question
stringlengths 21
136
| answer
stringlengths 5
3.93k
|
|---|---|
What is PT-4(2) Consent | Just-in-time Consent? | Just-in-time consent enables individuals to participate in how their personally identifiable information is being processed at the time or in conjunction with specific types of data processing when such participation may be most useful to the individual. Individual assumptions about how personally identifiable information is being processed might not be accurate or reliable if time has passed since the individual last gave consent or the type of processing creates significant privacy risk. Organizations use discretion to determine when to use just-in-time consent and may use supporting information on demographics, focus groups, or surveys to learn more about individuals’ privacy interests and concerns. |
What is PT-4(3) Consent | Revocation? | Revocation of consent enables individuals to exercise control over their initial consent decision when circumstances change. Organizations consider usability factors in enabling easy-to-use revocation capabilities. |
What is PT-5 Privacy Notice? | Privacy notices help inform individuals about how their personally identifiable information is being processed by the system or organization. Organizations use privacy notices to inform individuals about how, under what authority, and for what purpose their personally identifiable information is processed, as well as other information such as choices individuals might have with respect to that processing and other parties with whom information is shared. Laws, executive orders, directives, regulations, or policies may require that privacy notices include specific elements or be provided in specific formats. Federal agency personnel consult with the senior agency official for privacy and legal counsel regarding when and where to provide privacy notices, as well as elements to include in privacy notices and required formats. In circumstances where laws or government-wide policies do not require privacy notices, organizational policies and determinations may require privacy notices and may serve as a source of the elements to include in privacy notices.
Privacy risk assessments identify the privacy risks associated with the processing of personally identifiable information and may help organizations determine appropriate elements to include in a privacy notice to manage such risks. To help individuals understand how their information is being processed, organizations write materials in plain language and avoid technical jargon. |
What is PT-5(1) Privacy Notice | Just-in-time Notice? | Just-in-time notices inform individuals of how organizations process their personally identifiable information at a time when such notices may be most useful to the individuals. Individual assumptions about how personally identifiable information will be processed might not be accurate or reliable if time has passed since the organization last presented notice or the circumstances under which the individual was last provided notice have changed. A just-in-time notice can explain data actions that organizations have identified as potentially giving rise to greater privacy risk for individuals. Organizations can use a just-in-time notice to update or remind individuals about specific data actions as they occur or highlight specific changes that occurred since last presenting notice. A just-in-time notice can be used in conjunction with just-in-time consent to explain what will occur if consent is declined. Organizations use discretion to determine when to use a just-in-time notice and may use supporting information on user demographics, focus groups, or surveys to learn about users’ privacy interests and concerns. |
What is PT-5(2) Privacy Notice | Privacy Act Statements? | If a federal agency asks individuals to supply information that will become part of a system of records, the agency is required to provide a PRIVACT statement on the form used to collect the information or on a separate form that can be retained by the individual. The agency provides a PRIVACT statement in such circumstances regardless of whether the information will be collected on a paper or electronic form, on a website, on a mobile application, over the telephone, or through some other medium. This requirement ensures that the individual is provided with sufficient information about the request for information to make an informed decision on whether or not to respond.
