Contractors creating, storing, processing, or transmitting CUI on behalf of government customers must consider the NIST SP 800-171, the NIST SP 800-171A Assessing Security Requirements for Controlled Unclassified Information, and the NIST SP 800-171 DoD Assessment Methodology when crafting responses to requirements.

NIST SP 800-171 rev 2 contains 110 controls, spread across fourteen (14) control families. Each of these controls has a single written requirement. For example:

3.1.1: Limit system access to authorized users, processes acting on behalf of authorized users, and devices (including other systems)

The NIST SP 800-171 rev 2 template contains only this statement, which at face value appears to be straightforward. However, consider the assessment criteria contained in 171A and DoD Assessment Methodology:

ASSESSMENT OBJECTIVE

Determine if:

3.1.1[a] authorized users are identified.

3.1.1[b] processes acting on behalf of authorized users are identified.

3.1.1[c] devices (and other systems) authorized to connect to the system are identified.

3.1.1[d] system access is limited to authorized users.

3.1.1[e] system access is limited to processes acting on behalf of authorized users.

3.1.1[f] system access is limited to authorized devices (including other systems).

Control Family: Access Control

Basic or Derived Requirement: Basic

SPRS Point Value: 5

CSF v1.1 References: PR.AC-3, PR.AC-4, PR.PT-3

NIST SP 800-53 control mapping: AC-2, AC-3, AC-17

NIST SP 800-171 Discussion:

Access control policies (e.g., identity- or role-based policies, control matrices, and cryptography) control access between active entities or subjects (i.e., users or processes acting on behalf of users) and passive entities or objects (e.g., devices, files, records, and domains) in systems. Access enforcement mechanisms can be employed at the application and service level to provide increased information security. Other systems include systems internal and external to the organization. This requirement focuses on account management for systems and applications. The definition of and enforcement of access authorizations, other than those determined by account type (e.g., privileged verses non-privileged) are addressed in requirement 3.1.2.

NIST SP 800-171A POTENTIAL ASSESSMENT METHODS AND OBJECTS

Examine: [SELECT FROM: Access control policy; procedures addressing account management; system security plan; system design documentation; system configuration settings and associated documentation; list of active system accounts and the name of the individual associated with each account; notifications or records of recently transferred, separated, or terminated employees; list of conditions for group and role membership; list of recently disabled system accounts along with the name of the individual associated with each account; access authorization records; account management compliance reviews; system monitoring records; system audit logs and records; list of devices and systems authorized to connect to organizational systems; other relevant documents or records].

Interview: [SELECT FROM: Personnel with account management responsibilities; system or network administrators; personnel with information security responsibilities].

Test: [SELECT FROM: Organizational processes for managing system accounts; mechanisms for implementing account management].