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What is AC-17 Remote Access? | Remote access is access to organizational systems (or processes acting on behalf of users) that communicate through external networks such as the Internet. Types of remote access include dial-up, broadband, and wireless. Organizations use encrypted virtual private networks (VPNs) to enhance confidentiality and integrity for remote connections. The use of encrypted VPNs provides sufficient assurance to the organization that it can effectively treat such connections as internal networks if the cryptographic mechanisms used are implemented in accordance with applicable laws, executive orders, directives, regulations, policies, standards, and guidelines. Still, VPN connections traverse external networks, and the encrypted VPN does not enhance the availability of remote connections. VPNs with encrypted tunnels can also affect the ability to adequately monitor network communications traffic for malicious code. Remote access controls apply to systems other than public web servers or systems designed for public access. Authorization of each remote access type addresses authorization prior to allowing remote access without specifying the specific formats for such authorization. While organizations may use information exchange and system connection security agreements to manage remote access connections to other systems, such agreements are addressed as part of CA-3. Enforcing access restrictions for remote access is addressed via AC-3. |
What is AC-17(1) Remote Access | Monitoring and Control? | Monitoring and control of remote access methods allows organizations to detect attacks and help ensure compliance with remote access policies by auditing the connection activities of remote users on a variety of system components, including servers, notebook computers, workstations, smart phones, and tablets. Audit logging for remote access is enforced by AU-2. Audit events are defined in AU-2a. |
What is AC-17(2) Remote Access | Protection of Confidentiality and Integrity Using Encryption? | Virtual private networks can be used to protect the confidentiality and integrity of remote access sessions. Transport Layer Security (TLS) is an example of a cryptographic protocol that provides end-to-end communications security over networks and is used for Internet communications and online transactions. |
What is AC-17(3) Remote Access | Managed Access Control Points? | Organizations consider the Trusted Internet Connections (TIC) initiative DHS TIC requirements for external network connections since limiting the number of access control points for remote access reduces attack surfaces. |
What is AC-17(4) Remote Access | Privileged Commands and Access? | Remote access to systems represents a significant potential vulnerability that can be exploited by adversaries. As such, restricting the execution of privileged commands and access to security-relevant information via remote access reduces the exposure of the organization and the susceptibility to threats by adversaries to the remote access capability. |
What is AC-17(6) Remote Access | Protection of Mechanism Information? | Remote access to organizational information by non-organizational entities can increase the risk of unauthorized use and disclosure about remote access mechanisms. The organization considers including remote access requirements in the information exchange agreements with other organizations, as applicable. Remote access requirements can also be included in rules of behavior (see PL-4) and access agreements (see PS-6). |
What is AC-17(9) Remote Access | Disconnect or Disable Access? | The speed of system disconnect or disablement varies based on the criticality of missions or business functions and the need to eliminate immediate or future remote access to systems. |
What is AC-17(10) Remote Access | Authenticate Remote Commands? | Authenticating remote commands protects against unauthorized commands and the replay of authorized commands. The ability to authenticate remote commands is important for remote systems for which loss, malfunction, misdirection, or exploitation would have immediate or serious consequences, such as injury, death, property damage, loss of high value assets, failure of mission or business functions, or compromise of classified or controlled unclassified information. Authentication mechanisms for remote commands ensure that systems accept and execute commands in the order intended, execute only authorized commands, and reject unauthorized commands. Cryptographic mechanisms can be used, for example, to authenticate remote commands. |
What is AC-18 Wireless Access? | Wireless technologies include microwave, packet radio (ultra-high frequency or very high frequency), 802.11x, and Bluetooth. Wireless networks use authentication protocols that provide authenticator protection and mutual authentication. |
What is AC-18(1) Wireless Access | Authentication and Encryption? | Wireless networking capabilities represent a significant potential vulnerability that can be exploited by adversaries. To protect systems with wireless access points, strong authentication of users and devices along with strong encryption can reduce susceptibility to threats by adversaries involving wireless technologies. |
What is AC-18(3) Wireless Access | Disable Wireless Networking? | Wireless networking capabilities that are embedded within system components represent a significant potential vulnerability that can be exploited by adversaries. Disabling wireless capabilities when not needed for essential organizational missions or functions can reduce susceptibility to threats by adversaries involving wireless technologies. |
What is AC-18(4) Wireless Access | Restrict Configurations by Users? | Organizational authorizations to allow selected users to configure wireless networking capabilities are enforced, in part, by the access enforcement mechanisms employed within organizational systems. |
What is AC-18(5) Wireless Access | Antennas and Transmission Power Levels? | Actions that may be taken to limit unauthorized use of wireless communications outside of organization-controlled boundaries include reducing the power of wireless transmissions so that the transmissions are less likely to emit a signal that can be captured outside of the physical perimeters of the organization, employing measures such as emissions security to control wireless emanations, and using directional or beamforming antennas that reduce the likelihood that unintended receivers will be able to intercept signals. Prior to taking such mitigating actions, organizations can conduct periodic wireless surveys to understand the radio frequency profile of organizational systems as well as other systems that may be operating in the area. |
What is AC-19 Access Control for Mobile Devices? | A mobile device is a computing device that has a small form factor such that it can easily be carried by a single individual; is designed to operate without a physical connection; possesses local, non-removable or removable data storage; and includes a self-contained power source. Mobile device functionality may also include voice communication capabilities, on-board sensors that allow the device to capture information, and/or built-in features for synchronizing local data with remote locations. Examples include smart phones and tablets. Mobile devices are typically associated with a single individual. The processing, storage, and transmission capability of the mobile device may be comparable to or merely a subset of notebook/desktop systems, depending on the nature and intended purpose of the device. Protection and control of mobile devices is behavior or policy-based and requires users to take physical action to protect and control such devices when outside of controlled areas. Controlled areas are spaces for which organizations provide physical or procedural controls to meet the requirements established for protecting information and systems.