PRIVACT statements provide formal notice to individuals of the authority that authorizes the solicitation of the information; whether providing the information is mandatory or voluntary; the principal purpose(s) for which the information is to be used; the published routine uses to which the information is subject; the effects on the individual, if any, of not providing all or any part of the information requested; and an appropriate citation and link to the relevant system of records notice. Federal agency personnel consult with the senior agency official for privacy and legal counsel regarding the notice provisions of the PRIVACT. |
What is PT-6 System of Records Notice? | The PRIVACT requires that federal agencies publish a system of records notice in the Federal Register upon the establishment and/or modification of a PRIVACT system of records. As a general matter, a system of records notice is required when an agency maintains a group of any records under the control of the agency from which information is retrieved by the name of an individual or by some identifying number, symbol, or other identifier. The notice describes the existence and character of the system and identifies the system of records, the purpose(s) of the system, the authority for maintenance of the records, the categories of records maintained in the system, the categories of individuals about whom records are maintained, the routine uses to which the records are subject, and additional details about the system as described in OMB A-108. |
What is PT-6(1) System of Records Notice | Routine Uses? | A PRIVACT routine use is a particular kind of disclosure of a record outside of the federal agency maintaining the system of records. A routine use is an exception to the PRIVACT prohibition on the disclosure of a record in a system of records without the prior written consent of the individual to whom the record pertains. To qualify as a routine use, the disclosure must be for a purpose that is compatible with the purpose for which the information was originally collected. The PRIVACT requires agencies to describe each routine use of the records maintained in the system of records, including the categories of users of the records and the purpose of the use. Agencies may only establish routine uses by explicitly publishing them in the relevant system of records notice. |
What is PT-6(2) System of Records Notice | Exemption Rules? | The PRIVACT includes two sets of provisions that allow federal agencies to claim exemptions from certain requirements in the statute. In certain circumstances, these provisions allow agencies to promulgate regulations to exempt a system of records from select provisions of the PRIVACT. At a minimum, organizations’ PRIVACT exemption regulations include the specific name(s) of any system(s) of records that will be exempt, the specific provisions of the PRIVACT from which the system(s) of records is to be exempted, the reasons for the exemption, and an explanation for why the exemption is both necessary and appropriate. |
What is PT-7 Specific Categories of Personally Identifiable Information? | Organizations apply any conditions or protections that may be necessary for specific categories of personally identifiable information. These conditions may be required by laws, executive orders, directives, regulations, policies, standards, or guidelines. The requirements may also come from the results of privacy risk assessments that factor in contextual changes that may result in an organizational determination that a particular category of personally identifiable information is particularly sensitive or raises particular privacy risks. Organizations consult with the senior agency official for privacy and legal counsel regarding any protections that may be necessary. |
What is PT-7(1) Specific Categories of Personally Identifiable Information | Social Security Numbers? | Federal law and policy establish specific requirements for organizations’ processing of Social Security numbers. Organizations take steps to eliminate unnecessary uses of Social Security numbers and other sensitive information and observe any particular requirements that apply. |
What is PT-7(2) Specific Categories of Personally Identifiable Information | First Amendment Information? | The PRIVACT limits agencies’ ability to process information that describes how individuals exercise rights guaranteed by the First Amendment. Organizations consult with the senior agency official for privacy and legal counsel regarding these requirements. |
What is PT-8 Computer Matching Requirements? | The PRIVACT establishes requirements for federal and non-federal agencies if they engage in a matching program. In general, a matching program is a computerized comparison of records from two or more automated PRIVACT systems of records or an automated system of records and automated records maintained by a non-federal agency (or agent thereof). A matching program either pertains to federal benefit programs or federal personnel or payroll records. A federal benefit match is performed to determine or verify eligibility for payments under federal benefit programs or to recoup payments or delinquent debts under federal benefit programs. A matching program involves not just the matching activity itself but also the investigative follow-up and ultimate action, if any. |
What is RA-1 Policy and Procedures? | Risk assessment policy and procedures address the controls in the RA 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 risk assessment 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 reflecting 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 risk assessment policy and procedures include assessment or audit findings, security incidents or breaches, or changes in laws, executive orders, directives, regulations, policies, standards, and guidelines. Simply restating controls does not constitute an organizational policy or procedure. |
What is RA-2 Security Categorization? | Security categories describe the potential adverse impacts or negative consequences to organizational operations, organizational assets, and individuals if organizational information and systems are compromised through a loss of confidentiality, integrity, or availability. Security categorization is also a type of asset loss characterization in systems security engineering processes that is carried out throughout the system development life cycle. Organizations can use privacy risk assessments or privacy impact assessments to better understand the potential adverse effects on individuals. CNSSI 1253 provides additional guidance on categorization for national security systems.
Organizations conduct the security categorization process as an organization-wide activity with the direct involvement of chief information officers, senior agency information security officers, senior agency officials for privacy, system owners, mission and business owners, and information owners or stewards. Organizations consider the potential adverse impacts to other organizations and, in accordance with USA PATRIOT and Homeland Security Presidential Directives, potential national-level adverse impacts.
