SC-3(5) Security Function Isolation | Layered Structures
Implement security functions as a layered structure minimizing interactions between layers of the design and avoiding any dependence by lower layers on the functionality or correctness of higher layers.
Source: NIST SP 800-53 Rev 5, SC-3(5). The statement above is our statement of the clause, read from the published text and cited so you can check it against the official text, not the instrument verbatim. Open NIST SP 800-53 Rev 5 in the compliance library.
Base controls and their enhancements. Which apply follows the baseline you are assessed against (for example FedRAMP Moderate or High, or the low, moderate and high baselines of SP 800-53B). Text in square brackets is a parameter your organisation sets.
These are the artefacts auditors commonly ask for on this requirement, our guidance rather than text from the standard. Your assessor decides what is sufficient in your context, and asks for samples across the period when a report covers one.
system holds itEvidence a system already holds
none for this control
periodic reviewEvidence produced at each review
- System audit records · Policy repository / GRC workspace
- Test of Organizational processes for implementing security functions as a layered structure that minimizes interactions between layers and avoids dependence by lower layers on functionality/correctness of higher layers; mechanisms supporting and/or implementing security functions as a layered structure · Document repository
governing documentDocuments that govern the control
- System and communications protection policy · Policy repository / GRC workspace
- Procedures addressing security function isolation · Policy repository / GRC workspace
- System design documentation · Document repository
- System configuration settings and associated documentation · Policy repository / GRC workspace
- System security plan · Policy repository / GRC workspace
First move
Common gaps auditors find
- Lower layers of security functions depend on higher layers for correct operation
- Security functions are not implemented as a layered structure
Do this for your whole sheet
Paste the rows you run your controls from and get this mapping for every control at once, with the periodic-review ones flagged and a first move per row. No account for the first run.
Build my evidence sheetSC-3(4) Security Function Isolation | Module Coupling and Cohesiveness · SC-4 Information in Shared System Resources