Due to the large variety of mobile devices with different characteristics and capabilities, organizational restrictions may vary for the different classes or types of such devices. Usage restrictions and specific implementation guidance for mobile devices include configuration management, device identification and authentication, implementation of mandatory protective software, scanning devices for malicious code, updating virus protection software, scanning for critical software updates and patches, conducting primary operating system (and possibly other resident software) integrity checks, and disabling unnecessary hardware.
Usage restrictions and authorization to connect may vary among organizational systems. For example, the organization may authorize the connection of mobile devices to its network and impose a set of usage restrictions, while a system owner may withhold authorization for mobile device connection to specific applications or impose additional usage restrictions before allowing mobile device connections to a system. Adequate security for mobile devices goes beyond the requirements specified in AC-19. Many safeguards for mobile devices are reflected in other controls. AC-20 addresses mobile devices that are not organization-controlled. |
What is AC-19(4) Access Control for Mobile Devices | Restrictions for Classified Information? | None. |
What is AC-19(5) Access Control for Mobile Devices | Full Device or Container-based Encryption? | Container-based encryption provides a more fine-grained approach to data and information encryption on mobile devices, including encrypting selected data structures such as files, records, or fields. |
What is AC-20 Use of External Systems? | External systems are systems that are used by but not part of organizational systems, and for which the organization has no direct control over the implementation of required controls or the assessment of control effectiveness. External systems include personally owned systems, components, or devices; privately owned computing and communications devices in commercial or public facilities; systems owned or controlled by nonfederal organizations; systems managed by contractors; and federal information systems that are not owned by, operated by, or under the direct supervision or authority of the organization. External systems also include systems owned or operated by other components within the same organization and systems within the organization with different authorization boundaries. Organizations have the option to prohibit the use of any type of external system or prohibit the use of specified types of external systems, (e.g., prohibit the use of any external system that is not organizationally owned or prohibit the use of personally-owned systems).
For some external systems (i.e., systems operated by other organizations), the trust relationships that have been established between those organizations and the originating organization may be such that no explicit terms and conditions are required. Systems within these organizations may not be considered external. These situations occur when, for example, there are pre-existing information exchange agreements (either implicit or explicit) established between organizations or components or when such agreements are specified by applicable laws, executive orders, directives, regulations, policies, or standards. Authorized individuals include organizational personnel, contractors, or other individuals with authorized access to organizational systems and over which organizations have the authority to impose specific rules of behavior regarding system access. Restrictions that organizations impose on authorized individuals need not be uniform, as the restrictions may vary depending on trust relationships between organizations. Therefore, organizations may choose to impose different security restrictions on contractors than on state, local, or tribal governments.
External systems used to access public interfaces to organizational systems are outside the scope of AC-20. Organizations establish specific terms and conditions for the use of external systems in accordance with organizational security policies and procedures. At a minimum, terms and conditions address the specific types of applications that can be accessed on organizational systems from external systems and the highest security category of information that can be processed, stored, or transmitted on external systems. If the terms and conditions with the owners of the external systems cannot be established, organizations may impose restrictions on organizational personnel using those external systems. |
What is AC-20(1) Use of External Systems | Limits on Authorized Use? | Limiting authorized use recognizes circumstances where individuals using external systems may need to access organizational systems. Organizations need assurance that the external systems contain the necessary controls so as not to compromise, damage, or otherwise harm organizational systems. Verification that the required controls have been implemented can be achieved by external, independent assessments, attestations, or other means, depending on the confidence level required by organizations. |
What is AC-20(2) Use of External Systems | Portable Storage Devices — Restricted Use? | Limits on the use of organization-controlled portable storage devices in external systems include restrictions on how the devices may be used and under what conditions the devices may be used. |
What is AC-20(3) Use of External Systems | Non-organizationally Owned Systems — Restricted Use? | Non-organizationally owned systems or system components include systems or system components owned by other organizations as well as personally owned devices. There are potential risks to using non-organizationally owned systems or components. In some cases, the risk is sufficiently high as to prohibit such use (see AC-20 b.). In other cases, the use of such systems or system components may be allowed but restricted in some way. Restrictions include requiring the implementation of approved controls prior to authorizing the connection of non-organizationally owned systems and components; limiting access to types of information, services, or applications; using virtualization techniques to limit processing and storage activities to servers or system components provisioned by the organization; and agreeing to the terms and conditions for usage. Organizations consult with the Office of the General Counsel regarding legal issues associated with using personally owned devices, including requirements for conducting forensic analyses during investigations after an incident. |
What is AC-20(4) Use of External Systems | Network Accessible Storage Devices — Prohibited Use? | Network-accessible storage devices in external systems include online storage devices in public, hybrid, or community cloud-based systems. |
What is AC-20(5) Use of External Systems | Portable Storage Devices — Prohibited Use? | Limits on the use of organization-controlled portable storage devices in external systems include a complete prohibition of the use of such devices. Prohibiting such use is enforced using technical methods and/or nontechnical (i.e., process-based) methods. |
What is AC-21 Information Sharing? | Information sharing applies to information that may be restricted in some manner based on some formal or administrative determination. Examples of such information include, contract-sensitive information, classified information related to special access programs or compartments, privileged information, proprietary information, and personally identifiable information. Security and privacy risk assessments as well as applicable laws, regulations, and policies can provide useful inputs to these determinations. Depending on the circumstances, sharing partners may be defined at the individual, group, or organizational level. Information may be defined by content, type, security category, or special access program or compartment. Access restrictions may include non-disclosure agreements (NDA). Information flow techniques and security attributes may be used to provide automated assistance to users making sharing and collaboration decisions. |
What is AC-21(1) Information Sharing | Automated Decision Support? | Automated mechanisms are used to enforce information sharing decisions. |
What is AC-21(2) Information Sharing | Information Search and Retrieval? | Information search and retrieval services identify information system resources relevant to an information need. |
What is AC-22 Publicly Accessible Content? | In accordance with applicable laws, executive orders, directives, policies, regulations, standards, and guidelines, the public is not authorized to have access to nonpublic information, including information protected under the PRIVACT and proprietary information. Publicly accessible content addresses systems that are controlled by the organization and accessible to the public, typically without identification or authentication. Posting information on non-organizational systems (e.g., non-organizational public websites, forums, and social media) is covered by organizational policy. While organizations may have individuals who are responsible for developing and implementing policies about the information that can be made publicly accessible, publicly accessible content addresses the management of the individuals who make such information publicly accessible. |
What is AC-23 Data Mining Protection? | Data mining is an analytical process that attempts to find correlations or patterns in large data sets for the purpose of data or knowledge discovery. Data storage objects include database records and database fields. Sensitive information can be extracted from data mining operations. When information is personally identifiable information, it may lead to unanticipated revelations about individuals and give rise to privacy risks. Prior to performing data mining activities, organizations determine whether such activities are authorized. Organizations may be subject to applicable laws, executive orders, directives, regulations, or policies that address data mining requirements. Organizational personnel consult with the senior agency official for privacy and legal counsel regarding such requirements.