Security categorization processes facilitate the development of inventories of information assets and, along with CM-8, mappings to specific system components where information is processed, stored, or transmitted. The security categorization process is revisited throughout the system development life cycle to ensure that the security categories remain accurate and relevant. |
What is RA-2(1) Security Categorization | Impact-level Prioritization? | Organizations apply the high-water mark concept to each system categorized in accordance with FIPS 199, resulting in systems designated as low impact, moderate impact, or high impact. Organizations that desire additional granularity in the system impact designations for risk-based decision-making, can further partition the systems into sub-categories of the initial system categorization. For example, an impact-level prioritization on a moderate-impact system can produce three new sub-categories: low-moderate systems, moderate-moderate systems, and high-moderate systems. Impact-level prioritization and the resulting sub-categories of the system give organizations an opportunity to focus their investments related to security control selection and the tailoring of control baselines in responding to identified risks. Impact-level prioritization can also be used to determine those systems that may be of heightened interest or value to adversaries or represent a critical loss to the federal enterprise, sometimes described as high value assets. For such high value assets, organizations may be more focused on complexity, aggregation, and information exchanges. Systems with high value assets can be prioritized by partitioning high-impact systems into low-high systems, moderate-high systems, and high-high systems. Alternatively, organizations can apply the guidance in CNSSI 1253 for security objective-related categorization. |
What is RA-3 Risk Assessment? | Risk assessments consider threats, vulnerabilities, likelihood, and impact to organizational operations and assets, individuals, other organizations, and the Nation. Risk assessments also consider risk from external parties, including contractors who operate systems on behalf of the organization, individuals who access organizational systems, service providers, and outsourcing entities.
Organizations can conduct risk assessments at all three levels in the risk management hierarchy (i.e., organization level, mission/business process level, or information system level) and at any stage in the system development life cycle. Risk assessments can also be conducted at various steps in the Risk Management Framework, including preparation, categorization, control selection, control implementation, control assessment, authorization, and control monitoring. Risk assessment is an ongoing activity carried out throughout the system development life cycle.
Risk assessments can also address information related to the system, including system design, the intended use of the system, testing results, and supply chain-related information or artifacts. Risk assessments can play an important role in control selection processes, particularly during the application of tailoring guidance and in the earliest phases of capability determination. |
What is RA-3(1) Risk Assessment | Supply Chain Risk Assessment? | Supply chain-related events include disruption, use of defective components, insertion of counterfeits, theft, malicious development practices, improper delivery practices, and insertion of malicious code. These events can have a significant impact on the confidentiality, integrity, or availability of a system and its information and, therefore, can also adversely impact organizational operations (including mission, functions, image, or reputation), organizational assets, individuals, other organizations, and the Nation. The supply chain-related events may be unintentional or malicious and can occur at any point during the system life cycle. An analysis of supply chain risk can help an organization identify systems or components for which additional supply chain risk mitigations are required. |
What is RA-3(2) Risk Assessment | Use of All-source Intelligence? | Organizations employ all-source intelligence to inform engineering, acquisition, and risk management decisions. All-source intelligence consists of information derived from all available sources, including publicly available or open-source information, measurement and signature intelligence, human intelligence, signals intelligence, and imagery intelligence. All-source intelligence is used to analyze the risk of vulnerabilities (both intentional and unintentional) from development, manufacturing, and delivery processes, people, and the environment. The risk analysis may be performed on suppliers at multiple tiers in the supply chain sufficient to manage risks. Organizations may develop agreements to share all-source intelligence information or resulting decisions with other organizations, as appropriate. |
What is RA-3(3) Risk Assessment | Dynamic Threat Awareness? | The threat awareness information that is gathered feeds into the organization’s information security operations to ensure that procedures are updated in response to the changing threat environment. For example, at higher threat levels, organizations may change the privilege or authentication thresholds required to perform certain operations. |
