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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-7050	ZUSS0048	SV-7433r5_rule		Medium

Description
User identifiers (ACF2 logonids, RACF userids, and Top Secret ACIDs) that use z/OS UNIX facilities are defined to an ACP with attributes defined in the STIG. If these attributes are not correctly defined, data access or command privilege controls could be compromised.

STIG	Date
z/OS ACF2 STIG	2019-12-12

Details

Check Text ( C-5460r4_chk )
If this is a classified system this is not applicable. From an ACF2 command line enter: SET CONTROL(GSO) SHOW UNIXOPTS Alternately: Refer to the following report produced by the ACF2 Data Collection: - ACF2CMDS.RPT(ACFGSO) - ACF2CMDS.RPT(OMVSUSER) Note: This check applies to any user identifier (LOGONID) used to model OMVS access on the mainframe. This includes any DFTUSER; MODLUSER and BPX.UNIQUE.USER. If MODLUSER is specified then UNIQUSER must be specified. If DFTUSER or MODLUSER is not defined in the UNIXOPTS record there is no finding. If ALL user identifiers (LOGONID) defined to DFTUSER or MODLUSER. or BPX.UNIQUE.USER user account is defined as follows, there is no 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).

Check Text ( C-5460r4_chk )

If this is a classified system this is not applicable.
From an ACF2 command line enter:
SET CONTROL(GSO)
SHOW UNIXOPTS
Alternately:
Refer to the following report produced by the ACF2 Data Collection:

- ACF2CMDS.RPT(ACFGSO)
- ACF2CMDS.RPT(OMVSUSER)

Note: This check applies to any user identifier (LOGONID) used to model OMVS access on the mainframe. This includes any DFTUSER; MODLUSER and BPX.UNIQUE.USER. If MODLUSER is specified then UNIQUSER must be specified.

If DFTUSER or MODLUSER is not defined in the UNIXOPTS record there is no finding.

If ALL user identifiers (LOGONID) defined to DFTUSER or MODLUSER. or BPX.UNIQUE.USER user account is defined as follows, there is no 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 (F-75873r3_fix)
Ensure that the below options are enforced. Note: This only applies to DFTUSER or MODLUSER or BPX.UNIQUE.USER as appropriate. Ensure that DFTUSER or MODLUSER or BPX.UNIQUE.USER user account is defined as follows: 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). Example: SET PROFILE(USER) DIV(OMVS) LIST OMVS INSERT OMVS HOME(/) OMVSPGM(/bin/false) UID(0)

Fix Text (F-75873r3_fix)

Ensure that the below options are enforced.

Note: This only applies to DFTUSER or MODLUSER or BPX.UNIQUE.USER as appropriate.

Ensure that DFTUSER or MODLUSER or BPX.UNIQUE.USER user account is defined as follows:

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).

Example:
SET PROFILE(USER) DIV(OMVS)
LIST OMVS

INSERT OMVS HOME(/) OMVSPGM(/bin/false) UID(0)