Data mining prevention and detection techniques include limiting the number and frequency of database queries to increase the work factor needed to determine the contents of databases, limiting types of responses provided to database queries, applying differential privacy techniques or homomorphic encryption, and notifying personnel when atypical database queries or accesses occur. Data mining protection focuses on protecting information from data mining while such information resides in organizational data stores. In contrast, AU-13 focuses on monitoring for organizational information that may have been mined or otherwise obtained from data stores and is available as open-source information residing on external sites, such as social networking or social media websites.
EO 13587 requires the establishment of an insider threat program for deterring, detecting, and mitigating insider threats, including the safeguarding of sensitive information from exploitation, compromise, or other unauthorized disclosure. Data mining protection requires organizations to identify appropriate techniques to prevent and detect unnecessary or unauthorized data mining. Data mining can be used by an insider to collect organizational information for the purpose of exfiltration. |
What is AC-24 Access Control Decisions? | Access control decisions (also known as authorization decisions) occur when authorization information is applied to specific accesses. In contrast, access enforcement occurs when systems enforce access control decisions. While it is common to have access control decisions and access enforcement implemented by the same entity, it is not required, and it is not always an optimal implementation choice. For some architectures and distributed systems, different entities may make access control decisions and enforce access. |
What is AC-24(1) Access Control Decisions | Transmit Access Authorization Information? | Authorization processes and access control decisions may occur in separate parts of systems or in separate systems. In such instances, authorization information is transmitted securely (e.g., using cryptographic mechanisms) so that timely access control decisions can be enforced at the appropriate locations. To support the access control decisions, it may be necessary to transmit as part of the access authorization information supporting security and privacy attributes. This is because in distributed systems, there are various access control decisions that need to be made, and different entities make these decisions in a serial fashion, each requiring those attributes to make the decisions. Protecting access authorization information ensures that such information cannot be altered, spoofed, or compromised during transmission. |
What is AC-24(2) Access Control Decisions | No User or Process Identity? | In certain situations, it is important that access control decisions can be made without information regarding the identity of the users issuing the requests. These are generally instances where preserving individual privacy is of paramount importance. In other situations, user identification information is simply not needed for access control decisions, and especially in the case of distributed systems, transmitting such information with the needed degree of assurance may be very expensive or difficult to accomplish. MAC, RBAC, ABAC, and label-based control policies, for example, might not include user identity as an attribute. |
What is AC-25 Reference Monitor? | A reference monitor is a set of design requirements on a reference validation mechanism that, as a key component of an operating system, enforces an access control policy over all subjects and objects. A reference validation mechanism is always invoked, tamper-proof, and small enough to be subject to analysis and tests, the completeness of which can be assured (i.e., verifiable). Information is represented internally within systems using abstractions known as data structures. Internal data structures can represent different types of entities, both active and passive. Active entities, also known as subjects, are associated with individuals, devices, or processes acting on behalf of individuals. Passive entities, also known as objects, are associated with data structures, such as records, buffers, communications ports, tables, files, and inter-process pipes. Reference monitors enforce access control policies that restrict access to objects based on the identity of subjects or groups to which the subjects belong. The system enforces the access control policy based on the rule set established by the policy. The tamper-proof property of the reference monitor prevents determined adversaries from compromising the functioning of the reference validation mechanism. The always invoked property prevents adversaries from bypassing the mechanism and violating the security policy. The smallness property helps to ensure completeness in the analysis and testing of the mechanism to detect any weaknesses or deficiencies (i.e., latent flaws) that would prevent the enforcement of the security policy. |
What is AT-1 Policy and Procedures? | Awareness and training policy and procedures address the controls in the AT family that are implemented within systems and organizations. The risk management strategy is an important factor in establishing such policies and procedures. Policies and procedures contribute to security and privacy assurance. Therefore, it is important that security and privacy programs collaborate on the development of awareness and training policy and procedures. Security and privacy program policies and procedures at the organization level are preferable, in general, and may obviate the need for mission- or system-specific policies and procedures. The policy can be included as part of the general security and privacy policy or be represented by multiple policies that reflect the complex nature of organizations. Procedures can be established for security and privacy programs, for mission or business processes, and for systems, if needed. Procedures describe how the policies or controls are implemented and can be directed at the individual or role that is the object of the procedure. Procedures can be documented in system security and privacy plans or in one or more separate documents. Events that may precipitate an update to awareness and training policy and procedures include assessment or audit findings, security incidents or breaches, or changes in applicable laws, executive orders, directives, regulations, policies, standards, and guidelines. Simply restating controls does not constitute an organizational policy or procedure. |
What is AT-2 Literacy Training and Awareness? | Organizations provide basic and advanced levels of literacy training to system users, including measures to test the knowledge level of users. Organizations determine the content of literacy training and awareness based on specific organizational requirements, the systems to which personnel have authorized access, and work environments (e.g., telework). The content includes an understanding of the need for security and privacy as well as actions by users to maintain security and personal privacy and to respond to suspected incidents. The content addresses the need for operations security and the handling of personally identifiable information.
