CM-5

CM-5 ACCESS RESTRICTIONS FOR CHANGE

Overview

Number	Title	Impact	Priority	Subject Area
CM-5	Access Restrictions For Change	MODERATE	P1	Configuration Management

Instructions
The organization defines, documents, approves, and enforces physical and logical access restrictions associated with changes to the information system.

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, organizations permit only qualified and authorized individuals to access information systems for purposes of initiating changes, including upgrades and modifications. Organizations maintain records of access to ensure that configuration change control is implemented and to support after-the-fact actions should organizations discover any unauthorized 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 unauthorized changes easy to discover).

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, organizations permit only qualified and authorized individuals to access information systems for purposes of initiating changes, including upgrades and modifications. Organizations maintain records of access to ensure that configuration change control is implemented and to support after-the-fact actions should organizations discover any unauthorized 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 unauthorized changes easy to discover).

Enhancements

CM-5 (1) Automated Access Enforcement / Auditing

HIGH

The information system enforces access restrictions and supports auditing of the enforcement actions.

CM-5 (2) Review System Changes

HIGH

Indications that warrant review of information system changes and the specific circumstances justifying such reviews may be obtained from activities carried out by organizations during the configuration change process.

The organization reviews information system changes Assignment: organization-defined frequency and Assignment: organization-defined circumstances to determine whether unauthorized changes have occurred.

CM-5 (3) Signed Components

HIGH

Software and firmware components prevented from installation unless signed with recognized and approved certificates include, for example, software and firmware version updates, patches, service packs, device drivers, and basic input output system (BIOS) updates. Organizations can identify applicable software and firmware components by type, by specific items, or a combination of both. Digital signatures and organizational verification of such signatures, is a method of code authentication.

The information system prevents the installation of Assignment: organization-defined software and firmware components without verification that the component has been digitally signed using a certificate that is recognized and approved by the organization.

CM-5 (4) Dual Authorization

Organizations employ dual authorization 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 authorization may also be known as two-person control.

The organization enforces dual authorization for implementing changes to Assignment: organization-defined information system components and system-level information.

CM-5 (5) Limit Production / Operational Privileges

In many organizations, 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.

The organization:

CM-5 (5)(a)

Limits privileges to change information system components and system-related information within a production or operational environment; and

CM-5 (5)(b)

Reviews and reevaluates privileges Assignment: organization-defined frequency.

CM-5 (6) Limit Library Privileges

Software libraries include privileged programs.

The organization limits privileges to change software resident within software libraries.

CM-5 (7) Automatic Implementation Of Security Safeguards

Withdrawn: Incorporated into SI-7.