Description: 

Information flow control regulates where information can travel within a system and between systems (versus who can access the information) and without explicit regard to subsequent accesses to that information. Flow control restrictions include the following: keeping export-controlled information from being transmitted in the clear to the Internet; blocking outside traffic that claims to be from within the organization; restricting requests to the Internet that are not from the internal web proxy server; and limiting information transfers between organizations based on data structures and content.  Organizations commonly use information flow control policies and enforcement mechanisms to control the flow of information between designated sources and destinations (e.g., networks, individuals, and devices) within systems and between interconnected systems. Flow control is based on characteristics of the information or the information path. Enforcement occurs in boundary protection devices (e.g., gateways, routers, guards, encrypted tunnels, firewalls) that employ rule sets or establish configuration settings that restrict system services, provide a packet-filtering capability based on header information, or message-filtering capability based on message content (e.g., implementing key word searches or using document characteristics). Organizations also consider the trustworthiness of filtering and inspection mechanisms (i.e., hardware, firmware, and software components) that are critical to information flow enforcement.  Transferring information between systems representing different security domains with different security policies introduces risk that such transfers violate one or more domain security policies. In such situations, information owners or stewards provide guidance at designated policy enforcement points between interconnected systems. Organizations consider mandating specific architectural solutions when required to enforce specific security policies. Enforcement includes: prohibiting information transfers between interconnected systems (i.e., allowing access only); employing hardware mechanisms to enforce one-way information flows; and implementing trustworthy regrading mechanisms to reassign security attributes and security labels. 


Priority: High 


Category: Identity & Access Management (IAM)


Services Associated with AWS: 

  • Amazon Virtual Private Cloud (VPC), AWS Network Firewall
  • Amazon VPC, AWS Network Firewall
  • AWS Transfer Family
  • AWS Network Firewall, AWS Direct Connect, AWS Transit Gateway
  • Amazon Inspector, AWS Trusted Advisor
  • AWS Identity and Access Management (IAM), AWS Organizations


Objective Evidence:

  • Administrative: documented policies, standards & procedures
  • Administrative: supporting documentation of role-based security training being performed
  • Administrative:  documented Data Flow Diagram (DFD)
  • Technical: screen shot of Data Loss Prevention (DLP) settings
  • Technical: screen shot of content filter settings


Possible Technology Considerations:

  • Data Loss Prevention (DLP)
  • Content / DNS Filtering Solution


What needs to be answered: 

Do people know when they're handling CUI? Does the firewall restrict traffic? 


  • Ensure Proper Configuration of Network Traffic Flow
    Description: This check verifies that network traffic flow is regulated in accordance with approved authorizations, ensuring that CUI is not transmitted in clear to the Internet and external traffic claiming to be from within the organization is blocked.
  • Verify Proper Use of Internal Web Proxy Server
    Description: This check ensures that all requests to the Internet are routed through the internal web proxy server, thereby controlling the flow of information.
  • Validate Information Transfer Limitations
    Description: This check confirms that information transfers between organizations are restricted based on data structures and content, ensuring only approved CUI is shared.
  • Confirm Configuration of Boundary Protection Devices
    Description: This check ensures that boundary protection devices such as gateways, routers, firewalls, and encrypted tunnels are correctly configured to restrict system services and provide packet-filtering based on header information or message content.
  • Validate Trustworthiness of Information Flow Enforcement Mechanisms
    Description: This check confirms that filtering and inspection mechanisms critical to information flow enforcement are trustworthy, thereby mitigating the risks associated with information transfers between systems of different security domains.
  • Verify Compliance with Security Policies during Information Transfers
    Description: This check ensures that architectural solutions mandated to enforce specific security policies are in place when transferring information between interconnected systems representing different security domains.


More details: CUI is not transferred among employees and is contained to the customers who have uploaded the information. Client information not accessible by anyone else, including administrators.