What evidence do auditors commonly ask for on SA-20 Customized Development of Critical Components?

Identification of components where market supply is inadequate; Decision records on custom development; Assurance arrangements for custom components.

What is the most common gap auditors find on SA-20?

critical dependency on a component nobody has assessed and no alternative considered

NIST SP 800-161 Rev 1 (supply chain) · C-SCRM Family: System and Services Acquisition

`SA-20` Customized Development of Critical Components

Considers building or customizing critical components where the market cannot supply them at the assurance level required.

Source: NIST SP 800-161 Rev 1 (supply chain), SA-20. 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 800-161 Rev 1 (supply chain) in the compliance library.

artefacts

held by a system

at each review

hard

to go live

Document repository

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

Decision records on custom development · Document repository

governing documentDocuments that govern the control

Identification of components where market supply is inadequate · Document repository
Assurance arrangements for custom components · Document repository

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

critical dependency on a component nobody has assessed and no alternative considered

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 sheet

SA-17 Developer Security and Privacy Architecture and Design · SA-21 Developer Screening