What is RA-3(4) Risk Assessment | Predictive Cyber Analytics? | A properly resourced Security Operations Center (SOC) or Computer Incident Response Team (CIRT) may be overwhelmed by the volume of information generated by the proliferation of security tools and appliances unless it employs advanced automation and analytics to analyze the data. Advanced automation and analytics capabilities are typically supported by artificial intelligence concepts, including machine learning. Examples include Automated Threat Discovery and Response (which includes broad-based collection, context-based analysis, and adaptive response capabilities), automated workflow operations, and machine assisted decision tools. Note, however, that sophisticated adversaries may be able to extract information related to analytic parameters and retrain the machine learning to classify malicious activity as benign. Accordingly, machine learning is augmented by human monitoring to ensure that sophisticated adversaries are not able to conceal their activities. |
What is RA-5 Vulnerability Monitoring and Scanning? | Security categorization of information and systems guides the frequency and comprehensiveness of vulnerability monitoring (including scans). Organizations determine the required vulnerability monitoring for system components, ensuring that the potential sources of vulnerabilities—such as infrastructure components (e.g., switches, routers, guards, sensors), networked printers, scanners, and copiers—are not overlooked. The capability to readily update vulnerability monitoring tools as new vulnerabilities are discovered and announced and as new scanning methods are developed helps to ensure that new vulnerabilities are not missed by employed vulnerability monitoring tools. The vulnerability monitoring tool update process helps to ensure that potential vulnerabilities in the system are identified and addressed as quickly as possible. Vulnerability monitoring and analyses for custom software may require additional approaches, such as static analysis, dynamic analysis, binary analysis, or a hybrid of the three approaches. Organizations can use these analysis approaches in source code reviews and in a variety of tools, including web-based application scanners, static analysis tools, and binary analyzers.
Vulnerability monitoring includes scanning for patch levels; scanning for functions, ports, protocols, and services that should not be accessible to users or devices; and scanning for flow control mechanisms that are improperly configured or operating incorrectly. Vulnerability monitoring may also include continuous vulnerability monitoring tools that use instrumentation to continuously analyze components. Instrumentation-based tools may improve accuracy and may be run throughout an organization without scanning. Vulnerability monitoring tools that facilitate interoperability include tools that are Security Content Automated Protocol (SCAP)-validated. Thus, organizations consider using scanning tools that express vulnerabilities in the Common Vulnerabilities and Exposures (CVE) naming convention and that employ the Open Vulnerability Assessment Language (OVAL) to determine the presence of vulnerabilities. Sources for vulnerability information include the Common Weakness Enumeration (CWE) listing and the National Vulnerability Database (NVD). Control assessments, such as red team exercises, provide additional sources of potential vulnerabilities for which to scan. Organizations also consider using scanning tools that express vulnerability impact by the Common Vulnerability Scoring System (CVSS).
Vulnerability monitoring includes a channel and process for receiving reports of security vulnerabilities from the public at-large. Vulnerability disclosure programs can be as simple as publishing a monitored email address or web form that can receive reports, including notification authorizing good-faith research and disclosure of security vulnerabilities. Organizations generally expect that such research is happening with or without their authorization and can use public vulnerability disclosure channels to increase the likelihood that discovered vulnerabilities are reported directly to the organization for remediation.
Organizations may also employ the use of financial incentives (also known as bug bounties) to further encourage external security researchers to report discovered vulnerabilities. Bug bounty programs can be tailored to the organization’s needs. Bounties can be operated indefinitely or over a defined period of time and can be offered to the general public or to a curated group. Organizations may run public and private bounties simultaneously and could choose to offer partially credentialed access to certain participants in order to evaluate security vulnerabilities from privileged vantage points. |
What is RA-5(2) Vulnerability Monitoring and Scanning | Update Vulnerabilities to Be Scanned? | Due to the complexity of modern software, systems, and other factors, new vulnerabilities are discovered on a regular basis. It is important that newly discovered vulnerabilities are added to the list of vulnerabilities to be scanned to ensure that the organization can take steps to mitigate those vulnerabilities in a timely manner. |
What is RA-5(3) Vulnerability Monitoring and Scanning | Breadth and Depth of Coverage? | The breadth of vulnerability scanning coverage can be expressed as a percentage of components within the system, by the particular types of systems, by the criticality of systems, or by the number of vulnerabilities to be checked. Conversely, the depth of vulnerability scanning coverage can be expressed as the level of the system design that the organization intends to monitor (e.g., component, module, subsystem, element). Organizations can determine the sufficiency of vulnerability scanning coverage with regard to its risk tolerance and other factors. Scanning tools and how the tools are configured may affect the depth and coverage. Multiple scanning tools may be needed to achieve the desired depth and coverage. SP 800-53A provides additional information on the breadth and depth of coverage. |
