IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Communications Remarks
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S 5.73 Secure operation of a fax server
Initiation responsibility: Head of IT Section, IT Security Management
Implementation responsibility: Administrator, fax mail centre
Secure operation of a fax server requires that communication is secure both
locally and also over the public switched network. The fax server accepts
incoming fax transmissions from other fax servers or fax machines and if the
automatic fax routing function has been activated, it then routes them to the
connected users. Outgoing fax transmissions sent by the connected users are
passed to the fax server and then sent on to recipients. The fax server must
also ensure that local fax transmissions, i.e. fax transmissions from one
workstation to another within the same organisation (or organisational unit)
are sent on internally and not over the public network.
If the fax server is to be operated securely, then, once purchased and installed,
the configuration of its operating system and the fax server application must
be tested thoroughly. If any error messages are generated, the configuration
settings should be altered where this is possible. The test phase should be
followed by a pilot run. Only once the fax server has been demonstrated to be
running without errors in this phase also should it be cleared for actual
operation. The configuration parameters should be documented meticulously,
as should all changes to the configuration settings.
Fax servers store all incoming and outgoing fax transmissions. The length of
time for which these are stored depends on the facilities provided by the fax
server application and the configuration. Thus, for example, it is possible that
outgoing fax transmissions are only held temporarily until a given fax job has
been completed and are then deleted. Again, it could be that incoming fax
transmissions are only stored temporarily until they have been re-routed to
recipients, following which they are deleted. However, another possibility is
that all incoming and outgoing fax transmissions are held on the fax server
until they are specifically deleted by the users concerned or by the fax mail
centre or Administrator. On some fax servers it is also possible to have the
data automatically deleted after a defined period of time. Thus, for example,
all fax transmissions more than three months old are automatically deleted.
Depending on the concept of use, procedures must be defined for the deletion
of fax data on the fax server. At the same time, a procedure should be laid
down as to where and to what extent archiving of fax data should be
performed. As a general rule, fax data should not remain on the fax server any
longer than is absolutely necessary.
Steps must be taken to ensure that unauthorised persons cannot access fax
transmissions. As a first step, the fax server must be physically protected
against unauthorised access. This can only be achieved if the server is located
in a secure server room or server cabinet (see Section 4.3.2 Server room and
Section 4.4 Protective cabinets).
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IT-Baseline Protection Manual: Oktober 2000
Test and documentation
of configuration
Deletion of fax data
Secure siting of the fax
server