IBM z/OS libraries included in the system REXXLIB concatenation must be properly protected.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-98503	TSS0-ES-000250	SV-107607r1_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	2020-06-29

Details

Check Text ( C-97339r1_chk )
Refer to AXRxx member of PARMLIB for each REXXLIB ADD statement. If the ESM data set rules for libraries in the REXXLIB concatenation restrict WRITE or greater access to only z/OS systems programming personnel, this is not a finding. If the ESM data set rules for libraries in the REXXLIB concatenation restrict READ access to the following, this is not a finding. Appropriate Started Tasks Auditors The user-id defined in PARMLIB member AXR00 AXRUSER(user-id) If the ESM data set rules for libraries in the REXXLIB concatenation specify that all (i.e., failures and successes) WRITE or greater access will be logged, this is not a finding.

Check Text ( C-97339r1_chk )

Refer to AXRxx member of PARMLIB for each REXXLIB ADD statement.

If the ESM data set rules for libraries in the REXXLIB concatenation restrict WRITE or greater access to only z/OS systems programming personnel, this is not a finding.

If the ESM data set rules for libraries in the REXXLIB concatenation restrict READ access to the following, this is not a finding.

Appropriate Started Tasks
Auditors
The user-id defined in PARMLIB member AXR00 AXRUSER(user-id)

If the ESM data set rules for libraries in the REXXLIB concatenation specify that all (i.e., failures and successes) WRITE or greater access will be logged, this is not a finding.

Fix Text (F-104179r1_fix)
Evaluate the impact of correcting the deficiency. Develop a plan of action and implement the changes required to protect APF Authorized Libraries. Configure ESM data set rules to limit WRITE or greater access to libraries included in the system REXXLIB concatenation to system programmers only. Configure ESM data set rules allow READ access to only appropriate Started Tasks and Auditors. Configure ESM data set rules to log WRITE or greater access (i.e., successes and failures).

Fix Text (F-104179r1_fix)

Evaluate the impact of correcting the deficiency. Develop a plan of action and implement the changes required to protect APF Authorized Libraries.

Configure ESM data set rules to limit WRITE or greater access to libraries included in the system REXXLIB concatenation to system programmers only.
Configure ESM data set rules allow READ access to only appropriate Started Tasks and Auditors.
Configure ESM data set rules to log WRITE or greater access (i.e., successes and failures).