Performing Risk Assessment
Once the controls implementation are documented, a risk assessment can be performed. A risk assessments starts by identifying potential threats and vulnerabilities, and maps implemented controls to individual vulnerabilities. One then determines risk by calculating the likelihood and impact of any given vulnerability being exploited, taking into account existing controls. The culmination of the risk assessment shows the calculated risk for all vulnerabilities, and describes whether the risk is to accepted or mitigated. If mitigated, one needs to describe what additional SP 800-53 controls will be added to the system. NIST SP 800-30 provides guidance on the risk assessment process.

Certification of System
Once the system documentation and risk assessment is complete, the system needs to have its controls assessed and certified to be functioning appropriately. For systems with a FIPS-199 categorization of Low, a self assessment is sufficient for certification. For systems categorized at higher FIPS-199 levels, a certification performed by an independent 3rd party is required. NIST SP 800-26 provides guidance on the self assessment process. NIST SP 800-53A provides guidance on the assessment methods applicable to individual controls.

Accreditation of System
Once a system has been certified, the security documentation package is reviewed by an accrediting official, who, if satisfied with the documentation and the results of certification, accredits the system by issuing an authorization to operate. This authorization is usually for a 3 year period, and may be contingent on additional controls or processes being implemented. NIST SP 800-37 provides guidance on the certification and accreditation of systems.

Continuous Monitoring
All accredited systems are required to monitor a selected set of security controls for efficacy, and the system documentation is updated to reflect changes and modifications to the system. Significant changes to the security profile of the system should trigger an updated risk assessment, and controls that are significantly modified may need to be re-certified. Guidance on continuous monitoring can be found in NIST SP 800-37 and SP 800-53A.

Above article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Federal Information Security Management Act of 2002".