NIST SP 800-53 Rev. 5 Common Control Library

NIST control statement

Centrally manage [Assignment: controls and related processes].

Discussion

Central management refers to organization-wide management and implementation of selected controls and processes. This includes planning, implementing, assessing, authorizing, and monitoring the organization-defined, centrally managed controls and processes. As the central management of controls is generally associated with the concept of common (inherited) controls, such management promotes and facilitates standardization of control implementations and management and the judicious use of organizational resources. Centrally managed controls and processes may also meet independence requirements for assessments in support of initial and ongoing authorizations to operate and as part of organizational continuous monitoring. Automated tools (e.g., security information and event management tools or enterprise security monitoring and management tools) can improve the accuracy, consistency, and availability of information associated with centrally managed controls and processes. Automation can also provide data aggregation and data correlation capabilities; alerting mechanisms; and dashboards to support risk-based decision-making within the organization. As part of the control selection processes, organizations determine the controls that may be suitable for central management based on resources and capabilities. It is not always possible to centrally manage every aspect of a control. In such cases, the control can be treated as a hybrid control with the control managed and implemented centrally or at the system level. The controls and control enhancements that are candidates for full or partial central management include but are not limited to: [AC-2(1)](#ac-2.1), [AC-2(2)](#ac-2.2), [AC-2(3)](#ac-2.3), [AC-2(4)](#ac-2.4), [AC-4(all)](#ac-4), [AC-17(1)](#ac-17.1), [AC-17(2)](#ac-17.2), [AC-17(3)](#ac-17.3), [AC-17(9)](#ac-17.9), [AC-18(1)](#ac-18.1), [AC-18(3)](#ac-18.3), [AC-18(4)](#ac-18.4), [AC-18(5)](#ac-18.5), [AC-19(4)](#ac-19.4), [AC-22](#ac-22), [AC-23](#ac-23), [AT-2(1)](#at-2.1), [AT-2(2)](#at-2.2), [AT-3(1)](#at-3.1), [AT-3(2)](#at-3.2), [AT-3(3)](#at-3.3), [AT-4](#at-4), [AU-3](#au-3), [AU-6(1)](#au-6.1), [AU-6(3)](#au-6.3), [AU-6(5)](#au-6.5), [AU-6(6)](#au-6.6), [AU-6(9)](#au-6.9), [AU-7(1)](#au-7.1), [AU-7(2)](#au-7.2), [AU-11](#au-11), [AU-13](#au-13), [AU-16](#au-16), [CA-2(1)](#ca-2.1), [CA-2(2)](#ca-2.2), [CA-2(3)](#ca-2.3), [CA-3(1)](#ca-3.1), [CA-3(2)](#ca-3.2), [CA-3(3)](#ca-3.3), [CA-7(1)](#ca-7.1), [CA-9](#ca-9), [CM-2(2)](#cm-2.2), [CM-3(1)](#cm-3.1), [CM-3(4)](#cm-3.4), [CM-4](#cm-4), [CM-6](#cm-6), [CM-6(1)](#cm-6.1), [CM-7(2)](#cm-7.2), [CM-7(4)](#cm-7.4), [CM-7(5)](#cm-7.5), [CM-8(all)](#cm-8), [CM-9(1)](#cm-9.1), [CM-10](#cm-10), [CM-11](#cm-11), [CP-7(all)](#cp-7), [CP-8(all)](#cp-8), [SC-43](#sc-43), [SI-2](#si-2), [SI-3](#si-3), [SI-4(all)](#si-4), [SI-7](#si-7), [SI-8](#si-8).

NIST control statement

a. Identify, report, and correct system flaws; b. Test software and firmware updates related to flaw remediation for effectiveness and potential side effects before installation; c. Install security-relevant software and firmware updates within [Assignment: time period] of the release of the updates; and d. Incorporate flaw remediation into the organizational configuration management process.

Discussion

The need to remediate system flaws applies to all types of software and firmware. Organizations identify systems affected by software flaws, including potential vulnerabilities resulting from those flaws, and report this information to designated organizational personnel with information security and privacy responsibilities. Security-relevant updates include patches, service packs, and malicious code signatures. Organizations also address flaws discovered during assessments, continuous monitoring, incident response activities, and system error handling. By incorporating flaw remediation into configuration management processes, required remediation actions can be tracked and verified. Organization-defined time periods for updating security-relevant software and firmware may vary based on a variety of risk factors, including the security category of the system, the criticality of the update (i.e., severity of the vulnerability related to the discovered flaw), the organizational risk tolerance, the mission supported by the system, or the threat environment. Some types of flaw remediation may require more testing than other types. Organizations determine the type of testing needed for the specific type of flaw remediation activity under consideration and the types of changes that are to be configuration-managed. In some situations, organizations may determine that the testing of software or firmware updates is not necessary or practical, such as when implementing simple malicious code signature updates. In testing decisions, organizations consider whether security-relevant software or firmware updates are obtained from authorized sources with appropriate digital signatures.

