NIST SP 800-53 Rev. 5 Common Control Library

NIST control statement

a. Identify the types of events that the system is capable of logging in support of the audit function: [Assignment: event types]; b. Coordinate the event logging function with other organizational entities requiring audit-related information to guide and inform the selection criteria for events to be logged; c. Specify the following event types for logging within the system: [Assignment: organization-defined event types (subset of the event types defined in [AU-2a.](#au-2_smt.a)) along with the frequency of (or situation requiring) logging for each identified event type]; d. Provide a rationale for why the event types selected for logging are deemed to be adequate to support after-the-fact investigations of incidents; and e. Review and update the event types selected for logging [Assignment: frequency].

Discussion

An event is an observable occurrence in a system. The types of events that require logging are those events that are significant and relevant to the security of systems and the privacy of individuals. Event logging also supports specific monitoring and auditing needs. Event types include password changes, failed logons or failed accesses related to systems, security or privacy attribute changes, administrative privilege usage, PIV credential usage, data action changes, query parameters, or external credential usage. In determining the set of event types that require logging, organizations consider the monitoring and auditing appropriate for each of the controls to be implemented. For completeness, event logging includes all protocols that are operational and supported by the system. To balance monitoring and auditing requirements with other system needs, event logging requires identifying the subset of event types that are logged at a given point in time. For example, organizations may determine that systems need the capability to log every file access successful and unsuccessful, but not activate that capability except for specific circumstances due to the potential burden on system performance. The types of events that organizations desire to be logged may change. Reviewing and updating the set of logged events is necessary to help ensure that the events remain relevant and continue to support the needs of the organization. Organizations consider how the types of logging events can reveal information about individuals that may give rise to privacy risk and how best to mitigate such risks. For example, there is the potential to reveal personally identifiable information in the audit trail, especially if the logging event is based on patterns or time of usage. Event logging requirements, including the need to log specific event types, may be referenced in other controls and control enhancements. These include [AC-2(4)](#ac-2.4), [AC-3(10)](#ac-3.10), [AC-6(9)](#ac-6.9), [AC-17(1)](#ac-17.1), [CM-3f](#cm-3_smt.f), [CM-5(1)](#cm-5.1), [IA-3(3)(b)](#ia-3.3_smt.b), [MA-4(1)](#ma-4.1), [MP-4(2)](#mp-4.2), [PE-3](#pe-3), [PM-21](#pm-21), [PT-7](#pt-7), [RA-8](#ra-8), [SC-7(9)](#sc-7.9), [SC-7(15)](#sc-7.15), [SI-3(8)](#si-3.8), [SI-4(22)](#si-4.22), [SI-7(8)](#si-7.8) , and [SI-10(1)](#si-10.1) . Organizations include event types that are required by applicable laws, executive orders, directives, policies, regulations, standards, and guidelines. Audit records can be generated at various levels, including at the packet level as information traverses the network. Selecting the appropriate level of event logging is an important part of a monitoring and auditing capability and can identify the root causes of problems. When defining event types, organizations consider the logging necessary to cover related event types, such as the steps in distributed, transaction-based processes and the actions that occur in service-oriented architectures.

NIST control statement

Develop a system-level continuous monitoring strategy and implement continuous monitoring in accordance with the organization-level continuous monitoring strategy that includes: a. Establishing the following system-level metrics to be monitored: [Assignment: system-level metrics]; b. Establishing [Assignment: frequencies] for monitoring and [Assignment: frequencies] for assessment of control effectiveness; c. Ongoing control assessments in accordance with the continuous monitoring strategy; d. Ongoing monitoring of system and organization-defined metrics in accordance with the continuous monitoring strategy; e. Correlation and analysis of information generated by control assessments and monitoring; f. Response actions to address results of the analysis of control assessment and monitoring information; and g. Reporting the security and privacy status of the system to [Assignment: organization-defined personnel or roles] [Assignment: organization-defined frequency].