Awareness techniques include displaying posters, offering supplies inscribed with security and privacy reminders, displaying logon screen messages, generating email advisories or notices from organizational officials, and conducting awareness events. Literacy training after the initial training described in AT-2a.1 is conducted at a minimum frequency consistent with applicable laws, directives, regulations, and policies. Subsequent literacy training may be satisfied by one or more short ad hoc sessions and include topical information on recent attack schemes, changes to organizational security and privacy policies, revised security and privacy expectations, or a subset of topics from the initial training. Updating literacy training and awareness content on a regular basis helps to ensure that the content remains relevant. Events that may precipitate an update to literacy training and awareness content include, but are not limited to, assessment or audit findings, security incidents or breaches, or changes in applicable laws, executive orders, directives, regulations, policies, standards, and guidelines. |
What is AT-2(1) Literacy Training and Awareness | Practical Exercises? | Practical exercises include no-notice social engineering attempts to collect information, gain unauthorized access, or simulate the adverse impact of opening malicious email attachments or invoking, via spear phishing attacks, malicious web links. |
What is AT-2(2) Literacy Training and Awareness | Insider Threat? | Potential indicators and possible precursors of insider threat can include behaviors such as inordinate, long-term job dissatisfaction; attempts to gain access to information not required for job performance; unexplained access to financial resources; bullying or harassment of fellow employees; workplace violence; and other serious violations of policies, procedures, directives, regulations, rules, or practices. Literacy training includes how to communicate the concerns of employees and management regarding potential indicators of insider threat through channels established by the organization and in accordance with established policies and procedures. Organizations may consider tailoring insider threat awareness topics to the role. For example, training for managers may be focused on changes in the behavior of team members, while training for employees may be focused on more general observations. |
What is AT-2(3) Literacy Training and Awareness | Social Engineering and Mining? | Social engineering is an attempt to trick an individual into revealing information or taking an action that can be used to breach, compromise, or otherwise adversely impact a system. Social engineering includes phishing, pretexting, impersonation, baiting, quid pro quo, thread-jacking, social media exploitation, and tailgating. Social mining is an attempt to gather information about the organization that may be used to support future attacks. Literacy training includes information on how to communicate the concerns of employees and management regarding potential and actual instances of social engineering and data mining through organizational channels based on established policies and procedures. |
What is AT-2(4) Literacy Training and Awareness | Suspicious Communications and Anomalous System Behavior? | A well-trained workforce provides another organizational control that can be employed as part of a defense-in-depth strategy to protect against malicious code coming into organizations via email or the web applications. Personnel are trained to look for indications of potentially suspicious email (e.g., receiving an unexpected email, receiving an email containing strange or poor grammar, or receiving an email from an unfamiliar sender that appears to be from a known sponsor or contractor). Personnel are also trained on how to respond to suspicious email or web communications. For this process to work effectively, personnel are trained and made aware of what constitutes suspicious communications. Training personnel on how to recognize anomalous behaviors in systems can provide organizations with early warning for the presence of malicious code. Recognition of anomalous behavior by organizational personnel can supplement malicious code detection and protection tools and systems employed by organizations. |
What is AT-2(5) Literacy Training and Awareness | Advanced Persistent Threat? | An effective way to detect advanced persistent threats (APT) and to preclude successful attacks is to provide specific literacy training for individuals. Threat literacy training includes educating individuals on the various ways that APTs can infiltrate the organization (e.g., through websites, emails, advertisement pop-ups, articles, and social engineering). Effective training includes techniques for recognizing suspicious emails, use of removable systems in non-secure settings, and the potential targeting of individuals at home. |
What is AT-2(6) Literacy Training and Awareness | Cyber Threat Environment? | Since threats continue to change over time, threat literacy training by the organization is dynamic. Moreover, threat literacy training is not performed in isolation from the system operations that support organizational mission and business functions. |
What is AT-3 Role-based Training? | Organizations determine the content of training based on the assigned roles and responsibilities of individuals as well as the security and privacy requirements of organizations and the systems to which personnel have authorized access, including technical training specifically tailored for assigned duties. Roles that may require role-based training include senior leaders or management officials (e.g., head of agency/chief executive officer, chief information officer, senior accountable official for risk management, senior agency information security officer, senior agency official for privacy), system owners; authorizing officials; system security officers; privacy officers; acquisition and procurement officials; enterprise architects; systems engineers; software developers; systems security engineers; privacy engineers; system, network, and database administrators; auditors; personnel conducting configuration management activities; personnel performing verification and validation activities; personnel with access to system-level software; control assessors; personnel with contingency planning and incident response duties; personnel with privacy management responsibilities; and personnel with access to personally identifiable information.
