STIG ID - BACF1022: Protect Libraries Included in REXXLIB

Severity
: 1 - High
Libraries included in the system REXXLIB concatenation can contain program modules which include security bypass capabilities. Unauthorized access to the system REXXLIB concatenation could result in the compromise of the operating system environment, external security manager (ESM), and customer data.
The organization must ensure that write or greater access to the system REXXLIB concatenation is limited to system programmers based upon documented roles performed and that all write or greater access is logged.
This STIG article shows how to review the system REXXLIB concatenation and ensure write or greater access to system REXXLIB concatenation is limited to system programmers. Additionally, the organization must ensure that all update or greater access is logged.
Identify Audit Finding
Review the following data to determine if you should consider remediation:
Follow these steps
:
  1. Review access to the system REXXLIB concatenation and ensure the following:.
    • Write or greater access is limited to system programmers.
    • Read access to all users as needed.
    • All write or greater access is logged.
    ACF ACCESS DSN('SYS1.SAXREXEC') ACCESS Subcommand Results as of 07/29/20-12:18 for: SYS1.LINKLIB $Key: SYS1 Ruleline: SAXREXEC UID(*****SYSPROG) READ(A) WRITE(L) ALLOC(L) EXEC(A) ACF
    In this example, the system programmer (SYSPROG) has read, write, and allocate access to REXXLIB and all activity is logged.
  2. Review the output, ensuring the following:
    • Only system programmers have write or greater access.
    • All access greater than read is logged
  3. If write or greater access to REXXLIB is limited to system programmers and activity is logged,
    your organization does not have an audit finding.
  4. If write or greater access to REXXLIB is not limited to system programmers or if write access or greater is not logged,
    your organization has an audit finding.
    See Remediate Audit Findings.
Remediate Audit Finding
The Information System Security Officer (ISSO) is responsible for ensuring that write or greater access to REXXLIB is limited to only system programmers and all activity is logged.
Follow these steps:
  1. Evaluate the impact of correcting the deficiency and develop a plan of action to implement the required changes.
  2. Implement controls to specify only system programmers are authorized to update and alter the REXXLIB.
    $KEY(SYS1) SAXREXEC UID(*****SYSPROG) READ(A) WRITE(L) ALLOC(L) EXEC(A)
    or
    $KEY(SYS1) ROLESET SAXREXEC ROLE(ZSYSPROG) READ(A) WRITE(L) ALLOC(L) EXEC(A)
    The SYSPROG is now authorized to update and alter the SYS1.SAXREXEC.
Implementing controls to the REXXLIB protects your organization's operating system environment, external security manager, and customer data.
Control Correlation Identifier (CCI)
A Control Correlation Identifier (CCI) list provides a standard identifier and description for each of the singular, actionable statements that comprise a control or best practice. The following CCIs are related to this STIG.  For more information, see the National Institute of Standards and Technology website.
CCIs
: CCI-000213, CCI-001499, CCI-002234
CCI
:
CCI-000213
Published Date
:
2009-09-14
Definition
:
The information system enforces approved authorizations for logical access to information and system resources in accordance with applicable access control policies.
Type
:
technical
References
:
NIST: NIST SP 800-53 (v3): CM-5 (6)
NIST: NIST SP 800-53 Revision 4 (v4): AC-3
NIST: NIST SP 800-53A (v1): AC-3.1
CCI
:
CCI-001499
Published Date
:
2009-09-29
Definition
:
The organization limits privileges to change software resident within software libraries.
Type
:
technical
References
:
NIST: NIST SP 800-53 (v3): CM-5 (6)
NIST: NIST SP 800-53 Revision 4 (v4): CM-5 (6)
NIST: NIST SP 800-53A (v1): CM-5 (6).1
CCI
:
CCI-002234
Published Date
:
2013-06-24
Definition
:
The information system audits the execution of privileged functions.
Type
:
technical
References
:
NIST: NIST SP 800-53 Revision 4 (v4): AC-6 (9)