Discussion

Continuous monitoring at the system level facilitates ongoing awareness of the system security and privacy posture to support organizational risk management decisions. The terms "continuous" and "ongoing" imply that organizations assess and monitor their controls and risks at a frequency sufficient to support risk-based decisions. Different types of controls may require different monitoring frequencies. The results of continuous monitoring generate risk response actions by organizations. When monitoring the effectiveness of multiple controls that have been grouped into capabilities, a root-cause analysis may be needed to determine the specific control that has failed. Continuous monitoring programs allow organizations to maintain the authorizations of systems and common controls in highly dynamic environments of operation with changing mission and business needs, threats, vulnerabilities, and technologies. Having access to security and privacy information on a continuing basis through reports and dashboards gives organizational officials the ability to make effective and timely risk management decisions, including ongoing authorization decisions. Automation supports more frequent updates to hardware, software, and firmware inventories, authorization packages, and other system information. Effectiveness is further enhanced when continuous monitoring outputs are formatted to provide information that is specific, measurable, actionable, relevant, and timely. Continuous monitoring activities are scaled in accordance with the security categories of systems. Monitoring requirements, including the need for specific monitoring, may be referenced in other controls and control enhancements, such as [AC-2g](#ac-2_smt.g), [AC-2(7)](#ac-2.7), [AC-2(12)(a)](#ac-2.12_smt.a), [AC-2(7)(b)](#ac-2.7_smt.b), [AC-2(7)(c)](#ac-2.7_smt.c), [AC-17(1)](#ac-17.1), [AT-4a](#at-4_smt.a), [AU-13](#au-13), [AU-13(1)](#au-13.1), [AU-13(2)](#au-13.2), [CM-3f](#cm-3_smt.f), [CM-6d](#cm-6_smt.d), [CM-11c](#cm-11_smt.c), [IR-5](#ir-5), [MA-2b](#ma-2_smt.b), [MA-3a](#ma-3_smt.a), [MA-4a](#ma-4_smt.a), [PE-3d](#pe-3_smt.d), [PE-6](#pe-6), [PE-14b](#pe-14_smt.b), [PE-16](#pe-16), [PE-20](#pe-20), [PM-6](#pm-6), [PM-23](#pm-23), [PM-31](#pm-31), [PS-7e](#ps-7_smt.e), [SA-9c](#sa-9_smt.c), [SR-4](#sr-4), [SC-5(3)(b)](#sc-5.3_smt.b), [SC-7a](#sc-7_smt.a), [SC-7(24)(b)](#sc-7.24_smt.b), [SC-18b](#sc-18_smt.b), [SC-43b](#sc-43_smt.b) , and [SI-4](#si-4).

NIST control statement

Define, document, approve, and enforce physical and logical access restrictions associated with changes to the system.

Discussion

Changes to the hardware, software, or firmware components of systems or the operational procedures related to the system can potentially have significant effects on the security of the systems or individuals’ privacy. Therefore, organizations permit only qualified and authorized individuals to access systems for purposes of initiating changes. Access restrictions include physical and logical access controls (see [AC-3](#ac-3) and [PE-3](#pe-3) ), software libraries, workflow automation, media libraries, abstract layers (i.e., changes implemented into external interfaces rather than directly into systems), and change windows (i.e., changes occur only during specified times).

NIST control statement

a. Enforce physical access authorizations at [Assignment: entry and exit points] by: 1. Verifying individual access authorizations before granting access to the facility; and 2. Controlling ingress and egress to the facility using [Selection (one-or-more): [Assignment: systems or devices] ; guards]; b. Maintain physical access audit logs for [Assignment: entry or exit points]; c. Control access to areas within the facility designated as publicly accessible by implementing the following controls: [Assignment: physical access controls]; d. Escort visitors and control visitor activity [Assignment: circumstances]; e. Secure keys, combinations, and other physical access devices; f. Inventory [Assignment: physical access devices] every [Assignment: frequency] ; and g. Change combinations and keys [Assignment: organization-defined frequency] and/or when keys are lost, combinations are compromised, or when individuals possessing the keys or combinations are transferred or terminated.

Discussion

Physical access control applies to employees and visitors. Individuals with permanent physical access authorizations are not considered visitors. Physical access controls for publicly accessible areas may include physical access control logs/records, guards, or physical access devices and barriers to prevent movement from publicly accessible areas to non-public areas. Organizations determine the types of guards needed, including professional security staff, system users, or administrative staff. Physical access devices include keys, locks, combinations, biometric readers, and card readers. Physical access control systems comply with applicable laws, executive orders, directives, policies, regulations, standards, and guidelines. Organizations have flexibility in the types of audit logs employed. Audit logs can be procedural, automated, or some combination thereof. Physical access points can include facility access points, interior access points to systems that require supplemental access controls, or both. Components of systems may be in areas designated as publicly accessible with organizations controlling access to the components.

NIST control statement

Enforce physical access authorizations to the system in addition to the physical access controls for the facility at [Assignment: physical spaces].

Discussion

Control of physical access to the system provides additional physical security for those areas within facilities where there is a concentration of system components.

NIST control statement

Perform security checks [Assignment: frequency] at the physical perimeter of the facility or system for exfiltration of information or removal of system components.

Discussion

Organizations determine the extent, frequency, and/or randomness of security checks to adequately mitigate risk associated with exfiltration.

NIST control statement

Employ guards to control [Assignment: physical access points] to the facility where the system resides 24 hours per day, 7 days per week.

Discussion

Employing guards at selected physical access points to the facility provides a more rapid response capability for organizations. Guards also provide the opportunity for human surveillance in areas of the facility not covered by video surveillance.

NIST control statement

Use lockable physical casings to protect [Assignment: system components] from unauthorized physical access.