Comprehensive role-based training addresses management, operational, and technical roles and responsibilities covering physical, personnel, and technical controls. Role-based training also includes policies, procedures, tools, methods, and artifacts for the security and privacy roles defined. Organizations provide the training necessary for individuals to fulfill their responsibilities related to operations and supply chain risk management within the context of organizational security and privacy programs. Role-based training also applies to contractors who provide services to federal agencies. Types of training include web-based and computer-based training, classroom-style training, and hands-on training (including micro-training). Updating role-based training on a regular basis helps to ensure that the content remains relevant and effective. Events that may precipitate an update to role-based training content include, but are not limited to, assessment or audit findings, security incidents or breaches, or changes in applicable laws, executive orders, directives, regulations, policies, standards, and guidelines. |
What is AT-3(1) Role-based Training | Environmental Controls? | Environmental controls include fire suppression and detection devices or systems, sprinkler systems, handheld fire extinguishers, fixed fire hoses, smoke detectors, temperature or humidity, heating, ventilation, air conditioning, and power within the facility. |
What is AT-3(2) Role-based Training | Physical Security Controls? | Physical security controls include physical access control devices, physical intrusion and detection alarms, operating procedures for facility security guards, and monitoring or surveillance equipment. |
What is AT-3(3) Role-based Training | Practical Exercises? | Practical exercises for security include training for software developers that addresses simulated attacks that exploit common software vulnerabilities or spear or whale phishing attacks targeted at senior leaders or executives. Practical exercises for privacy include modules with quizzes on identifying and processing personally identifiable information in various scenarios or scenarios on conducting privacy impact assessments. |
What is AT-3(5) Role-based Training | Processing Personally Identifiable Information? | Personally identifiable information processing and transparency controls include the organization’s authority to process personally identifiable information and personally identifiable information processing purposes. Role-based training for federal agencies addresses the types of information that may constitute personally identifiable information and the risks, considerations, and obligations associated with its processing. Such training also considers the authority to process personally identifiable information documented in privacy policies and notices, system of records notices, computer matching agreements and notices, privacy impact assessments, PRIVACT statements, contracts, information sharing agreements, memoranda of understanding, and/or other documentation. |
What is AT-4 Training Records? | Documentation for specialized training may be maintained by individual supervisors at the discretion of the organization. The National Archives and Records Administration provides guidance on records retention for federal agencies. |
What is AT-6 Training Feedback? | Training feedback includes awareness training results and role-based training results. Training results, especially failures of personnel in critical roles, can be indicative of a potentially serious problem. Therefore, it is important that senior managers are made aware of such situations so that they can take appropriate response actions. Training feedback supports the evaluation and update of organizational training described in AT-2b and AT-3b. |
What is AU-1 Policy and Procedures? | Audit and accountability policy and procedures address the controls in the AU family that are implemented within systems and organizations. The risk management strategy is an important factor in establishing such policies and procedures. Policies and procedures contribute to security and privacy assurance. Therefore, it is important that security and privacy programs collaborate on the development of audit and accountability policy and procedures. Security and privacy program policies and procedures at the organization level are preferable, in general, and may obviate the need for mission- or system-specific policies and procedures. The policy can be included as part of the general security and privacy policy or be represented by multiple policies that reflect the complex nature of organizations. Procedures can be established for security and privacy programs, for mission or business processes, and for systems, if needed. Procedures describe how the policies or controls are implemented and can be directed at the individual or role that is the object of the procedure. Procedures can be documented in system security and privacy plans or in one or more separate documents. Events that may precipitate an update to audit and accountability policy and procedures include assessment or audit findings, security incidents or breaches, or changes in applicable laws, executive orders, directives, regulations, policies, standards, and guidelines. Simply restating controls does not constitute an organizational policy or procedure. |
What is AU-2 Event Logging? | 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-3(10), AC-6(9), AC-17(1), CM-3f, CM-5(1), IA-3(3)(b), MA-4(1), MP-4(2), PE-3, PM-21, PT-7, RA-8, SC-7(9), SC-7(15), SI-3(8), SI-4(22), SI-7(8), and 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. |
What is AU-3 Content of Audit Records? | Audit record content that may be necessary to support the auditing function includes event descriptions (item a), time stamps (item b), source and destination addresses (item c), user or process identifiers (items d and f), success or fail indications (item e), and filenames involved (items a, c, e, and f) . Event outcomes include indicators of event success or failure and event-specific results, such as the system security and privacy posture after the event occurred. Organizations consider how audit records can reveal information about individuals that may give rise to privacy risks 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 trail records inputs or is based on patterns or time of usage. |
What is AU-3(1) Content of Audit Records | Additional Audit Information? | The ability to add information generated in audit records is dependent on system functionality to configure the audit record content. Organizations may consider additional information in audit records including, but not limited to, access control or flow control rules invoked and individual identities of group account users. Organizations may also consider limiting additional audit record information to only information that is explicitly needed for audit requirements. This facilitates the use of audit trails and audit logs by not including information in audit records that could potentially be misleading, make it more difficult to locate information of interest, or increase the risk to individuals' privacy. |
What is AU-3(3) Content of Audit Records | Limit Personally Identifiable Information Elements? | Limiting personally identifiable information in audit records when such information is not needed for operational purposes helps reduce the level of privacy risk created by a system. |
What is AU-4 Audit Log Storage Capacity? | Organizations consider the types of audit logging to be performed and the audit log processing requirements when allocating audit log storage capacity. Allocating sufficient audit log storage capacity reduces the likelihood of such capacity being exceeded and resulting in the potential loss or reduction of audit logging capability. |
What is AU-4(1) Audit Log Storage Capacity | Transfer to Alternate Storage? | Audit log transfer, also known as off-loading, is a common process in systems with limited audit log storage capacity and thus supports availability of the audit logs. The initial audit log storage is only used in a transitory fashion until the system can communicate with the secondary or alternate system allocated to audit log storage, at which point the audit logs are transferred. Transferring audit logs to alternate storage is similar to AU-9(2) in that audit logs are transferred to a different entity. However, the purpose of selecting AU-9(2) is to protect the confidentiality and integrity of audit records. Organizations can select either control enhancement to obtain the benefit of increased audit log storage capacity and preserving the confidentiality, integrity, and availability of audit records and logs. |
