Sc 7 4 External Telecommunications

---
name: "SC-7(4)_external-telecommunications-services"
description: "Implement a managed interface for each external telecommunication service;"
category: "configuration"
version: "5.2.0"
author: "cyberstrike-official"
tags:
  - nist
  - sp800-53
  - rev5
  - sc-7-4
  - sc
  - enhancement
tech_stack:
  - aws
  - azure
  - gcp
  - linux
  - windows
  - network
cwe_ids:
  - CWE-311
chains_with:
  - AC-3
  - SC-8
  - SC-20
  - SC-21
  - SC-22
prerequisites:
  - SC-7
severity_boost:
  AC-3: "Chain with AC-3 for comprehensive security coverage"
  SC-8: "Chain with SC-8 for comprehensive security coverage"
  SC-20: "Chain with SC-20 for comprehensive security coverage"
---

# SC-7(4) External Telecommunications Services

> **Enhancement of:** SC-7

## High-Level Description

**Family:** System and Communications Protection (SC)
**Framework:** NIST SP 800-53 Rev 5

External telecommunications services can provide data and/or voice communications services. Examples of control plane traffic include Border Gateway Protocol (BGP) routing, Domain Name System (DNS), and management protocols. See [SP 800-189](#f5edfe51-d1f2-422e-9b27-5d0e90b49c72) for additional information on the use of the resource public key infrastructure (RPKI) to protect BGP routes and detect unauthorized BGP announcements.

## What to Check

- [ ] Verify SC-7(4) External Telecommunications Services is documented in SSP
- [ ] Validate all 8 control requirements are implemented
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for SC-7(4)
- [ ] Verify enhancement builds upon base control SC-7

## How to Test

### Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SC-7(4) 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                                |
| --------------- | ------------------------------------- | ------------------------------------ |
| cloud-audit-mcp | Check encryption and network controls | `cloud_audit_encryption`             |
| nmap            | Network scanning                      | `nmap -sV --script ssl-enum-ciphers` |

## Remediation Guide

### Control Statement

Implement a managed interface for each external telecommunication service;
Establish a traffic flow policy for each managed interface;
Protect the confidentiality and integrity of the information being transmitted across each interface;
Document each exception to the traffic flow policy with a supporting mission or business need and duration of that need;
Review exceptions to the traffic flow policy [organization-defined] and remove exceptions that are no longer supported by an explicit mission or business need;
Prevent unauthorized exchange of control plane traffic with external networks;
Publish information to enable remote networks to detect unauthorized control plane traffic from internal networks; and
Filter unauthorized control plane traffic from external networks.

### Implementation Guidance

External telecommunications services can provide data and/or voice communications services. Examples of control plane traffic include Border Gateway Protocol (BGP) routing, Domain Name System (DNS), and management protocols. See [SP 800-189](#f5edfe51-d1f2-422e-9b27-5d0e90b49c72) for additional information on the use of the resource public key infrastructure (RPKI) to protect BGP routes and detect unauthorized BGP announcements.

## Risk Assessment

| Finding                                                      | Severity | Impact                                          |
| ------------------------------------------------------------ | -------- | ----------------------------------------------- |
| SC-7(4) External Telecommunications Services not implemented | High     | System and Communications Protection            |
| SC-7(4) partially implemented                                | Medium   | Incomplete System and Communications Protection |

## CWE Categories

| CWE ID  | Title                                |
| ------- | ------------------------------------ |
| CWE-311 | Missing Encryption of Sensitive Data |

## References

- [NIST SP 800-53 Rev 5 - SC-7(4)](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=sc-7.4)
- [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, SC-8, SC-20, SC-21, SC-22) reviewed