Control: The organisation defines, documents, approves, and enforces physical and logical access restrictions associated with changes to the information system.
Supplemental Guidance: Any changes to the hardware, software, and / or firmware components of information systems can potentially have significant effects on the overall security of the systems. Therefore, organisations permit only qualified and authorised individuals to access information systems for purposes of initiating changes, including upgrades and modifications. Organisations maintain records of access to ensure that configuration change control is implemented and to support after-the-fact actions should organisations discover any unauthorised changes. Access restrictions for change also include software libraries. Access restrictions include, for example, physical and logical access controls (see AC-3 and PE-3), workflow automation, media libraries, abstract layers (e.g., changes implemented into third-party interfaces rather than directly into information systems), and change windows (e.g., changes occur only during specified times, making unauthorised changes easy to discover).
Related controls: AC-3, AC-6, PE-3.
Access Restrictions for Change Control Enhancements:
CM-5 (1) Access Restrictions for Change - Automated access enforcement / auditing
The information system enforces access restrictions and supports auditing of the enforcement actions.
Supplemental Guidance: Related controls: AU-2, AU-12, AU-6, CM-3, CM-6.
CM-5 (2) Access Restrictions for Change - Review system changes
The organisation reviews information system changes [Assignment: organisation-defined frequency] and [Assignment: organisation-defined circumstances] to determine whether unauthorised changes have occurred.
Supplemental Guidance: Indications that warrant review of information system changes and the specific circumstances justifying such reviews may be obtained from activities carried out by organisations during the configuration change process.
Related controls: AU-6, AU-7, CM-3, CM-5, PE-6, PE-8.
CM-5 (3) Access Restrictions for Change - Signed Components
The information system prevents the installation of [Assignment: organisation-defined software and firmware components] without verification that the component has been digitally signed using a certificate that is recognised and approved by the organisation.
Supplemental Guidance: Software and firmware components prevented from installation unless signed with recognised and approved certificates include, for example, software and firmware version updates, patches, service packs, device drivers, and basic input output system (BIOS) updates. Organisations can identify applicable software and firmware components by type, by specific items, or a combination of both. Digital signatures and organisational verification of such signatures, is a method of code authentication.
Related controls: CM-7, SC-13, SI-7.
CM-5 (4) Access Restrictions for Change - Dual Authorisation
The organisation enforces dual authorisation for implementing changes to [Assignment: organisation-defined information system components and system-level information].
Supplemental Guidance: Organisations employ dual authorisation to ensure that any changes to selected information system components and information cannot occur unless two qualified individuals implement such changes. The two individuals possess sufficient skills/expertise to determine if the proposed changes are correct implementations of approved changes. Dual authorisation may also be known as two-person control.
Related controls: AC-5, CM-3.
CM-5 (5) Access Restrictions for Change - Limit production / Operation privileges
The organisation:
- (a) Limits privileges to change information system components and system-related information within a production or operational environment; and
- (b) Reviews and reevaluates privileges [Assignment: organisation-defined frequency].
Supplemental Guidance: In many organisations, information systems support multiple core missions/business functions. Limiting privileges to change information system components with respect to operational systems is necessary because changes to a particular information system component may have far-reaching effects on mission/business processes supported by the system where the component resides. The complex, many-to-many relationships between systems and mission/business processes are in some cases, unknown to developers.
Related control: AC-2.
CM-5 (6) Access Restrictions for Change - Limit Library Privileges
The organisation limits privileges to change software resident within software libraries.
Supplemental Guidance: Software libraries include privileged programs.
Related control: AC-2.
CM-5 (7) Access Restrictions for Change - Automatic Implementation of Security Safeguards
[Withdrawn: Incorporated into SI-7].