Discussion

The greatest risk from the use of portable devices—such as smart phones, tablets, and notebook computers—is theft. Organizations can employ lockable, physical casings to reduce or eliminate the risk of equipment theft. Such casings come in a variety of sizes, from units that protect a single notebook computer to full cabinets that can protect multiple servers, computers, and peripherals. Lockable physical casings can be used in conjunction with cable locks or lockdown plates to prevent the theft of the locked casing containing the computer equipment.

NIST control statement

Employ [Assignment: anti-tamper technologies] to [Selection (one-or-more): detect; prevent] physical tampering or alteration of [Assignment: hardware components] within the system.

Discussion

Organizations can implement tamper detection and prevention at selected hardware components or implement tamper detection at some components and tamper prevention at other components. Detection and prevention activities can employ many types of anti-tamper technologies, including tamper-detection seals and anti-tamper coatings. Anti-tamper programs help to detect hardware alterations through counterfeiting and other supply chain-related risks.

NIST control statement

Withdrawn in this source release; review the official source for disposition.

NIST control statement

Limit access using physical barriers.

Discussion

Physical barriers include bollards, concrete slabs, jersey walls, and hydraulic active vehicle barriers.

NIST control statement

Employ access control vestibules at [Assignment: locations].

Discussion

An access control vestibule is part of a physical access control system that typically provides a space between two sets of interlocking doors. Vestibules are designed to prevent unauthorized individuals from following authorized individuals into facilities with controlled access. This activity, also known as piggybacking or tailgating, results in unauthorized access to the facility. Interlocking door controllers can be used to limit the number of individuals who enter controlled access points and to provide containment areas while authorization for physical access is verified. Interlocking door controllers can be fully automated (i.e., controlling the opening and closing of the doors) or partially automated (i.e., using security guards to control the number of individuals entering the containment area).

NIST control statement

Develop an organization-wide continuous monitoring strategy and implement continuous monitoring programs that include: a. Establishing the following organization-wide metrics to be monitored: [Assignment: metrics]; b. Establishing [Assignment: monitoring frequencies] and [Assignment: assessment frequencies] for control effectiveness; c. Ongoing monitoring of organizationally-defined metrics in accordance with the continuous monitoring strategy; d. Correlation and analysis of information generated by control assessments and monitoring; e. Response actions to address results of the analysis of control assessment and monitoring information; and f. Reporting the security and privacy status of organizational systems to [Assignment: organization-defined personnel or roles] [Assignment: organization-defined frequency].

Discussion

Continuous monitoring at the organization level facilitates ongoing awareness of the security and privacy posture across the organization to support organizational risk management decisions. The terms "continuous" and "ongoing" imply that organizations assess and monitor their controls and risks at a frequency sufficient to support risk-based decisions. Different types of controls may require different monitoring frequencies. The results of continuous monitoring guide and inform risk response actions by organizations. Continuous monitoring programs allow organizations to maintain the authorizations of systems and common controls in highly dynamic environments of operation with changing mission and business needs, threats, vulnerabilities, and technologies. Having access to security- and privacy-related information on a continuing basis through reports and dashboards gives organizational officials the capability to make effective, timely, and informed risk management decisions, including ongoing authorization decisions. To further facilitate security and privacy risk management, organizations consider aligning organization-defined monitoring metrics with organizational risk tolerance as defined in the risk management strategy. Monitoring requirements, including the need for monitoring, may be referenced in other controls and control enhancements such as, [AC-2g](#ac-2_smt.g), [AC-2(7)](#ac-2.7), [AC-2(12)(a)](#ac-2.12_smt.a), [AC-2(7)(b)](#ac-2.7_smt.b), [AC-2(7)(c)](#ac-2.7_smt.c), [AC-17(1)](#ac-17.1), [AT-4a](#at-4_smt.a), [AU-13](#au-13), [AU-13(1)](#au-13.1), [AU-13(2)](#au-13.2), [CA-7](#ca-7), [CM-3f](#cm-3_smt.f), [CM-6d](#cm-6_smt.d), [CM-11c](#cm-11_smt.c), [IR-5](#ir-5), [MA-2b](#ma-2_smt.b), [MA-3a](#ma-3_smt.a), [MA-4a](#ma-4_smt.a), [PE-3d](#pe-3_smt.d), [PE-6](#pe-6), [PE-14b](#pe-14_smt.b), [PE-16](#pe-16), [PE-20](#pe-20), [PM-6](#pm-6), [PM-23](#pm-23), [PS-7e](#ps-7_smt.e), [SA-9c](#sa-9_smt.c), [SC-5(3)(b)](#sc-5.3_smt.b), [SC-7a](#sc-7_smt.a), [SC-7(24)(b)](#sc-7.24_smt.b), [SC-18b](#sc-18_smt.b), [SC-43b](#sc-43_smt.b), [SI-4](#si-4).