EvidenceSheet
NIST SP 800-53 Rev 5 · SC - System and Communications Protection

SC-31(2) Covert Channel Analysis | Maximum Bandwidth

Reduce the maximum bandwidth for identified covert Selection (one or more): storage; timing channels to organization-defined values.

Source: NIST SP 800-53 Rev 5, SC-31(2). 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.

10
artefacts
0
held by a system
3
at each review
hard
to go live
Policy repository / GRC workspace
where the evidence lives
teal = a system already holds it · olive = produced at each review. To go live: easy when half or more of the artefacts are already held by a system, moderate from a quarter to a half, hard below a quarter.

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

  • Procedures addressing covert channel analysis · Policy repository / GRC workspace
  • System audit records · Policy repository / GRC workspace
  • Test of Organizational process for conducting covert channel analysis; mechanisms supporting and/or implementing covert channel analysis; mechanisms supporting and/or implementing the capability to reduce the bandwidth of covert channels · Document repository

governing documentDocuments that govern the control

  • System and communications protection policy · Policy repository / GRC workspace
  • Acquisition contracts for systems or services · Vendor register / contract repository
  • Acquisition documentation · Document repository
  • System design documentation · Document repository
  • System configuration settings and associated documentation · Policy repository / GRC workspace
  • Covert channel analysis documentation · Document repository
  • System security plan · Policy repository / GRC workspace

First move

No system holds this evidence for you: it is people and documents. Reminders and routing to the owner still save time. Put the document under version control with an owner and review date, and log each review as a record with reviewer and date.

Common gaps auditors find

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.

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SC-31(1) Covert Channel Analysis | Test Covert Channels for Exploitability · SC-31(3) Covert Channel Analysis | Measure Bandwidth in Operational Environments