SA 21 Developer Screening

---
name: "SA-21_developer-screening"
description: "Require that the developer of [organization-defined]: Has appropriate access authorizations as determined by assigned [organization-defined] ; and Sat"
category: "configuration"
version: "5.2.0"
author: "cyberstrike-official"
tags:
  - nist
  - sp800-53
  - rev5
  - sa-21
  - sa
tech_stack:
  - any
cwe_ids:
  - CWE-16
chains_with:
  - PS-2
  - PS-3
  - PS-6
  - PS-7
  - SA-4
  - SR-6
prerequisites: []
severity_boost:
  PS-2: "Chain with PS-2 for comprehensive security coverage"
  PS-3: "Chain with PS-3 for comprehensive security coverage"
  PS-6: "Chain with PS-6 for comprehensive security coverage"
---

# SA-21 Developer Screening

## High-Level Description

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

Developer screening is directed at external developers. Internal developer screening is addressed by [PS-3](#ps-3) . Because the system, system component, or system service may be used in critical activities essential to the national or economic security interests of the United States, organizations have a strong interest in ensuring that developers are trustworthy. The degree of trust required of developers may need to be consistent with that of the individuals who access the systems, system components, or system services once deployed. Authorization and personnel screening criteria include clearances, background checks, citizenship, and nationality. Developer trustworthiness may also include a review and analysis of company ownership and relationships that the company has with entities that may potentially affect the quality and reliability of the systems, components, or services being developed. Satisfying the required access authorizations and personnel screening criteria includes providing a list of all individuals who are authorized to perform development activities on the selected system, system component, or system service so that organizations can validate that the developer has satisfied the authorization and screening requirements.

## What to Check

- [ ] Verify SA-21 Developer Screening is documented in SSP
- [ ] Validate all 2 control requirements are implemented
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for SA-21

## How to Test

### Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SA-21 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

Require that the developer of [organization-defined]:
Has appropriate access authorizations as determined by assigned [organization-defined] ; and
Satisfies the following additional personnel screening criteria: [organization-defined].

### Implementation Guidance

Developer screening is directed at external developers. Internal developer screening is addressed by [PS-3](#ps-3) . Because the system, system component, or system service may be used in critical activities essential to the national or economic security interests of the United States, organizations have a strong interest in ensuring that developers are trustworthy. The degree of trust required of developers may need to be consistent with that of the individuals who access the systems, system components, or system services once deployed. Authorization and personnel screening criteria include clearances, background checks, citizenship, and nationality. Developer trustworthiness may also include a review and analysis of company ownership and relationships that the company has with entities that may potentially affect the quality and reliability of the systems, components, or services being developed. Satisfying the required access authorizations and personnel screening criteria includes providing a list of all individuals who are authorized to perform development activities on the selected system, system component, or system service so that organizations can validate that the developer has satisfied the authorization and screening requirements.

## Risk Assessment

| Finding                                   | Severity | Impact                                     |
| ----------------------------------------- | -------- | ------------------------------------------ |
| SA-21 Developer Screening not implemented | Medium   | System and Services Acquisition            |
| SA-21 partially implemented               | Low      | Incomplete System and Services Acquisition |

## CWE Categories

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

## References

- [NIST SP 800-53 Rev 5 - SA-21](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=sa-21)
- [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 (PS-2, PS-3, PS-6, PS-7, SA-4) reviewed