What is RA-5(4) Vulnerability Monitoring and Scanning | Discoverable Information? | Discoverable information includes information that adversaries could obtain without compromising or breaching the system, such as by collecting information that the system is exposing or by conducting extensive web searches. Corrective actions include notifying appropriate organizational personnel, removing designated information, or changing the system to make the designated information less relevant or attractive to adversaries. This enhancement excludes intentionally discoverable information that may be part of a decoy capability (e.g., honeypots, honeynets, or deception nets) deployed by the organization. |
What is RA-5(5) Vulnerability Monitoring and Scanning | Privileged Access? | In certain situations, the nature of the vulnerability scanning may be more intrusive, or the system component that is the subject of the scanning may contain classified or controlled unclassified information, such as personally identifiable information. Privileged access authorization to selected system components facilitates more thorough vulnerability scanning and protects the sensitive nature of such scanning. |
What is RA-5(6) Vulnerability Monitoring and Scanning | Automated Trend Analyses? | Using automated mechanisms to analyze multiple vulnerability scans over time can help determine trends in system vulnerabilities and identify patterns of attack. |
What is RA-5(8) Vulnerability Monitoring and Scanning | Review Historic Audit Logs? | Reviewing historic audit logs to determine if a recently detected vulnerability in a system has been previously exploited by an adversary can provide important information for forensic analyses. Such analyses can help identify, for example, the extent of a previous intrusion, the trade craft employed during the attack, organizational information exfiltrated or modified, mission or business capabilities affected, and the duration of the attack. |
What is RA-5(10) Vulnerability Monitoring and Scanning | Correlate Scanning Information? | An attack vector is a path or means by which an adversary can gain access to a system in order to deliver malicious code or exfiltrate information. Organizations can use attack trees to show how hostile activities by adversaries interact and combine to produce adverse impacts or negative consequences to systems and organizations. Such information, together with correlated data from vulnerability scanning tools, can provide greater clarity regarding multi-vulnerability and multi-hop attack vectors. The correlation of vulnerability scanning information is especially important when organizations are transitioning from older technologies to newer technologies (e.g., transitioning from IPv4 to IPv6 network protocols). During such transitions, some system components may inadvertently be unmanaged and create opportunities for adversary exploitation. |
What is RA-5(11) Vulnerability Monitoring and Scanning | Public Disclosure Program? | The reporting channel is publicly discoverable and contains clear language authorizing good-faith research and the disclosure of vulnerabilities to the organization. The organization does not condition its authorization on an expectation of indefinite non-disclosure to the public by the reporting entity but may request a specific time period to properly remediate the vulnerability. |
What is RA-6 Technical Surveillance Countermeasures Survey? | A technical surveillance countermeasures survey is a service provided by qualified personnel to detect the presence of technical surveillance devices and hazards and to identify technical security weaknesses that could be used in the conduct of a technical penetration of the surveyed facility. Technical surveillance countermeasures surveys also provide evaluations of the technical security posture of organizations and facilities and include visual, electronic, and physical examinations of surveyed facilities, internally and externally. The surveys also provide useful input for risk assessments and information regarding organizational exposure to potential adversaries. |
What is RA-7 Risk Response? | Organizations have many options for responding to risk including mitigating risk by implementing new controls or strengthening existing controls, accepting risk with appropriate justification or rationale, sharing or transferring risk, or avoiding risk. The risk tolerance of the organization influences risk response decisions and actions. Risk response addresses the need to determine an appropriate response to risk before generating a plan of action and milestones entry. For example, the response may be to accept risk or reject risk, or it may be possible to mitigate the risk immediately so that a plan of action and milestones entry is not needed. However, if the risk response is to mitigate the risk, and the mitigation cannot be completed immediately, a plan of action and milestones entry is generated. |
What is RA-8 Privacy Impact Assessments? | A privacy impact assessment is an analysis of how personally identifiable information is handled to ensure that handling conforms to applicable privacy requirements, determine the privacy risks associated with an information system or activity, and evaluate ways to mitigate privacy risks. A privacy impact assessment is both an analysis and a formal document that details the process and the outcome of the analysis.
