cyberstrikeus 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
- NIST SP 800-53 Rev 5 - SC-7(4)
- NIST SP 800-53A Rev 5 (Assessment Procedures)
- NIST SP 800-53 Rev 5 Full Catalog
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