NIST SP 800-53 SA-17(4) Informal Correspondence

Requirements NIST SOURCE

Require the developer of the system, system component, or system service to:

Discussion (NIST Supplemental Guidance)

Correspondence is an important part of the assurance gained through modeling. It demonstrates that the implementation is an accurate transformation of the model, and that additional code or implementation detail has no impact on the behaviors or policies being modeled. Consistency between the descriptive top-level specification (i.e., high-level/low-level design) and the formal policy model is generally not amenable to being fully proven. Therefore, a combination of formal and informal methods may be needed to show such consistency. Hardware, software, and firmware mechanisms strictly internal to security-relevant hardware, software, and firmware include mapping registers and direct memory input and output.

Implementation Guidance

Engineering Interpretation

Original engineering commentary written for this explorer — not NIST source text and not authoritative guidance.

No engineering interpretation has been authored for SA-17(4) yet. This section is architected to receive it — see the Requirements and Assessment sections above for the authoritative NIST source content in the meantime.

Assessment

NIST SP 800-53A REV 5.2.0

Assessment Objectives

one of the following PARAMETER VALUES is selected: {informal demonstration, convincing argument with formal methods as feasible};
as an integral part of the development process, the developer of the system, system component, or system service is required to produce an informal, descriptive top-level specification that specifies the interfaces to security-relevant hardware, software, and firmware in terms of exceptions;
as an integral part of the development process, the developer of the system, system component, or system service is required to produce an informal, descriptive top-level specification that specifies the interfaces to security-relevant hardware, software, and firmware in terms of error messages;
as an integral part of the development process, the developer of the system, system component, or system service is required to produce an informal, descriptive top-level specification that specifies the interfaces to security-relevant hardware, software, and firmware in terms of effects;
the developer of the system, system component, or system service is required to show via <SA-17(04)_ODP SELECTED PARAMETER VALUE> that the descriptive top-level specification is consistent with the formal policy model;
the developer of the system, system component, or system service is required to show via informal demonstration that the descriptive top-level specification completely covers the interfaces to security-relevant hardware, software, and firmware;
the developer of the system, system component, or system service is required to show that the descriptive top-level specification is an accurate description of the interfaces to security-relevant hardware, software, and firmware;
the developer of the system, system component, or system service is required to describe the security-relevant hardware, software, and firmware mechanisms that are not addressed in the descriptive top-level specification but are strictly internal to the security-relevant hardware, software, and firmware.

Examine

[SELECT FROM: System and services acquisition policy; enterprise architecture policy; formal policy model; procedures addressing developer security architecture and design specifications for the system; solicitation documentation; acquisition documentation; service level agreements; acquisition contracts for the system, system component, or system service; informal, descriptive top-level specification documentation; system security architecture and design documentation; system design documentation; system configuration settings and associated documentation; documentation describing security-relevant hardware, software, and firmware mechanisms not addressed in the informal, descriptive top-level specification documentation; system security plan; other relevant documents or records].

Interview

[SELECT FROM: Organizational personnel with system and service acquisition responsibilities; organizational personnel with information security responsibilities; system developer; organizational personnel with information security architecture and design responsibilities].

Overlays

Showing the OT/ICS overlay for the parent control SA-17 — see the SA-17(4) entries within each baseline below.

OT/ICS Overlay SP 800-82r3

NIST SP 800-82r3 Appendix F, Table 22. Blank baseline means the control/control enhancement is not selected in that initial OT baseline.

LOW

Not applicable at this tier.

MODERATE

Not applicable at this tier.

HIGH

Base control: Included (matches standard baseline)

STIGs & CCIs

No STIG checks or CCI mappings are currently loaded for SA-17(4). This section is architected to display, per product: STIG ID, Finding ID, Severity, Title, Description, Check, Fix, CCI, and NIST control mapping — but nothing is populated here until a real DISA STIG/CCI dataset is ingested.

Learn more about STIG/CCI integration →

Evidence

Potential Evidence — Derived

Categorized from the SP 800-53A "Examine"/"Test" artifact list above by keyword — not an authoritative NIST evidence list.

Policy

System and services acquisition policy
formal policy model
system security plan

Configuration

enterprise architecture policy
procedures addressing developer security architecture and design specifications for the system
system security architecture and design documentation
system design documentation
system configuration settings and associated documentation

Other Records

solicitation documentation
acquisition documentation
service level agreements
acquisition contracts for the system, system component, or system service
informal, descriptive top-level specification documentation
documentation describing security-relevant hardware, software, and firmware mechanisms not addressed in the informal, descriptive top-level specification documentation
other relevant documents or records