Organizations conduct and develop a privacy impact assessment with sufficient clarity and specificity to demonstrate that the organization fully considered privacy and incorporated appropriate privacy protections from the earliest stages of the organization’s activity and throughout the information life cycle. In order to conduct a meaningful privacy impact assessment, the organization’s senior agency official for privacy works closely with program managers, system owners, information technology experts, security officials, counsel, and other relevant organization personnel. Moreover, a privacy impact assessment is not a time-restricted activity that is limited to a particular milestone or stage of the information system or personally identifiable information life cycles. Rather, the privacy analysis continues throughout the system and personally identifiable information life cycles. Accordingly, a privacy impact assessment is a living document that organizations update whenever changes to the information technology, changes to the organization’s practices, or other factors alter the privacy risks associated with the use of such information technology.
To conduct the privacy impact assessment, organizations can use security and privacy risk assessments. Organizations may also use other related processes that may have different names, including privacy threshold analyses. A privacy impact assessment can also serve as notice to the public regarding the organization’s practices with respect to privacy. Although conducting and publishing privacy impact assessments may be required by law, organizations may develop such policies in the absence of applicable laws. For federal agencies, privacy impact assessments may be required by EGOV; agencies should consult with their senior agency official for privacy and legal counsel on this requirement and be aware of the statutory exceptions and OMB guidance relating to the provision. |
What is RA-9 Criticality Analysis? | Not all system components, functions, or services necessarily require significant protections. For example, criticality analysis is a key tenet of supply chain risk management and informs the prioritization of protection activities. The identification of critical system components and functions considers applicable laws, executive orders, regulations, directives, policies, standards, system functionality requirements, system and component interfaces, and system and component dependencies. Systems engineers conduct a functional decomposition of a system to identify mission-critical functions and components. The functional decomposition includes the identification of organizational missions supported by the system, decomposition into the specific functions to perform those missions, and traceability to the hardware, software, and firmware components that implement those functions, including when the functions are shared by many components within and external to the system.
The operational environment of a system or a system component may impact the criticality, including the connections to and dependencies on cyber-physical systems, devices, system-of-systems, and outsourced IT services. System components that allow unmediated access to critical system components or functions are considered critical due to the inherent vulnerabilities that such components create. Component and function criticality are assessed in terms of the impact of a component or function failure on the organizational missions that are supported by the system that contains the components and functions.
Criticality analysis is performed when an architecture or design is being developed, modified, or upgraded. If such analysis is performed early in the system development life cycle, organizations may be able to modify the system design to reduce the critical nature of these components and functions, such as by adding redundancy or alternate paths into the system design. Criticality analysis can also influence the protection measures required by development contractors. In addition to criticality analysis for systems, system components, and system services, criticality analysis of information is an important consideration. Such analysis is conducted as part of security categorization in RA-2. |
What is RA-10 Threat Hunting? | Threat hunting is an active means of cyber defense in contrast to traditional protection measures, such as firewalls, intrusion detection and prevention systems, quarantining malicious code in sandboxes, and Security Information and Event Management technologies and systems. Cyber threat hunting involves proactively searching organizational systems, networks, and infrastructure for advanced threats. The objective is to track and disrupt cyber adversaries as early as possible in the attack sequence and to measurably improve the speed and accuracy of organizational responses. Indications of compromise include unusual network traffic, unusual file changes, and the presence of malicious code. Threat hunting teams leverage existing threat intelligence and may create new threat intelligence, which is shared with peer organizations, Information Sharing and Analysis Organizations (ISAO), Information Sharing and Analysis Centers (ISAC), and relevant government departments and agencies. |
What is SA-1 Policy and Procedures? | System and services acquisition policy and procedures address the controls in the SA 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 system and services acquisition 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 system and services acquisition policy and procedures include assessment or audit findings, security incidents or breaches, or changes in laws, executive orders, directives, regulations, policies, standards, and guidelines. Simply restating controls does not constitute an organizational policy or procedure. |
What is SA-2 Allocation of Resources? | Resource allocation for information security and privacy includes funding for system and services acquisition, sustainment, and supply chain-related risks throughout the system development life cycle. |
What is SA-3 System Development Life Cycle? | A system development life cycle process provides the foundation for the successful development, implementation, and operation of organizational systems. The integration of security and privacy considerations early in the system development life cycle is a foundational principle of systems security engineering and privacy engineering. To apply the required controls within the system development life cycle requires a basic understanding of information security and privacy, threats, vulnerabilities, adverse impacts, and risk to critical mission and business functions. The security engineering principles in SA-8 help individuals properly design, code, and test systems and system components. Organizations include qualified personnel (e.g., senior agency information security officers, senior agency officials for privacy, security and privacy architects, and security and privacy engineers) in system development life cycle processes to ensure that established security and privacy requirements are incorporated into organizational systems. Role-based security and privacy training programs can ensure that individuals with key security and privacy roles and responsibilities have the experience, skills, and expertise to conduct assigned system development life cycle activities.
