S 2.32 Establishment of a Restricted User Environment

Initiation responsibility: Head of IT Section, IT Security Management

Implementation responsibility: Administrator

Where users only have specific tasks to perform, it often will not be necessary to grant them all the rights associated with their own log-in (possibly even Administrator rights). Examples are certain activities of routine system administration (such as making backups, designating a new user) which are carried out using a menu-driven program, or activities for which the user needs only a single application program. Especial care should be taken where temporary employees are involved, to ensure that they are only allowed to use the services and to access the files which they actually need. When they cease working, their accounts should be deactivated and all other access rights should be revoked (see also S 4.17 Blocking and Deletion of Unnecessary Accounts and Terminals).

For these users, a restricted user environment should be established. This can be achieved, for instance, under UNIX with a restricted shell (rsh) and the restriction of access paths with the UNIX command chroot. For a user needing only one application program, this can be entered as a log-in shell so that it is started directly after he logs on, and he is automatically logged off on exiting the program.

The available range of functions of the IT system may be restricted for individual users or user groups. Use of editors or compilers should be prevented unless the user actually needs these to perform his tasks. This can be achieved on stand-alone systems by the removal of such programs and, on networked systems, by the allocation of rights.

Additional controls:

• What user environment and what start-up procedure have been defined for the respective users?

• Are there any procedures regarding user environments in which temporary staff are employed?