This chapter describes fourteen families of security requirements (including basic and derived requirements) for protecting the confidentiality of CUI in nonfederal systems and organizations.18
The security controls from NIST Special Publication 800-53 associated with the basic and derived requirements are also listed in Appendix D.19 Organizations can use Special Publication 800-53 to obtain additional, non-prescriptive information related to the security requirements (e.g., supplemental guidance related to each of the referenced security controls, mapping tables to ISO/IEC security controls, and a catalog of optional controls that can be used to help specify additional security requirements if needed).
This information can help clarify or interpret the requirements in the context of mission and business requirements, operational environments, or assessments of risk. Nonfederal organizations can implement a variety of potential security solutions either directly or through the use of managed services, to satisfy the security requirements and may implement alternative, but equally effective, security measures to compensate for the inability to satisfy a particular requirement.20
Nonfederal organizations should describe in a system security plan, how the specified security requirements are met or how organizations plan to meet the requirements. The plan describes the system boundary; the operational environment; how the security requirements are implemented; and the relationships with or connections to other systems. Nonfederal organizations should develop plans of action that describe how any unimplemented security requirements will be met and how any planned mitigations will be implemented. Organizations can document the system security plan and plan of action as separate or combined documents and in any chosen format.
When requested, the system security plan and any associated plans of action for any planned implementations or mitigations should be submitted to the responsible federal agency/contracting officer to demonstrate the nonfederal organization’s implementation or planned implementation of the security requirements. Federal agencies may consider the submitted system security plans and plans of action as critical inputs to an overall risk management decision to process, store, or transmit CUI on a system hosted by a nonfederal organization and whether or not it is advisable to pursue an agreement or contract with the nonfederal organization.
The security requirements in this publication should be applied to the nonfederal organization’s internal systems processing, storing, or transmitting CUI. Some systems, including specialized systems (e.g., industrial/process control systems, Computer Numerical Control machines, medical devices), may have restrictions or limitations on the application of certain security requirements. To accommodate such issues, the system security plan, as reflected in Requirement 3.12.4, should be used to describe any enduring exceptions to the security requirements. Individual, isolated, or temporary deficiencies should be managed though plans of action, as reflected in Requirement 3.12.2.
18 While the purpose of this publication is to define requirements to protect the confidentiality of CUI, there is a close relationship between confidentiality and integrity since many of the underlying security mechanisms at the system level support both security objectives. Thus, the integrity requirements (either basic or derived) may have a significant, albeit indirect, effect on the ability of an organization to protect the confidentiality of CUI.
19 The security control references in Appendix D are included to promote a better understanding of the security requirements. The control references are not intended to impose additional requirements on nonfederal organizations. Moreover, because the security controls were developed for federal agencies, the supplemental guidance associated with those controls may not be applicable to nonfederal organizations.
20 To promote consistency, transparency, and comparability, compensatory security measures selected by organizations should be based on or derived from existing and recognized security standards and control sets, including, for example: ISO/IEC 27001 or NIST Special Publication 800-53.