SC-7(4)_external-telecommunications-services

DevOps & Security

Implement a managed interface for each external telecommunication service;

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Source SKILL.md: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/NIST/SP800-53_rev5/SC_system-and-communications-protection/SC-7(4)_external-telecommunications-services/SKILL.md

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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 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 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

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