Control statement
- a.Identify the following alternative sources of information for [Organization-defined: essential functions and services]: [Organization-defined: alternative information sources] ; and
- b.Use an alternative information source for the execution of essential functions or services on [Organization-defined: systems or system components] when the primary source of information is corrupted or unavailable.
Discussion
Actions taken by a system service or a function are often driven by the information it receives. Corruption, fabrication, modification, or deletion of that information could impact the ability of the service function to properly carry out its intended actions. By having multiple sources of input, the service or function can continue operation if one source is corrupted or no longer available. It is possible that the alternative sources of information may be less precise or less accurate than the primary source of information. But having such sub-optimal information sources may still provide a sufficient level of quality that the essential service or function can be carried out, even in a degraded or debilitated manner.
Organization-defined parameters
These values must be resolved through the organization’s tailoring and governance process. Bracketed parameter references in the control text identify where a decision is required.
From control text to operational evidence
Use Information Diversity as a testable risk decision. Translate the official statement into accountable people, repeatable processes, configured technology, and evidence that demonstrates the outcome over time. In this family, pay particular attention to flaw remediation, malicious-code protection, monitoring, integrity, and trustworthy information handling.
Implementation workflow
- Define the control boundary, responsible owner, inherited portions, and systems or processes in scope.
- Resolve each organization-defined parameter before declaring the control implemented.
- Document how the implementation satisfies every clause of the official control statement.
- Collect evidence as a normal byproduct of operation rather than only before an assessment.
- Review exceptions, changes, and monitoring results on a risk-based cadence.
Evidence examples
- patch and remediation records
- malware protection configuration
- monitoring alerts and response records
- integrity validation and exception reports
Common failure patterns
- patch compliance hides unsupported assets
- alerts generated without response ownership
- exceptions never expire
- integrity monitoring excludes critical configurations
Questions practitioners should ask
- What risk decision is this control intended to support in this system?
- Which parts are implemented locally, inherited, shared, or not applicable—and what evidence supports that decision?
- Do the documented narrative, deployed configuration, operating process, and collected evidence agree?
- What event or threshold requires the implementation to be reviewed or changed?
Assessment objectives and methods
Show the assessment objective
- SI-22a.[Organization-defined: alternative information sources] for [Organization-defined: essential functions and services] are identified;
- SI-22b.an alternative information source is used for the execution of essential functions or services on [Organization-defined: systems or system components] when the primary source of information is corrupted or unavailable.
Examine
- System and information integrity policy
- system and information integrity procedures
- personally identifiable information processing policy
- system design documentation
- system configuration settings and associated documentation
- list of information sources
- system security plan
- privacy plan
- other relevant documents or records
Interview
- Organizational personnel with information security and privacy responsibilities
- organizational personnel with systems security engineering responsibilities
- system developers
Test
- Automated methods and mechanisms to convert information from an analog to digital medium
Authoritative sources
Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. Official control requirements and interpretations remain with NIST and the responsible authorizing organization.