Sa 9 3 Establish And Maintain Trust

---
name: "SA-9(3)_establish-and-maintain-trust-relationship-with-providers"
description: "Establish, document, and maintain trust relationships with external service providers based on the following requirements, properties, factors, or con"
category: "configuration"
version: "5.2.0"
author: "cyberstrike-official"
tags:
  - nist
  - sp800-53
  - rev5
  - sa-9-3
  - sa
  - enhancement
tech_stack:
  - any
cwe_ids:
  - CWE-16
chains_with:
  - SR-2
prerequisites:
  - SA-9
severity_boost:
  SR-2: "Chain with SR-2 for comprehensive security coverage"
---

# SA-9(3) Establish and Maintain Trust Relationship with Providers

> **Enhancement of:** SA-9

## High-Level Description

**Family:** System and Services Acquisition (SA)
**Framework:** NIST SP 800-53 Rev 5

Trust relationships between organizations and external service providers reflect the degree of confidence that the risk from using external services is at an acceptable level. Trust relationships can help organizations gain increased levels of confidence that service providers are providing adequate protection for the services rendered and can also be useful when conducting incident response or when planning for upgrades or obsolescence. Trust relationships can be complicated due to the potentially large number of entities participating in the consumer-provider interactions, subordinate relationships and levels of trust, and types of interactions between the parties. In some cases, the degree of trust is based on the level of control that organizations can exert on external service providers regarding the controls necessary for the protection of the service, information, or individual privacy and the evidence brought forth as to the effectiveness of the implemented controls. The level of control is established by the terms and conditions of the contracts or service-level agreements.

## What to Check

- [ ] Verify SA-9(3) Establish and Maintain Trust Relationship with Providers is documented in SSP
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for SA-9(3)
- [ ] Verify enhancement builds upon base control SA-9

## How to Test

### Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SA-9(3) implementation details. Verify the organization has documented how this control is satisfied.

### Step 2: Validate Implementation

```
# For cloud environments, use cloud-audit-mcp tools
# For on-premises, review system configurations directly

# Example: Check if account management policies exist
grep -r "account.management\|access.control" /etc/security/ 2>/dev/null
```

### Step 3: Test Operating Effectiveness

Verify the control is actively functioning, not just documented. Check logs, configurations, and operational evidence.

## Tools

| Tool          | Purpose                           | Usage |
| ------------- | --------------------------------- | ----- |
| Manual Review | Documentation and interview-based | N/A   |

## Remediation Guide

### Control Statement

Establish, document, and maintain trust relationships with external service providers based on the following requirements, properties, factors, or conditions: [organization-defined].

### Implementation Guidance

Trust relationships between organizations and external service providers reflect the degree of confidence that the risk from using external services is at an acceptable level. Trust relationships can help organizations gain increased levels of confidence that service providers are providing adequate protection for the services rendered and can also be useful when conducting incident response or when planning for upgrades or obsolescence. Trust relationships can be complicated due to the potentially large number of entities participating in the consumer-provider interactions, subordinate relationships and levels of trust, and types of interactions between the parties. In some cases, the degree of trust is based on the level of control that organizations can exert on external service providers regarding the controls necessary for the protection of the service, information, or individual privacy and the evidence brought forth as to the effectiveness of the implemented controls. The level of control is established by the terms and conditions of the contracts or service-level agreements.

## Risk Assessment

| Finding                                                                          | Severity | Impact                                     |
| -------------------------------------------------------------------------------- | -------- | ------------------------------------------ |
| SA-9(3) Establish and Maintain Trust Relationship with Providers not implemented | Medium   | System and Services Acquisition            |
| SA-9(3) partially implemented                                                    | Low      | Incomplete System and Services Acquisition |

## CWE Categories

| CWE ID | Title         |
| ------ | ------------- |
| CWE-16 | Configuration |

## References

- [NIST SP 800-53 Rev 5 - SA-9(3)](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=sa-9.3)
- [NIST SP 800-53A Rev 5 (Assessment Procedures)](https://csrc.nist.gov/pubs/sp/800/53/a/r5/final)
- [NIST SP 800-53 Rev 5 Full Catalog](https://csrc.nist.gov/pubs/sp/800/53/r5/upd1/final)

## Checklist

- [ ] Control documented in SSP
- [ ] Implementation evidence collected
- [ ] Operating effectiveness validated
- [ ] Continuous monitoring in place
- [ ] Related controls (SR-2) reviewed