AC-2: ACCOUNT MANAGEMENT
TAILORED FOR INDUSTRIAL CONTROL SYSTEMS
ICS Control Baselines:
- Low
- Moderate
- High
The organization:
- a. Identifies and selects the following types of information system accounts to support organizational missions/business functions: [Assignment: organization-defined information system account types];
- b. Assigns account managers for information system accounts;
- c. Establishes conditions for group and role membership;
- d. Specifies authorized users of the information system, group and role membership, and access authorizations (i.e., privileges) and other attributes (as required) for each account;
- e. Requires approvals by [Assignment: organization-defined personnel or roles] for requests to create information system accounts;
- f. Creates, enables, modifies, disables, and removes information system accounts in accordance with [Assignment: organization-defined procedures or conditions];
- g. Monitors the use of information system accounts;
- h. Notifies account managers:
- When accounts are no longer required;
- When users are terminated or transferred; and
- When individual information system usage or need-to-know changes;
- i. Authorizes access to the information system based on:
- A valid access authorization;
- Intended system usage; and
- Other attributes as required by the organization or associated missions/business functions;
- j. Reviews accounts for compliance with account management requirements [Assignment: organization-defined frequency]; and
- k. Establishes a process for reissuing shared/group account credentials (if deployed) when individuals are removed from the group.
SUPPLEMENTAL GUIDANCE
Information system account types include, for example, individual, shared, group, system, guest/anonymous, emergency, developer/manufacturer/vendor, temporary, and service. Some of the account management requirements listed above can be implemented by organizational information systems. The identification of authorized users of the information system and the specification of access privileges reflects the requirements in other security controls in the security plan. Users requiring administrative privileges on information system accounts receive additional scrutiny by appropriate organizational personnel (e.g., system owner, mission/business owner, or chief information security officer) responsible for approving such accounts and privileged access. Organizations may choose to define access privileges or other attributes by account, by type of account, or a combination of both. Other attributes required for authorizing access include, for example, restrictions on time-of-day, day-of-week, and point-of-origin. In defining other account attributes, organizations consider system-related requirements (e.g., scheduled maintenance, system upgrades) and mission/business requirements, (e.g., time zone differences, customer requirements, remote access to support travel requirements). Failure to consider these factors could affect information system availability. Temporary and emergency accounts are accounts intended for short-term use. Organizations establish temporary accounts as a part of normal account activation procedures when there is a need for short-term accounts without the demand for immediacy in account activation. Organizations establish emergency accounts in response to crisis situations and with the need for rapid account activation. Therefore, emergency account activation may bypass normal account authorization processes. Emergency and temporary accounts are not to be confused with infrequently used accounts (e.g., local logon accounts used for special tasks defined by organizations or when network resources are unavailable). Such accounts remain available and are not subject to automatic disabling or removal dates. Conditions for disabling or deactivating accounts include, for example: (i) when shared/group, emergency, or temporary accounts are no longer required; or (ii) when individuals are transferred or terminated. Some types of information system accounts may require specialized training.
ICS SUPPLEMENTAL GUIDANCE
Example compensating controls include providing increased physical security, personnel security, intrusion detection, auditing measures.
RELATED CONTROLS: AC-2
CONTROL ENHANCEMENTS
AC-2 (1) ACCOUNT MANAGEMENT | AUTOMATED SYSTEM ACCOUNT MANAGEMENT
ICS Control Baselines:
- Moderate
- High
The organization employs automated mechanisms to support the management of information system accounts.
Supplemental Guidance:
The use of automated mechanisms can include, for example: using email or text messaging to automatically notify account managers when users are terminated or transferred; using the information system to monitor account usage; and using telephonic notification to report atypical system account usage.
AC-2 (2) ACCOUNT MANAGEMENT | REMOVAL OF TEMPORARY / EMERGENCY ACCOUNTS
ICS Control Baselines:
- Moderate
- High
The information system automatically [Selection: removes; disables] temporary and emergency accounts after [Assignment: organization-defined time period for each type of account].
Supplemental Guidance:
This control enhancement requires the removal of both temporary and emergency accounts automatically after a predefined period of time has elapsed, rather than at the convenience of the systems administrator.
ICS SUPPLEMENTAL GUIDANCE:
In situations where the ICS (e.g., field devices) cannot support temporary or emergency accounts, this enhancement does not apply. Example compensating controls include employing nonautomated mechanisms or procedures.
AC-2 (3) ACCOUNT MANAGEMENT | DISABLE INACTIVE ACCOUNTS
ICS Control Baselines:
- Moderate
- High
The information system automatically disables inactive accounts after [Assignment: organization-defined time period].
Supplemental Guidance: NONE
ICS SUPPLEMENTAL GUIDANCE:
Example compensating controls include employing nonautomated mechanisms or procedures.
AC-2 (4) ACCOUNT MANAGEMENT | AUTOMATED AUDIT ACTIONS
ICS Control Baselines:
- Moderate
- High
The information system automatically audits account creation, modification, enabling, disabling, and removal actions, and notifies [Assignment: organization-defined personnel or roles].
Supplemental Guidance: NONE
ICS SUPPLEMENTAL GUIDANCE:
Example compensating controls include employing nonautomated mechanisms or procedures.
RELATED CONTROLS: AC-2 (4)
AC-2 (5) ACCOUNT MANAGEMENT | INACTIVITY LOGOUT
ICS Control Baselines:
- Moderate
- High
The organization requires that users log out when [Assignment: organization-defined time-period of expected inactivity or description of when to log out].
