KSI-SVC-VCM—Validating Communications
Formerly KSI-SVC-09
>Control Description
>NIST 800-53 Controls
>Trust Center Components3
Ways to express your implementation of this indicator — approaches vary by organization size, complexity, and data sensitivity.
From the field: Mature implementations express communication validation through automated verification — DNS records checked for DMARC/SPF/DKIM enforcement, API gateway metrics showing authentication rates and rejection patterns, and email security configuration grades published as measurable indicators covering both human and machine communication channels.
Communication Validation Architecture
Architecture expressing how inbound/outbound communications are validated — DKIM, SPF, DMARC for email; auth, rate limiting, and validation for APIs
API Security Documentation
API authentication, rate limiting, and input validation controls as product features
Email Security Configuration
DMARC, SPF, and DKIM records with enforcement policy status — verifiable via DNS lookup
>Programmatic Queries
CLI Commands
dig +short TXT _dmarc.example.comdig +short TXT example.com | grep "v=spf1"dig +short TXT selector._domainkey.example.com>20x Assessment Focus Areas
Aligned with FedRAMP 20x Phase Two assessment methodology
Completeness & Coverage:
- •Does communication validation (authenticity and integrity) cover all machine-to-machine communication paths — API calls, database connections, message queue exchanges, and service mesh traffic?
- •Are there inter-resource communication paths where mutual authentication or integrity validation is not implemented, and how are those exceptions documented?
- •How do you ensure communication validation extends to communications with inherited services and third-party integrations?
- •Does integrity validation apply to all data in transit, including control plane communications, not just data plane traffic?
Automation & Validation:
- •What automated mechanisms enforce mutual TLS (mTLS), signed requests, or other integrity validation for inter-resource communications?
- •What happens when communication integrity validation fails — is the connection rejected, retried, or allowed with an alert?
- •How do you detect man-in-the-middle or tampering attempts between resources through integrity validation failures?
- •How do you test that integrity validation mechanisms actually reject tampered or unauthenticated communications?
Inventory & Integration:
- •What tools enforce communication validation (service mesh with mTLS, API gateways with request signing, certificate-based mutual authentication)?
- •How do you maintain an inventory of all inter-resource communication channels and their validation mechanisms?
- •How does your PKI or certificate management system support machine-to-machine authentication at scale?
- •Are communication validation policies (mTLS requirements, signature verification rules) defined as code and version-controlled?
Continuous Evidence & Schedules:
- •How do you demonstrate that communication validation has been persistently active across all inter-resource channels over the past 90 days?
- •Is communication validation status (mTLS enforcement, certificate health, validation failure rates) available via API or dashboard?
- •How do you detect when communication validation coverage degrades — for example, when a new service is deployed without mTLS configuration?
- •What evidence shows communication integrity validation failures are investigated and resolved?
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