What is AU-5 Response to Audit Logging Process Failures? | Audit logging process failures include software and hardware errors, failures in audit log capturing mechanisms, and reaching or exceeding audit log storage capacity. Organization-defined actions include overwriting oldest audit records, shutting down the system, and stopping the generation of audit records. Organizations may choose to define additional actions for audit logging process failures based on the type of failure, the location of the failure, the severity of the failure, or a combination of such factors. When the audit logging process failure is related to storage, the response is carried out for the audit log storage repository (i.e., the distinct system component where the audit logs are stored), the system on which the audit logs reside, the total audit log storage capacity of the organization (i.e., all audit log storage repositories combined), or all three. Organizations may decide to take no additional actions after alerting designated roles or personnel. |
What is AU-5(1) Response to Audit Logging Process Failures | Storage Capacity Warning? | Organizations may have multiple audit log storage repositories distributed across multiple system components with each repository having different storage volume capacities. |
What is AU-5(2) Response to Audit Logging Process Failures | Real-time Alerts? | Alerts provide organizations with urgent messages. Real-time alerts provide these messages at information technology speed (i.e., the time from event detection to alert occurs in seconds or less). |
What is AU-5(3) Response to Audit Logging Process Failures | Configurable Traffic Volume Thresholds? | Organizations have the capability to reject or delay the processing of network communications traffic if audit logging information about such traffic is determined to exceed the storage capacity of the system audit logging function. The rejection or delay response is triggered by the established organizational traffic volume thresholds that can be adjusted based on changes to audit log storage capacity. |
What is AU-5(4) Response to Audit Logging Process Failures | Shutdown on Failure? | Organizations determine the types of audit logging failures that can trigger automatic system shutdowns or degraded operations. Because of the importance of ensuring mission and business continuity, organizations may determine that the nature of the audit logging failure is not so severe that it warrants a complete shutdown of the system supporting the core organizational mission and business functions. In those instances, partial system shutdowns or operating in a degraded mode with reduced capability may be viable alternatives. |
What is AU-5(5) Response to Audit Logging Process Failures | Alternate Audit Logging Capability? | Since an alternate audit logging capability may be a short-term protection solution employed until the failure in the primary audit logging capability is corrected, organizations may determine that the alternate audit logging capability need only provide a subset of the primary audit logging functionality that is impacted by the failure. |
What is AU-6 Audit Record Review, Analysis, and Reporting? | Audit record review, analysis, and reporting covers information security- and privacy-related logging performed by organizations, including logging that results from the monitoring of account usage, remote access, wireless connectivity, mobile device connection, configuration settings, system component inventory, use of maintenance tools and non-local maintenance, physical access, temperature and humidity, equipment delivery and removal, communications at system interfaces, and use of mobile code or Voice over Internet Protocol (VoIP). Findings can be reported to organizational entities that include the incident response team, help desk, and security or privacy offices. If organizations are prohibited from reviewing and analyzing audit records or unable to conduct such activities, the review or analysis may be carried out by other organizations granted such authority. The frequency, scope, and/or depth of the audit record review, analysis, and reporting may be adjusted to meet organizational needs based on new information received. |
What is AU-6(1) Audit Record Review, Analysis, and Reporting | Automated Process Integration? | Organizational processes that benefit from integrated audit record review, analysis, and reporting include incident response, continuous monitoring, contingency planning, investigation and response to suspicious activities, and Inspector General audits. |
What is AU-6(3) Audit Record Review, Analysis, and Reporting | Correlate Audit Record Repositories? | Organization-wide situational awareness includes awareness across all three levels of risk management (i.e., organizational level, mission/business process level, and information system level) and supports cross-organization awareness. |
What is AU-6(4) Audit Record Review, Analysis, and Reporting | Central Review and Analysis? | Automated mechanisms for centralized reviews and analyses include Security Information and Event Management products. |
What is AU-6(5) Audit Record Review, Analysis, and Reporting | Integrated Analysis of Audit Records? | Integrated analysis of audit records does not require vulnerability scanning, the generation of performance data, or system monitoring. Rather, integrated analysis requires that the analysis of information generated by scanning, monitoring, or other data collection activities is integrated with the analysis of audit record information. Security Information and Event Management tools can facilitate audit record aggregation or consolidation from multiple system components as well as audit record correlation and analysis. The use of standardized audit record analysis scripts developed by organizations (with localized script adjustments, as necessary) provides more cost-effective approaches for analyzing audit record information collected. The correlation of audit record information with vulnerability scanning information is important in determining the veracity of vulnerability scans of the system and in correlating attack detection events with scanning results. Correlation with performance data can uncover denial-of-service attacks or other types of attacks that result in the unauthorized use of resources. Correlation with system monitoring information can assist in uncovering attacks and in better relating audit information to operational situations. |
What is AU-6(6) Audit Record Review, Analysis, and Reporting | Correlation with Physical Monitoring? | The correlation of physical audit record information and the audit records from systems may assist organizations in identifying suspicious behavior or supporting evidence of such behavior. For example, the correlation of an individual’s identity for logical access to certain systems with the additional physical security information that the individual was present at the facility when the logical access occurred may be useful in investigations. |
What is AU-6(7) Audit Record Review, Analysis, and Reporting | Permitted Actions? | Organizations specify permitted actions for system processes, roles, and users associated with the review, analysis, and reporting of audit records through system account management activities. Specifying permitted actions on audit record information is a way to enforce the principle of least privilege. Permitted actions are enforced by the system and include read, write, execute, append, and delete. |
What is AU-6(8) Audit Record Review, Analysis, and Reporting | Full Text Analysis of Privileged Commands? | Full text analysis of privileged commands requires a distinct environment for the analysis of audit record information related to privileged users without compromising such information on the system where the users have elevated privileges, including the capability to execute privileged commands. Full text analysis refers to analysis that considers the full text of privileged commands (i.e., commands and parameters) as opposed to analysis that considers only the name of the command. Full text analysis includes the use of pattern matching and heuristics. |
