IBM z/OS UNIX user accounts must be properly defined.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-223635	ACF2-US-000200	SV-223635r861193_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. Organizational users include organizational employees or individuals the organization deems to have equivalent status of employees (e.g., contractors). Organizational users (and processes acting on behalf of users) must be uniquely identified and authenticated to all accesses, except for the following: 1) Accesses explicitly identified and documented by the organization. Organizations document specific user actions that can be performed on the information system without identification or authentication; and 2) Accesses that occur through authorized use of group authenticators without individual authentication. Organizations may require unique identification of individuals in group accounts (e.g., shared privilege accounts) or for detailed accountability of individual activity.

Description

To assure accountability and prevent unauthenticated access, organizational users must be identified and authenticated to prevent potential misuse and compromise of the system. Organizational users include organizational employees or individuals the organization deems to have equivalent status of employees (e.g., contractors). Organizational users (and processes acting on behalf of users) must be uniquely identified and authenticated to all accesses, except for the following: 1) Accesses explicitly identified and documented by the organization. Organizations document specific user actions that can be performed on the information system without identification or authentication; and 2) Accesses that occur through authorized use of group authenticators without individual authentication. Organizations may require unique identification of individuals in group accounts (e.g., shared privilege accounts) or for detailed accountability of individual activity.

STIG	Date
IBM z/OS ACF2 Security Technical Implementation Guide	2023-09-19

Details

Check Text ( C-25308r858915_chk )
From an ACF Command screen enter: SET PROFILE(USER) DIV(OMVS) LI LIKE(-) If each user account is defined as follows this is not a finding. A unique UID number (except for UID(0) users) Use the following as a quick test for duplicate UIDs apart from UID 0 SHOW OMVS USERS(1-2147483647) DUPLICATES A unique HOME directory (except for UID(0) and other system task accounts) Shell program specified as "/bin/sh", "/bin/tcsh", "/bin/echo", or "/bin/false" NOTE: The shell program must have one of the specified values. The HOME directory must have a value (i.e., not be allowed to default).

Check Text ( C-25308r858915_chk )

From an ACF Command screen enter:

SET PROFILE(USER) DIV(OMVS)

LI LIKE(-)

If each user account is defined as follows this is not a finding.
A unique UID number (except for UID(0) users)
Use the following as a quick test for duplicate UIDs apart from UID 0

SHOW OMVS USERS(1-2147483647) DUPLICATES

A unique HOME directory (except for UID(0) and other system task accounts)
Shell program specified as "/bin/sh", "/bin/tcsh", "/bin/echo", or "/bin/false"

NOTE: The shell program must have one of the specified values. The HOME directory must have a value (i.e., not be allowed to default).

Fix Text (F-25296r504864_fix)
Define any z/OS UNIX user as follows: A unique UID number (except for UID(0) users) A unique HOME directory (except for UID(0) and other system task accounts) Shell program specified as "/bin/sh", "/bin/tcsh", "/bin/echo", or "/bin/false" NOTE: The shell program must have one of the specified values. The HOME directory must have a value (i.e., not be allowed to default).