Title

Attributes of z/OS UNIX user accounts used for account modeling must be defined in accordance with security requirements. (Cat II impact)

Discussion

Top Secret ACIDs that use z/OS UNIX facilities must be properly defined. If these attributes are not correctly defined, data access or command privilege controls could be compromised.

Check Content

If this is a classified system, this is not applicable. From a command line issue the following command: Note: One must have appropriate access to perform this command (have the site security officer issue the command) TSS MODIFY STATUS Examine the following option: UNIQUSER Alternately: Refer to the following report produced by the TSS Data Collection: - TSSCMDS.RPT(STATUS) - TSSCMDS.RPT(OMVSUSER) Note: This check applies to any user identifier (ACID) used to model OMVS access on the mainframe. This includes OMVSUSR; MODLUSER, and BPX.UNIQUE.USER. If MODLUSER is specified then UNIQUSER must be specified as “ON”. If user identifier (ACID) used to model OMVS user account is defined as follows, this is not finding. A non-writable HOME directory Shell program specified as “/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

Use of the OMVS default UID will not be allowed on any classified system. Define the user identifier (ACID) used to model OMVS user account with a non-writable home directory, such as "\" root, and a non-executable, but existing, binary file, "/bin/false" or “/bin/echo.”

Additional Identifiers

Rule ID: SV-7941r5_rule

Vulnerability ID: V-7050

Group Title: ZUSS0048

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.