NIST control statement

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

NIST control statement

Determine if system components have applicable security-relevant software and firmware updates installed using [Assignment: automated mechanisms] [Assignment: frequency].

Discussion

Automated mechanisms can track and determine the status of known flaws for system components.

NIST control statement

(a) Measure the time between flaw identification and flaw remediation; and (b) Establish the following benchmarks for taking corrective actions: [Assignment: benchmarks].

Discussion

Organizations determine the time it takes on average to correct system flaws after such flaws have been identified and subsequently establish organizational benchmarks (i.e., time frames) for taking corrective actions. Benchmarks can be established by the type of flaw or the severity of the potential vulnerability if the flaw can be exploited.

NIST control statement

Employ automated patch management tools to facilitate flaw remediation to the following system components: [Assignment: components].

Discussion

Using automated tools to support patch management helps to ensure the timeliness and completeness of system patching operations.

NIST control statement

Install [Assignment: security-relevant software and firmware updates] automatically to [Assignment: system components].

Discussion

Due to system integrity and availability concerns, organizations consider the methodology used to carry out automatic updates. Organizations balance the need to ensure that the updates are installed as soon as possible with the need to maintain configuration management and control with any mission or operational impacts that automatic updates might impose.

NIST control statement

Remove previous versions of [Assignment: software and firmware components] after updated versions have been installed.

Discussion

Previous versions of software or firmware components that are not removed from the system after updates have been installed may be exploited by adversaries. Some products may automatically remove previous versions of software and firmware from the system.

NIST control statement

Embed data or capabilities in the following systems or system components to determine if organizational data has been exfiltrated or improperly removed from the organization: [Assignment: systems or system components].

Discussion

Many cyber-attacks target organizational information, or information that the organization holds on behalf of other entities (e.g., personally identifiable information), and exfiltrate that data. In addition, insider attacks and erroneous user procedures can remove information from the system that is in violation of the organizational policies. Tainting approaches can range from passive to active. A passive tainting approach can be as simple as adding false email names and addresses to an internal database. If the organization receives email at one of the false email addresses, it knows that the database has been compromised. Moreover, the organization knows that the email was sent by an unauthorized entity, so any packets it includes potentially contain malicious code, and that the unauthorized entity may have potentially obtained a copy of the database. Another tainting approach can include embedding false data or steganographic data in files to enable the data to be found via open-source analysis. Finally, an active tainting approach can include embedding software in the data that is able to "call home," thereby alerting the organization to its "capture," and possibly its location, and the path by which it was exfiltrated or removed.

NIST control statement

Refresh [Assignment: information] at [Assignment: frequencies] or generate the information on demand and delete the information when no longer needed.

Discussion

Retaining information for longer than it is needed makes it an increasingly valuable and enticing target for adversaries. Keeping information available for the minimum period of time needed to support organizational missions or business functions reduces the opportunity for adversaries to compromise, capture, and exfiltrate that information.

NIST control statement

a. Identify the following alternative sources of information for [Assignment: essential functions and services]: [Assignment: alternative information sources] ; and b. Use an alternative information source for the execution of essential functions or services on [Assignment: systems or system components] when the primary source of information is corrupted or unavailable.

Discussion

Actions taken by a system service or a function are often driven by the information it receives. Corruption, fabrication, modification, or deletion of that information could impact the ability of the service function to properly carry out its intended actions. By having multiple sources of input, the service or function can continue operation if one source is corrupted or no longer available. It is possible that the alternative sources of information may be less precise or less accurate than the primary source of information. But having such sub-optimal information sources may still provide a sufficient level of quality that the essential service or function can be carried out, even in a degraded or debilitated manner.

NIST control statement

Based on [Assignment: circumstances]: a. Fragment the following information: [Assignment: information] ; and b. Distribute the fragmented information across the following systems or system components: [Assignment: systems or system components].

Discussion

One objective of the advanced persistent threat is to exfiltrate valuable information. Once exfiltrated, there is generally no way for the organization to recover the lost information. Therefore, organizations may consider dividing the information into disparate elements and distributing those elements across multiple systems or system components and locations. Such actions will increase the adversary’s work factor to capture and exfiltrate the desired information and, in so doing, increase the probability of detection. The fragmentation of information impacts the organization’s ability to access the information in a timely manner. The extent of the fragmentation is dictated by the impact or classification level (and value) of the information, threat intelligence information received, and whether data tainting is used (i.e., data tainting-derived information about the exfiltration of some information could result in the fragmentation of the remaining information).