CA-TSS must limit Write or greater access to SYS1.NUCLEUS to system programmers only.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-223900	TSS0-ES-000270	SV-223900r561402_rule		High

Description
To mitigate the risk of unauthorized access to sensitive information by entities that have been issued certificates by DoD-approved PKIs, all DoD systems (e.g., web servers and web portals) must be properly configured to incorporate access control methods that do not rely solely on the possession of a certificate for access. Successful authentication must not automatically give an entity access to an asset or security boundary. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement. Access control policies include: identity-based policies, role-based policies, and attribute-based policies. Access enforcement mechanisms include: access control lists, access control matrices, and cryptography. These policies and mechanisms must be employed by the application to control access between users (or processes acting on behalf of users) and objects (e.g., devices, files, records, processes, programs, and domains) in the information system. Satisfies: SRG-OS-000080-GPOS-00048, SRG-OS-000259-GPOS-00100, SRG-OS-000324-GPOS-00125

Description

To mitigate the risk of unauthorized access to sensitive information by entities that have been issued certificates by DoD-approved PKIs, all DoD systems (e.g., web servers and web portals) must be properly configured to incorporate access control methods that do not rely solely on the possession of a certificate for access. Successful authentication must not automatically give an entity access to an asset or security boundary. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement. Access control policies include: identity-based policies, role-based policies, and attribute-based policies. Access enforcement mechanisms include: access control lists, access control matrices, and cryptography. These policies and mechanisms must be employed by the application to control access between users (or processes acting on behalf of users) and objects (e.g., devices, files, records, processes, programs, and domains) in the information system. Satisfies: SRG-OS-000080-GPOS-00048, SRG-OS-000259-GPOS-00100, SRG-OS-000324-GPOS-00125

STIG	Date
IBM z/OS TSS Security Technical Implementation Guide	2021-03-30

Details

Check Text ( C-25573r516099_chk )
Execute a dataset list of access for SYS1.NUCLEUS. If all of the following are untrue, there is not a finding. If any of the following is true, this is a finding. The ACP data set rules for SYS1.NUCLEUS do not restrict WRITE or greater access to only z/OS systems programming personnel. The ACP data set rules for SYS1.NUCLEUS do not specify that all (i.e., failures and successes) WRITE or greater access will be logged.

Check Text ( C-25573r516099_chk )

Execute a dataset list of access for SYS1.NUCLEUS.

If all of the following are untrue, there is not a finding.

If any of the following is true, this is a finding.

The ACP data set rules for SYS1.NUCLEUS do not restrict WRITE or greater access to only z/OS systems programming personnel.
The ACP data set rules for SYS1.NUCLEUS do not specify that all (i.e., failures and successes) WRITE or greater access will be logged.

Fix Text (F-25561r516100_fix)
Review access authorization to critical system files. Evaluate the impact of correcting the deficiency. Develop a plan of action and implement the changes required to protect SYS1.NUCLEUS. Configure the WRITE or greater access to SYS1.NUCLEUS to be limited to system programmers only and all WRITE or greater access is logged.