What is AU-6(9) Audit Record Review, Analysis, and Reporting | Correlation with Information from Nontechnical Sources? | Nontechnical sources include records that document organizational policy violations related to harassment incidents and the improper use of information assets. Such information can lead to a directed analytical effort to detect potential malicious insider activity. Organizations limit access to information that is available from nontechnical sources due to its sensitive nature. Limited access minimizes the potential for inadvertent release of privacy-related information to individuals who do not have a need to know. The correlation of information from nontechnical sources with audit record information generally occurs only when individuals are suspected of being involved in an incident. Organizations obtain legal advice prior to initiating such actions. |
What is AU-7 Audit Record Reduction and Report Generation? | Audit record reduction is a process that manipulates collected audit log information and organizes it into a summary format that is more meaningful to analysts. Audit record reduction and report generation capabilities do not always emanate from the same system or from the same organizational entities that conduct audit logging activities. The audit record reduction capability includes modern data mining techniques with advanced data filters to identify anomalous behavior in audit records. The report generation capability provided by the system can generate customizable reports. Time ordering of audit records can be an issue if the granularity of the timestamp in the record is insufficient. |
What is AU-7(1) Audit Record Reduction and Report Generation | Automatic Processing? | Events of interest can be identified by the content of audit records, including system resources involved, information objects accessed, identities of individuals, event types, event locations, event dates and times, Internet Protocol addresses involved, or event success or failure. Organizations may define event criteria to any degree of granularity required, such as locations selectable by a general networking location or by specific system component. |
What is AU-8 Time Stamps? | Time stamps generated by the system include date and time. Time is commonly expressed in Coordinated Universal Time (UTC), a modern continuation of Greenwich Mean Time (GMT), or local time with an offset from UTC. Granularity of time measurements refers to the degree of synchronization between system clocks and reference clocks (e.g., clocks synchronizing within hundreds of milliseconds or tens of milliseconds). Organizations may define different time granularities for different system components. Time service can be critical to other security capabilities such as access control and identification and authentication, depending on the nature of the mechanisms used to support those capabilities. |
What is AU-9 Protection of Audit Information? | Audit information includes all information needed to successfully audit system activity, such as audit records, audit log settings, audit reports, and personally identifiable information. Audit logging tools are those programs and devices used to conduct system audit and logging activities. Protection of audit information focuses on technical protection and limits the ability to access and execute audit logging tools to authorized individuals. Physical protection of audit information is addressed by both media protection controls and physical and environmental protection controls. |
What is AU-9(1) Protection of Audit Information | Hardware Write-once Media? | Writing audit trails to hardware-enforced, write-once media applies to the initial generation of audit trails (i.e., the collection of audit records that represents the information to be used for detection, analysis, and reporting purposes) and to the backup of those audit trails. Writing audit trails to hardware-enforced, write-once media does not apply to the initial generation of audit records prior to being written to an audit trail. Write-once, read-many (WORM) media includes Compact Disc-Recordable (CD-R), Blu-Ray Disc Recordable (BD-R), and Digital Versatile Disc-Recordable (DVD-R). In contrast, the use of switchable write-protection media, such as tape cartridges, Universal Serial Bus (USB) drives, Compact Disc Re-Writeable (CD-RW), and Digital Versatile Disc-Read Write (DVD-RW) results in write-protected but not write-once media. |
What is AU-9(2) Protection of Audit Information | Store on Separate Physical Systems or Components? | Storing audit records in a repository separate from the audited system or system component helps to ensure that a compromise of the system being audited does not also result in a compromise of the audit records. Storing audit records on separate physical systems or components also preserves the confidentiality and integrity of audit records and facilitates the management of audit records as an organization-wide activity. Storing audit records on separate systems or components applies to initial generation as well as backup or long-term storage of audit records. |
What is AU-9(3) Protection of Audit Information | Cryptographic Protection? | Cryptographic mechanisms used for protecting the integrity of audit information include signed hash functions using asymmetric cryptography. This enables the distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash. |
What is AU-9(4) Protection of Audit Information | Access by Subset of Privileged Users? | Individuals or roles with privileged access to a system and who are also the subject of an audit by that system may affect the reliability of the audit information by inhibiting audit activities or modifying audit records. Requiring privileged access to be further defined between audit-related privileges and other privileges limits the number of users or roles with audit-related privileges. |
What is AU-9(5) Protection of Audit Information | Dual Authorization? | Organizations may choose different selection options for different types of audit information. Dual authorization mechanisms (also known as two-person control) require the approval of two authorized individuals to execute audit functions. To reduce the risk of collusion, organizations consider rotating dual authorization duties to other individuals. Organizations do not require dual authorization mechanisms when immediate responses are necessary to ensure public and environmental safety. |
What is AU-9(6) Protection of Audit Information | Read-only Access? | Restricting privileged user or role authorizations to read-only helps to limit the potential damage to organizations that could be initiated by such users or roles, such as deleting audit records to cover up malicious activity. |
What is AU-9(7) Protection of Audit Information | Store on Component with Different Operating System? | Storing auditing information on a system component running a different operating system reduces the risk of a vulnerability specific to the system, resulting in a compromise of the audit records. |
What is AU-10 Non-repudiation? | Types of individual actions covered by non-repudiation include creating information, sending and receiving messages, and approving information. Non-repudiation protects against claims by authors of not having authored certain documents, senders of not having transmitted messages, receivers of not having received messages, and signatories of not having signed documents. Non-repudiation services can be used to determine if information originated from an individual or if an individual took specific actions (e.g., sending an email, signing a contract, approving a procurement request, or receiving specific information). Organizations obtain non-repudiation services by employing various techniques or mechanisms, including digital signatures and digital message receipts. |
What is AU-10(1) Non-repudiation | Association of Identities? | Binding identities to the information supports audit requirements that provide organizational personnel with the means to identify who produced specific information in the event of an information transfer. Organizations determine and approve the strength of attribute binding between the information producer and the information based on the security category of the information and other relevant risk factors. |
What is AU-10(2) Non-repudiation | Validate Binding of Information Producer Identity? | Validating the binding of the information producer identity to the information prevents the modification of information between production and review. The validation of bindings can be achieved by, for example, using cryptographic checksums. Organizations determine if validations are in response to user requests or generated automatically. |
