away information about their location
through the act of establishing a connection. This location information could
be used by the network or service provider - and also by third parties - to build
up movement profiles.
If an aggressor is familiar with particular filter characteristics over a mobile
phone, he could (although it would be technically effort-intensive) identify
individual phone calls by means of these characteristics. These or other attacks
require that the customer number (IMSI), mobile transceiver number (IMEI)
and subscriber call number (MSISDN) are known.
An insider who, for example, had access to the corporate or private telephone
directories in a company would be able to identify the MSISDN call number.
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IT-Baseline Protection Manual: Oktober 2000