IBM z/OS UNIX groups must be defined with a unique GID.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-223857	RACF-US-000200	SV-223857r868907_rule		Medium

Description
To assure accountability and prevent unauthenticated access, organizational users must be identified and authenticated to prevent potential misuse and compromise of the system. RACF userid groups, and started tasks that use z/OS UNIX facilities are defined to an ACP with attributes including UID and GID. If these attributes are not correctly defined, data access or command privilege controls could be compromised.

Description

To assure accountability and prevent unauthenticated access, organizational users must be identified and authenticated to prevent potential misuse and compromise of the system. RACF userid groups, and started tasks that use z/OS UNIX facilities are defined to an ACP with attributes including UID and GID. If these attributes are not correctly defined, data access or command privilege controls could be compromised.

STIG	Date
IBM z/OS RACF Security Technical Implementation Guide	2023-06-13

Details

Check Text ( C-25530r868905_chk )
From ISPF Command Shell enter: Listgrp * OMVS If each group is defined with a unique GID, this is not a finding. Note: A site can choose to have both an OMVSGRP group and an STCOMVS group or combine the groups under one of these names. If OMVSGRP and/or STCOMVS groups are defined and have a unique GID in the range of 1-99, this is not a finding.

Fix Text (F-25518r868906_fix)
Define each UNIX group with a unique GID. Define the OMVSGRP group and/or the STCOMVS group to the security database with a unique GID in the range of 1-99. OMVSGRP is the name suggested by IBM for all the required userids. STCOMVS is the standard name used at some sites for the userids that are associated with z/OS UNIX started tasks and daemons. These groups can be combined at the site's discretion.

Fix Text (F-25518r868906_fix)

Define each UNIX group with a unique GID.

Define the OMVSGRP group and/or the STCOMVS group to the security database with a unique GID in the range of 1-99.

OMVSGRP is the name suggested by IBM for all the required userids. STCOMVS is the standard name used at some sites for the userids that are associated with z/OS UNIX started tasks and daemons. These groups can be combined at the site's discretion.