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

a. Approve and monitor nonlocal maintenance and diagnostic activities; b. Allow the use of nonlocal maintenance and diagnostic tools only as consistent with organizational policy and documented in the security plan for the system; c. Employ strong authentication in the establishment of nonlocal maintenance and diagnostic sessions; d. Maintain records for nonlocal maintenance and diagnostic activities; and e. Terminate session and network connections when nonlocal maintenance is completed.

Discussion

Nonlocal maintenance and diagnostic activities are conducted by individuals who communicate through either an external or internal network. Local maintenance and diagnostic activities are carried out by individuals who are physically present at the system location and not communicating across a network connection. Authentication techniques used to establish nonlocal maintenance and diagnostic sessions reflect the network access requirements in [IA-2](#ia-2) . Strong authentication requires authenticators that are resistant to replay attacks and employ multi-factor authentication. Strong authenticators include PKI where certificates are stored on a token protected by a password, passphrase, or biometric. Enforcing requirements in [MA-4](#ma-4) is accomplished, in part, by other controls. [SP 800-63B](#e59c5a7c-8b1f-49ca-8de0-6ee0882180ce) provides additional guidance on strong authentication and authenticators.

NIST control statement

(a) Log [Assignment: organization-defined audit events] for nonlocal maintenance and diagnostic sessions; and (b) Review the audit records of the maintenance and diagnostic sessions to detect anomalous behavior.

Discussion

Audit logging for nonlocal maintenance is enforced by [AU-2](#au-2) . Audit events are defined in [AU-2a](#au-2_smt.a).

NIST control statement

Withdrawn in this source release; review the official source for disposition.

NIST control statement

(a) Require that nonlocal maintenance and diagnostic services be performed from a system that implements a security capability comparable to the capability implemented on the system being serviced; or (b) Remove the component to be serviced from the system prior to nonlocal maintenance or diagnostic services; sanitize the component (for organizational information); and after the service is performed, inspect and sanitize the component (for potentially malicious software) before reconnecting the component to the system.

Discussion

Comparable security capability on systems, diagnostic tools, and equipment providing maintenance services implies that the implemented controls on those systems, tools, and equipment are at least as comprehensive as the controls on the system being serviced.

NIST control statement

Protect nonlocal maintenance sessions by: (a) Employing [Assignment: authenticators that are replay resistant] ; and (b) Separating the maintenance sessions from other network sessions with the system by either: (1) Physically separated communications paths; or (2) Logically separated communications paths.

Discussion

Communications paths can be logically separated using encryption.

NIST control statement

(a) Require the approval of each nonlocal maintenance session by [Assignment: personnel or roles] ; and (b) Notify the following personnel or roles of the date and time of planned nonlocal maintenance: [Assignment: personnel and roles].

Discussion

Notification may be performed by maintenance personnel. Approval of nonlocal maintenance is accomplished by personnel with sufficient information security and system knowledge to determine the appropriateness of the proposed maintenance.

NIST control statement

Implement the following cryptographic mechanisms to protect the integrity and confidentiality of nonlocal maintenance and diagnostic communications: [Assignment: cryptographic mechanisms].

Discussion

Failure to protect nonlocal maintenance and diagnostic communications can result in unauthorized individuals gaining access to organizational information. Unauthorized access during remote maintenance sessions can result in a variety of hostile actions, including malicious code insertion, unauthorized changes to system parameters, and exfiltration of organizational information. Such actions can result in the loss or degradation of mission or business capabilities.

NIST control statement

Verify session and network connection termination after the completion of nonlocal maintenance and diagnostic sessions.

Discussion

Verifying the termination of a connection once maintenance is completed ensures that connections established during nonlocal maintenance and diagnostic sessions have been terminated and are no longer available for use.

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).

NIST control statement

a. Monitor the system to detect: 1. Attacks and indicators of potential attacks in accordance with the following monitoring objectives: [Assignment: monitoring objectives] ; and 2. Unauthorized local, network, and remote connections; b. Identify unauthorized use of the system through the following techniques and methods: [Assignment: techniques and methods]; c. Invoke internal monitoring capabilities or deploy monitoring devices: 1. Strategically within the system to collect organization-determined essential information; and 2. At ad hoc locations within the system to track specific types of transactions of interest to the organization; d. Analyze detected events and anomalies; e. Adjust the level of system monitoring activity when there is a change in risk to organizational operations and assets, individuals, other organizations, or the Nation; f. Obtain legal opinion regarding system monitoring activities; and g. Provide [Assignment: system monitoring information] to [Assignment: personnel or roles] [Selection (one-or-more): as needed; [Assignment: frequency] ].

