NIST SP 800-18r1 Executive Summary
The objective of system security planning is to improve protection of information system resources. All federal systems have some level of sensitivity and require protection as part of good management practice. The protection of a system must be documented in a system security plan. The completion of system security plans is a requirement of the Office of Management and Budget (OMB) Circular A-130, "Management of Federal Information Resources," Appendix III, "Security of Federal Automated Information Resources," and" Title III of the E-Government Act, entitled the Federal Information Security Management Act (FISMA).
The purpose of the system security plan is to provide an overview of the security requirements of the system and describe the controls in place or planned for meeting those requirements. The system security plan also delineates responsibilities and expected behavior of all individuals who access the system. The system security plan should be viewed as documentation of the structured process of planning adequate, cost-effective security protection for a system. It should reflect input from various managers with responsibilities concerning the system, including information owners, the system owner, and the senior agency information security officer (SAISO). Additional information may be included in the basic plan and the structure and format organized according to agency needs, so long as the major sections described in this document are adequately covered and readily identifiable.
In order for the plans to adequately reflect the protection of the resources, a senior management official must authorize a system to operate. The authorization of a system to process information, granted by a management official, provides an important quality control. By authorizing processing in a system, the manager accepts its associated risk.
Management authorization should be based on an assessment of management, operational, and technical controls. Since the system security plan establishes and documents the security controls, it should form the basis for the authorization, supplemented by the assessment report and the plan of actions and milestones. In addition, a periodic review of controls should also contribute to future authorizations. Re-authorization should occur whenever there is a significant change in processing, but at least every three years.