What is AU-10(3) Non-repudiation | Chain of Custody? | Chain of custody is a process that tracks the movement of evidence through its collection, safeguarding, and analysis life cycle by documenting each individual who handled the evidence, the date and time the evidence was collected or transferred, and the purpose for the transfer. If the reviewer is a human or if the review function is automated but separate from the release or transfer function, the system associates the identity of the reviewer of the information to be released with the information and the information label. In the case of human reviews, maintaining the credentials of reviewers or releasers provides the organization with the means to identify who reviewed and released the information. In the case of automated reviews, it ensures that only approved review functions are used. |
What is AU-10(4) Non-repudiation | Validate Binding of Information Reviewer Identity? | Validating the binding of the information reviewer identity to the information at transfer or release points prevents the unauthorized modification of information between review and the transfer or release. The validation of bindings can be achieved by using cryptographic checksums. Organizations determine if validations are in response to user requests or generated automatically. |
What is AU-11 Audit Record Retention? | Organizations retain audit records until it is determined that the records are no longer needed for administrative, legal, audit, or other operational purposes. This includes the retention and availability of audit records relative to Freedom of Information Act (FOIA) requests, subpoenas, and law enforcement actions. Organizations develop standard categories of audit records relative to such types of actions and standard response processes for each type of action. The National Archives and Records Administration (NARA) General Records Schedules provide federal policy on records retention. |
What is AU-11(1) Audit Record Retention | Long-term Retrieval Capability? | Organizations need to access and read audit records requiring long-term storage (on the order of years). Measures employed to help facilitate the retrieval of audit records include converting records to newer formats, retaining equipment capable of reading the records, and retaining the necessary documentation to help personnel understand how to interpret the records. |
What is AU-12 Audit Record Generation? | Audit records can be generated from many different system components. The event types specified in AU-2d are the event types for which audit logs are to be generated and are a subset of all event types for which the system can generate audit records. |
What is AU-12(1) Audit Record Generation | System-wide and Time-correlated Audit Trail? | Audit trails are time-correlated if the time stamps in the individual audit records can be reliably related to the time stamps in other audit records to achieve a time ordering of the records within organizational tolerances. |
What is AU-12(2) Audit Record Generation | Standardized Formats? | Audit records that follow common standards promote interoperability and information exchange between devices and systems. Promoting interoperability and information exchange facilitates the production of event information that can be readily analyzed and correlated. If logging mechanisms do not conform to standardized formats, systems may convert individual audit records into standardized formats when compiling system-wide audit trails. |
What is AU-12(3) Audit Record Generation | Changes by Authorized Individuals? | Permitting authorized individuals to make changes to system logging enables organizations to extend or limit logging as necessary to meet organizational requirements. Logging that is limited to conserve system resources may be extended (either temporarily or permanently) to address certain threat situations. In addition, logging may be limited to a specific set of event types to facilitate audit reduction, analysis, and reporting. Organizations can establish time thresholds in which logging actions are changed (e.g., near real-time, within minutes, or within hours). |
What is AU-12(4) Audit Record Generation | Query Parameter Audits of Personally Identifiable Information? | Query parameters are explicit criteria that an individual or automated system submits to a system to retrieve data. Auditing of query parameters for datasets that contain personally identifiable information augments the capability of an organization to track and understand the access, usage, or sharing of personally identifiable information by authorized personnel. |
What is AU-13 Monitoring for Information Disclosure? | Unauthorized disclosure of information is a form of data leakage. Open-source information includes social networking sites and code-sharing platforms and repositories. Examples of organizational information include personally identifiable information retained by the organization or proprietary information generated by the organization. |
What is AU-13(1) Monitoring for Information Disclosure | Use of Automated Tools? | Automated mechanisms include commercial services that provide notifications and alerts to organizations and automated scripts to monitor new posts on websites. |
What is AU-13(2) Monitoring for Information Disclosure | Review of Monitored Sites? | Reviewing the current list of open-source information sites being monitored on a regular basis helps to ensure that the selected sites remain relevant. The review also provides the opportunity to add new open-source information sites with the potential to provide evidence of unauthorized disclosure of organizational information. The list of sites monitored can be guided and informed by threat intelligence of other credible sources of information. |
What is AU-13(3) Monitoring for Information Disclosure | Unauthorized Replication of Information? | The unauthorized use or replication of organizational information by external entities can cause adverse impacts on organizational operations and assets, including damage to reputation. Such activity can include the replication of an organizational website by an adversary or hostile threat actor who attempts to impersonate the web-hosting organization. Discovery tools, techniques, and processes used to determine if external entities are replicating organizational information in an unauthorized manner include scanning external websites, monitoring social media, and training staff to recognize the unauthorized use of organizational information. |
What is AU-14 Session Audit? | Session audits can include monitoring keystrokes, tracking websites visited, and recording information and/or file transfers. Session audit capability is implemented in addition to event logging and may involve implementation of specialized session capture technology. Organizations consider how session auditing can reveal information about individuals that may give rise to privacy risk as well as how to mitigate those risks. Because session auditing can impact system and network performance, organizations activate the capability under well-defined situations (e.g., the organization is suspicious of a specific individual). Organizations consult with legal counsel, civil liberties officials, and privacy officials to ensure that any legal, privacy, civil rights, or civil liberties issues, including the use of personally identifiable information, are appropriately addressed. |
What is AU-14(1) Session Audit | System Start-up? | The automatic initiation of session audits at startup helps to ensure that the information being captured on selected individuals is complete and not subject to compromise through tampering by malicious threat actors. |
What is AU-14(3) Session Audit | Remote Viewing and Listening? | None. |
What is AU-16 Cross-organizational Audit Logging? | When organizations use systems or services of external organizations, the audit logging capability necessitates a coordinated, cross-organization approach. For example, maintaining the identity of individuals who request specific services across organizational boundaries may often be difficult, and doing so may prove to have significant performance and privacy ramifications. Therefore, it is often the case that cross-organizational audit logging simply captures the identity of individuals who issue requests at the initial system, and subsequent systems record that the requests originated from authorized individuals. Organizations consider including processes for coordinating audit information requirements and protection of audit information in information exchange agreements. |
What is AU-16(1) Cross-organizational Audit Logging | Identity Preservation? | Identity preservation is applied when there is a need to be able to trace actions that are performed across organizational boundaries to a specific individual. |