Discussion

System monitoring includes external and internal monitoring. External monitoring includes the observation of events occurring at external interfaces to the system. Internal monitoring includes the observation of events occurring within the system. Organizations monitor systems by observing audit activities in real time or by observing other system aspects such as access patterns, characteristics of access, and other actions. The monitoring objectives guide and inform the determination of the events. System monitoring capabilities are achieved through a variety of tools and techniques, including intrusion detection and prevention systems, malicious code protection software, scanning tools, audit record monitoring software, and network monitoring software. Depending on the security architecture, the distribution and configuration of monitoring devices may impact throughput at key internal and external boundaries as well as at other locations across a network due to the introduction of network throughput latency. If throughput management is needed, such devices are strategically located and deployed as part of an established organization-wide security architecture. Strategic locations for monitoring devices include selected perimeter locations and near key servers and server farms that support critical applications. Monitoring devices are typically employed at the managed interfaces associated with controls [SC-7](#sc-7) and [AC-17](#ac-17) . The information collected is a function of the organizational monitoring objectives and the capability of systems to support such objectives. Specific types of transactions of interest include Hypertext Transfer Protocol (HTTP) traffic that bypasses HTTP proxies. System monitoring is an integral part of organizational continuous monitoring and incident response programs, and output from system monitoring serves as input to those programs. System monitoring requirements, including the need for specific types of system monitoring, may be referenced in other controls (e.g., [AC-2g](#ac-2_smt.g), [AC-2(7)](#ac-2.7), [AC-2(12)(a)](#ac-2.12_smt.a), [AC-17(1)](#ac-17.1), [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), [MA-3a](#ma-3_smt.a), [MA-4a](#ma-4_smt.a), [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) ). Adjustments to levels of system monitoring are based on law enforcement information, intelligence information, or other sources of information. The legality of system monitoring activities is based on applicable laws, executive orders, directives, regulations, policies, standards, and guidelines.

NIST control statement

Manage and retain information within the system and information output from the system in accordance with applicable laws, executive orders, directives, regulations, policies, standards, guidelines and operational requirements.

Discussion

Information management and retention requirements cover the full life cycle of information, in some cases extending beyond system disposal. Information to be retained may also include policies, procedures, plans, reports, data output from control implementation, and other types of administrative information. The National Archives and Records Administration (NARA) provides federal policy and guidance on records retention and schedules. If organizations have a records management office, consider coordinating with records management personnel. Records produced from the output of implemented controls that may require management and retention include, but are not limited to: All XX-1, [AC-6(9)](#ac-6.9), [AT-4](#at-4), [AU-12](#au-12), [CA-2](#ca-2), [CA-3](#ca-3), [CA-5](#ca-5), [CA-6](#ca-6), [CA-7](#ca-7), [CA-8](#ca-8), [CA-9](#ca-9), [CM-2](#cm-2), [CM-3](#cm-3), [CM-4](#cm-4), [CM-6](#cm-6), [CM-8](#cm-8), [CM-9](#cm-9), [CM-12](#cm-12), [CM-13](#cm-13), [CP-2](#cp-2), [IR-6](#ir-6), [IR-8](#ir-8), [MA-2](#ma-2), [MA-4](#ma-4), [PE-2](#pe-2), [PE-8](#pe-8), [PE-16](#pe-16), [PE-17](#pe-17), [PL-2](#pl-2), [PL-4](#pl-4), [PL-7](#pl-7), [PL-8](#pl-8), [PM-5](#pm-5), [PM-8](#pm-8), [PM-9](#pm-9), [PM-18](#pm-18), [PM-21](#pm-21), [PM-27](#pm-27), [PM-28](#pm-28), [PM-30](#pm-30), [PM-31](#pm-31), [PS-2](#ps-2), [PS-6](#ps-6), [PS-7](#ps-7), [PT-2](#pt-2), [PT-3](#pt-3), [PT-7](#pt-7), [RA-2](#ra-2), [RA-3](#ra-3), [RA-5](#ra-5), [RA-8](#ra-8), [SA-4](#sa-4), [SA-5](#sa-5), [SA-8](#sa-8), [SA-10](#sa-10), [SI-4](#si-4), [SR-2](#sr-2), [SR-4](#sr-4), [SR-8](#sr-8).