SC-21: Secure Name/Address Resolution Service (Recursive or Caching Resolver)

Statement

• Request and perform data origin authentication and data integrity verification on the name/address resolution responses the system receives from authoritative sources.

  • • Requirement:

      Control description should include how DNSSEC is implemented on recursive DNS servers to make DNSSEC requests when resolving DNS requests from internal components to domains external to the CSO boundary.

      • If the reply is signed, and fails DNSSEC, do not use the reply
      • If the reply is unsigned:
        • CSP chooses the policy to apply
    • Requirement:

      Internal recursive DNS servers must be located inside an authorized environment. It is typically within the boundary, or leveraged from an underlying IaaS/PaaS.

    • Guidance:

      Accepting an unsigned reply is acceptable

    • Guidance:

      SC-21 applies to use of internal recursive DNS to access a domain outside the boundary by a component inside the boundary.

      • DNSSEC resolution to access a component inside the boundary is excluded.