PR.AC-4: Access permissions and authorizations are managed, incorporating the principles of least privilege and separation of duties

Develop, document, and disseminate to [Assignment: organization-defined personnel or roles]: [Assignment (one or more): organization-level, mission/business process-level, system-level] access control policy that: Addresses purpose, scope, roles, responsibilities, management commitment, coordination among organizational entities, and compliance; and Is consistent with applicable laws, executive orders, directives, regulations, policies, standards, and guidelines; and Procedures to facilitate the implementation…

Define and document the types of accounts allowed and specifically prohibited for use within the system; Assign account managers; Require [Assignment: organization-defined prerequisites and criteria] for group and role membership; Specify: Authorized users of the system; Group and role membership; and Access authorizations (i.e., privileges) and [Assignment: organization-defined attributes (as required)] for each account; Require…

Enforce approved authorizations for logical access to information and system resources in accordance with applicable access control policies.

Identify and document [Assignment: organization-defined duties of individuals requiring separation]; and Define system access authorizations to support separation of duties.

Employ the principle of least privilege, allowing only authorized accesses for users (or processes acting on behalf of users) that are necessary to accomplish assigned organizational tasks.

Identify [Assignment: organization-defined user actions] that can be performed on the system without identification or authentication consistent with organizational mission and business functions; and Document and provide supporting rationale in the security plan for the system, user actions not requiring identification or authentication.

Provide the means to associate [Assignment: organization-defined types of security and privacy attributes] with [Assignment: organization-defined security and privacy attribute values] for information in storage, in process, and/or in transmission; Ensure that the attribute associations are made and retained with the information; Establish the following permitted security and privacy attributes from the attributes defined in…

[Assignment: Establish procedures, Implement mechanisms] to ensure [Assignment: organization-defined access control decisions] are applied to each access request prior to access enforcement.

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…

Organizations may choose to define access privileges or other attributes by account, by type of account, or a combination of both. System account types include individual, shared, group, system, anonymous, guest, emergency, developer, manufacturer, vendor, and temporary. Other attributes required for authorizing access include restrictions on time-of-day, day-of-week, and point-of- origin. In defining other account…

Separation of duties addresses the potential for abuse of authorized privileges and helps to reduce the risk of malevolent activity without collusion. Separation of duties includes dividing mission functions and system support functions among different individuals or roles; conducting system support functions with different individuals (e.g., configuration management, quality assurance and testing, system management, programming,…

Organizations employ the principle of least privilege for specific duties and authorized accesses for users and processes. The principle of least privilege is applied with the goal of authorized privileges no higher than necessary to accomplish required organizational missions or business functions. Organizations consider the creation of additional processes, roles, and system accounts as necessary,…

This requirement limits exposure when operating from within privileged accounts or roles. The inclusion of roles addresses situations where organizations implement access control policies such as role-based access control and where a change of role provides the same degree of assurance in the change of access authorizations for the user and all processes acting on…

Privileged functions include establishing system accounts, performing system integrity checks, conducting patching operations, or administering cryptographic key management activities. Non- privileged users are individuals that do not possess appropriate authorizations. Circumventing intrusion detection and prevention mechanisms or malicious code protection mechanisms are examples of privileged functions that require protection from non-privileged users. Note that this…

This requirement applies regardless of whether the logon occurs via a local or network connection. Due to the potential for denial of service, automatic lockouts initiated by systems are, in most cases, temporary and automatically release after a predetermined period established by the organization (i.e., a delay algorithm). If a delay algorithm is selected, organizations…

Session locks are temporary actions taken when users stop work and move away from the immediate vicinity of the system but do not want to log out because of the temporary nature of their absences. Session locks are implemented where session activities can be determined, typically at the operating system level (but can also be…

This requirement addresses the termination of user-initiated logical sessions in contrast to the termination of network connections that are associated with communications sessions (i.e., disconnecting from the network). A logical session (for local, network, and remote access) is initiated whenever a user (or process acting on behalf of a user) accesses an organizational system. Such…

Multifactor authentication requires the use of two or more different factors to authenticate. The factors are defined as something you know (e.g., password, personal identification number [PIN]); something you have (e.g., cryptographic identification device, token); or something you are (e.g., biometric). Multifactor authentication solutions that feature physical authenticators include hardware authenticators providing time-based or challenge-response…

Authentication processes resist replay attacks if it is impractical to successfully authenticate by recording or replaying previous authentication messages. Replay-resistant techniques include protocols that use nonces or challenges such as time synchronous or challenge-response one-time authenticators. [SP 800-63-3] provides guidance on digital identities.

System management functionality includes functions necessary to administer databases, network components, workstations, or servers, and typically requires privileged user access. The separation of user functionality from system management functionality is physical or logical. Organizations can implement separation of system management functionality from user functionality by using different computers, different central processing units, different instances of…

The control of information in shared system resources (e.g., registers, cache memory, main memory, hard disks) is also commonly referred to as object reuse and residual information protection. This requirement prevents information produced by the actions of prior users or roles (or the actions of processes acting on behalf of prior users or roles) from…