Supplemental Guidance: NONE
ICS SUPPLEMENTAL GUIDANCE:
Example compensating controls include employing nonautomated mechanisms or procedures.
RELATED CONTROLS: AC-2 (5)
AC-2 (6) ACCOUNT MANAGEMENT | DYNAMIC PRIVILEGE MANAGEMENT
NOT SELECTED FOR THE NIST ISC CONTROL SET
The information system implements the following dynamic privilege management capabilities: [Assignment: organization-defined list of dynamic privilege management capabilities].
Supplemental Guidance:
In contrast to conventional access control approaches which employ static information system accounts and predefined sets of user privileges, dynamic access control approaches (e.g., service-oriented architectures) rely on run time access control decisions facilitated by dynamic privilege management. While user identities may remain relatively constant over time, user privileges may change more frequently based on ongoing mission/business requirements and operational needs of organizations. Dynamic privilege management can include, for example, the immediate revocation of privileges from users, as opposed to requiring that users terminate and restart their sessions to reflect any changes in privileges. Dynamic privilege management can also refer to mechanisms that change the privileges of users based on dynamic rules as opposed to editing specific user profiles. This type of privilege management includes, for example, automatic adjustments of privileges if users are operating out of their normal work times, or if information systems are under duress or in emergency maintenance situations. This control enhancement also includes the ancillary effects of privilege changes, for example, the potential changes to encryption keys used for communications. Dynamic privilege management can support requirements for information system resiliency.
RELATED CONTROLS: AC-2 (6)
AC-2 (7) ACCOUNT MANAGEMENT | ROLE-BASED SCHEMES
NOT SELECTED FOR THE NIST ISC CONTROL SET
The organization:
- (a) Establishes and administers privileged user accounts in accordance with a role-based access scheme that organizes allowed information system access and privileges into roles;
- (b) Monitors privileged role assignments; and
- (c) Takes [Assignment: organization-defined actions] when privileged role assignments are no longer appropriate.
Supplemental Guidance:
Privileged roles are organization-defined roles assigned to individuals that allow those individuals to perform certain security-relevant functions that ordinary users are not authorized to perform. These privileged roles include, for example, key management, account management, network and system administration, database administration, and web administration.
RELATED CONTROLS: AC-2 (8)
AC-2 (8) ACCOUNT MANAGEMENT | DYNAMIC ACCOUNT CREATION
NOT SELECTED FOR THE NIST ISC CONTROL SET
The information system creates [Assignment: organization-defined information system accounts] dynamically.
Supplemental Guidance:
Dynamic approaches for creating information system accounts (e.g., as implemented within service-oriented architectures) rely on establishing accounts (identities) at run time for entities that were previously unknown. Organizations plan for dynamic creation of information system accounts by establishing trust relationships and mechanisms with the appropriate authorities to validate related authorizations and privileges.
AC-2 (9) ACCOUNT MANAGEMENT | RESTRICTIONS ON USE OF SHARED / GROUP ACCOUNTS
NOT SELECTED FOR THE NIST ISC CONTROL SET
The organization only permits the use of shared/group accounts that meet [Assignment: organization-defined conditions for establishing shared/group accounts].
Supplemental Guidance: NONE
AC-2 (10) ACCOUNT MANAGEMENT | SHARED/GROUP ACCOUNT CREDENTIAL TERMINATION
NOT SELECTED FOR THE NIST ISC CONTROL SET
The information system terminates shared/group account credentials when members leave the group.
Supplemental Guidance: NONE
AC-2 (11) ACCOUNT MANAGEMENT | USAGE CONDITIONS
ISC Control Baseline:
- High
The information system enforces [Assignment: organization-defined circumstances and/or usage conditions] for [Assignment: organization-defined information system accounts].
Supplemental Guidance:
Organizations can describe the specific conditions or circumstances under which information system accounts can be used, for example, by restricting usage to certain days of the week, time of day, or specific durations of time.
AC-2 (12) ACCOUNT MANAGEMENT | ACCOUNT MONITORING/ATYPICAL USAGE
ISC Control Baseline:
- High
The organization:
- (a) Monitors information system accounts for [Assignment: organization-defined atypical usage]; and
- (b) Reports atypical usage of information system accounts to [Assignment: organization-defined personnel or roles].
Supplemental Guidance:
Atypical usage includes, for example, accessing information systems at certain times of the day and from locations that are not consistent with the normal usage patterns of individuals working in organizations.
RELATED CONTROLS: AC-2 (12)
AC-2 (13) ACCOUNT MANAGEMENT | DISABLE ACCOUNTS FOR HIGH-RISK INDIVIDUALS
ISC Control Baseline:
- High
The organization disables accounts of users posing a significant risk within [Assignment: organization-defined time period] of discovery of the risk.
Supplemental Guidance:
Users posing a significant risk to organizations include individuals for whom reliable evidence or intelligence indicates either the intention to use authorized access to information systems to cause harm or through whom adversaries will cause harm. Harm includes potential adverse impacts to organizational operations and assets, individuals, other organizations, or the Nation. Close coordination between authorizing officials, information system administrators, and human resource managers is essential in order for timely execution of this control enhancement.
RELATED CONTROLS: AC-2 (13)
REFERENCES:
- NIST Special Publication 800-82 | GUIDE TO INDUSTRIAL CONTROL SYSTEMS (ICS) SECURITY