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AC-4(4)Information Flow Enforcement | Flow Control of Encrypted Information

IL4 High
IL5
IL6

>Control Description

Prevent encrypted information from bypassing organization-defined information flow control mechanisms by [Selection (one or more): decrypting the information; blocking the flow of the encrypted information; terminating communications sessions attempting to pass encrypted information; organization-defined procedure or method].

>DoD Impact Level Requirements

FedRAMP Parameter Values

AC-4 (4)-1 [intrusion detection mechanisms]

Additional Requirements and Guidance

AC-4 (4) Requirement: The service provider must support Agency requirements to comply with M-21-31 (https://www.whitehouse.gov/wp-content/uploads/2021/08/M-21-31-Improving-the-Federal-Governments-Investigative-and-Remediation-Capabilities-Related-to-Cybersecurity-Incidents.pdf) and M-22-09 (https://www.whitehouse.gov/wp-content/uploads/2022/01/M-22-09.pdf).

>Discussion

Flow control mechanisms include content checking, security policy filters, and data type identifiers. The term encryption is extended to cover encoded data not recognized by filtering mechanisms.

>Programmatic Queries

Beta

Related Services

AWS Network Firewall
AWS WAF
Amazon VPC

CLI Commands

List network firewall policies with TLS inspection
aws network-firewall list-firewall-policies --query 'FirewallPolicies[].{Name:Name,Arn:Arn}'
Describe TLS inspection configuration
aws network-firewall describe-tls-inspection-configuration --tls-inspection-configuration-arn TLS_CONFIG_ARN
Create TLS inspection configuration
aws network-firewall create-tls-inspection-configuration --tls-inspection-configuration-name tls-inspect --tls-inspection-configuration file://tls-config.json
List WAF rules for encrypted traffic inspection
aws wafv2 list-web-acls --scope REGIONAL --query 'WebACLs[].{Name:Name,Id:Id}'

>Related Controls

>Assessment Interview Topics

Questions assessors commonly ask

Process & Governance:

  • What formal policies and procedures govern the implementation of AC-4(4) (Flow Control Of Encrypted Information)?
  • Who are the designated roles responsible for implementing, maintaining, and monitoring AC-4(4)?
  • How frequently is the AC-4(4) policy reviewed and updated, and what triggers policy changes?
  • What training or awareness programs ensure personnel understand their responsibilities related to AC-4(4)?

Technical Implementation:

  • Describe the specific technical mechanisms or controls used to enforce AC-4(4) requirements.
  • What automated tools, systems, or technologies are deployed to implement AC-4(4)?
  • How is AC-4(4) integrated into your system architecture and overall security posture?
  • What configuration settings, parameters, or technical specifications enforce AC-4(4) requirements?

Evidence & Documentation:

  • What documentation demonstrates the complete implementation of AC-4(4)?
  • What audit logs, records, reports, or monitoring data validate AC-4(4) compliance?
  • Can you provide evidence of periodic reviews, assessments, or testing of AC-4(4) effectiveness?
  • What artifacts would you present during a FedRAMP assessment to demonstrate AC-4(4) compliance?

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