NIST SP 800-172 Enhanced Security Requirements for Protecting Controlled Unclassified Information: A Supplement to NIST Special Publication 800-171
NIST SP 800-172 provides federal agencies with a set of enhanced security requirements for protecting the confidentiality, integrity, and availability of CUI: (1) when the CUI is resident in a nonfederal system and organization, (2) when the nonfederal organization is not collecting or maintaining information on behalf of a federal agency or using or operating a system on behalf of an agency, and (3) where there are no specific safeguarding requirements for protecting the CUI prescribed by the authorizing law, regulation, or government-wide policy for the CUI category listed in the CUI Registry.