IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Hardware & Software Remarks
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S 4.71 Restrictive utilisation of database links
Initiation responsibility: Head of IT Section, IT Security Management
Implementation responsibility: Administrators
Database links allow a database to access the information in another database.
To ensure adequate protection of such information however, database links
should only be used when absolutely necessary.
To allow access control of users employing database links, a suitable concept
of defining user IDs is necessary. In principle, a user is able to access an
extraneous database if it recognises the ID with which the user logs into the
local database. Additional security is provided by the possibility of
establishing links with an explicit specification of the user ID and a password.
In principle, every database user is entitled to establish database links
(provided that the user is able to execute the related CREATE command). In
general however, only the administrator should be authorised to establish such
links. This applies especially to database links which can be employed by all
users (PUBLIC DB-Links). The right to establish database links should
explicitly not be granted to standard user IDs.
Furthermore, the number of database links which can be employed
simultaneously by a user must be restricted in order to control the loads on the
database servers. Otherwise an intruder could exploit this situation to obstruct,
or even completely paralyse, the operation of the database servers.
Documentation of the database links configured by the administrator is
indispensable. In addition to the types of link (established via a special user
ID, or given that the locally applicable database ID has also been configured,
for the connected database) the documentation should also list the user groups
authorised to make use of each database link. As already mentioned, database
links defined as PUBLIC can be used by all database IDs.
Additional controls:
- Does a concept for defining user IDs exist, and if so, to what extent does it
take the possible use of database links into account?
- Which user IDs are authorised to establish database links?
- Does a concept for employing database links exist, and if so, has it been
implemented?
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IT-Baseline Protection Manual: Oktober 2000