CA 9 Internal System Connections

---
name: "CA-9_internal-system-connections"
description: "Authorize internal connections of [organization-defined] to the system;"
category: "configuration"
version: "5.2.0"
author: "cyberstrike-official"
tags:
  - nist
  - sp800-53
  - rev5
  - ca-9
  - ca
tech_stack:
  - any
cwe_ids: []
chains_with:
  - AC-3
  - AC-4
  - AC-18
  - AC-19
  - CM-2
  - IA-3
  - SC-7
  - SI-12
prerequisites: []
severity_boost:
  AC-3: "Chain with AC-3 for comprehensive security coverage"
  AC-4: "Chain with AC-4 for comprehensive security coverage"
  AC-18: "Chain with AC-18 for comprehensive security coverage"
---

# CA-9 Internal System Connections

## High-Level Description

**Family:** Assessment, Authorization, and Monitoring (CA)
**Framework:** NIST SP 800-53 Rev 5

Internal system connections are connections between organizational systems and separate constituent system components (i.e., connections between components that are part of the same system) including components used for system development. Intra-system connections include connections with mobile devices, notebook and desktop computers, tablets, printers, copiers, facsimile machines, scanners, sensors, and servers. Instead of authorizing each internal system connection individually, organizations can authorize internal connections for a class of system components with common characteristics and/or configurations, including printers, scanners, and copiers with a specified processing, transmission, and storage capability or smart phones and tablets with a specific baseline configuration. The continued need for an internal system connection is reviewed from the perspective of whether it provides support for organizational missions or business functions.

## What to Check

- [ ] Verify CA-9 Internal System Connections is documented in SSP
- [ ] Validate all 4 control requirements are implemented
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for CA-9

## How to Test

### Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for CA-9 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

Authorize internal connections of [organization-defined] to the system;
Document, for each internal connection, the interface characteristics, security and privacy requirements, and the nature of the information communicated;
Terminate internal system connections after [organization-defined] ; and
Review [organization-defined] the continued need for each internal connection.

### Implementation Guidance

Internal system connections are connections between organizational systems and separate constituent system components (i.e., connections between components that are part of the same system) including components used for system development. Intra-system connections include connections with mobile devices, notebook and desktop computers, tablets, printers, copiers, facsimile machines, scanners, sensors, and servers. Instead of authorizing each internal system connection individually, organizations can authorize internal connections for a class of system components with common characteristics and/or configurations, including printers, scanners, and copiers with a specified processing, transmission, and storage capability or smart phones and tablets with a specific baseline configuration. The continued need for an internal system connection is reviewed from the perspective of whether it provides support for organizational missions or business functions.

## Risk Assessment

| Finding                                          | Severity | Impact                                               |
| ------------------------------------------------ | -------- | ---------------------------------------------------- |
| CA-9 Internal System Connections not implemented | Medium   | Assessment, Authorization, and Monitoring            |
| CA-9 partially implemented                       | Low      | Incomplete Assessment, Authorization, and Monitoring |

## CWE Categories

| CWE ID | Title                 |
| ------ | --------------------- |
| N/A    | No direct CWE mapping |

## References

- [NIST SP 800-53 Rev 5 - CA-9](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=ca-9)
- [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 (AC-3, AC-4, AC-18, AC-19, CM-2) reviewed