The effective integration of security and privacy requirements into enterprise architecture also helps to ensure that important security and privacy considerations are addressed throughout the system life cycle and that those considerations are directly related to organizational mission and business processes. This process also facilitates the integration of the information security and privacy architectures into the enterprise architecture, consistent with the risk management strategy of the organization. Because the system development life cycle involves multiple organizations, (e.g., external suppliers, developers, integrators, service providers), acquisition and supply chain risk management functions and controls play significant roles in the effective management of the system during the life cycle. |
What is SA-3(1) System Development Life Cycle | Manage Preproduction Environment? | The preproduction environment includes development, test, and integration environments. The program protection planning processes established by the Department of Defense are examples of managing the preproduction environment for defense contractors. Criticality analysis and the application of controls on developers also contribute to a more secure system development environment. |
What is SA-3(2) System Development Life Cycle | Use of Live or Operational Data? | Live data is also referred to as operational data. The use of live or operational data in preproduction (i.e., development, test, and integration) environments can result in significant risks to organizations. In addition, the use of personally identifiable information in testing, research, and training increases the risk of unauthorized disclosure or misuse of such information. Therefore, it is important for the organization to manage any additional risks that may result from the use of live or operational data. Organizations can minimize such risks by using test or dummy data during the design, development, and testing of systems, system components, and system services. Risk assessment techniques may be used to determine if the risk of using live or operational data is acceptable. |
What is SA-3(3) System Development Life Cycle | Technology Refresh? | Technology refresh planning may encompass hardware, software, firmware, processes, personnel skill sets, suppliers, service providers, and facilities. The use of obsolete or nearing obsolete technology may increase the security and privacy risks associated with unsupported components, counterfeit or repurposed components, components unable to implement security or privacy requirements, slow or inoperable components, components from untrusted sources, inadvertent personnel error, or increased complexity. Technology refreshes typically occur during the operations and maintenance stage of the system development life cycle. |
What is SA-4 Acquisition Process? | Security and privacy functional requirements are typically derived from the high-level security and privacy requirements described in SA-2. The derived requirements include security and privacy capabilities, functions, and mechanisms. Strength requirements associated with such capabilities, functions, and mechanisms include degree of correctness, completeness, resistance to tampering or bypass, and resistance to direct attack. Assurance requirements include development processes, procedures, and methodologies as well as the evidence from development and assessment activities that provide grounds for confidence that the required functionality is implemented and possesses the required strength of mechanism. SP 800-160-1 describes the process of requirements engineering as part of the system development life cycle.
Controls can be viewed as descriptions of the safeguards and protection capabilities appropriate for achieving the particular security and privacy objectives of the organization and for reflecting the security and privacy requirements of stakeholders. Controls are selected and implemented in order to satisfy system requirements and include developer and organizational responsibilities. Controls can include technical, administrative, and physical aspects. In some cases, the selection and implementation of a control may necessitate additional specification by the organization in the form of derived requirements or instantiated control parameter values. The derived requirements and control parameter values may be necessary to provide the appropriate level of implementation detail for controls within the system development life cycle.
Security and privacy documentation requirements address all stages of the system development life cycle. Documentation provides user and administrator guidance for the implementation and operation of controls. The level of detail required in such documentation is based on the security categorization or classification level of the system and the degree to which organizations depend on the capabilities, functions, or mechanisms to meet risk response expectations. Requirements can include mandated configuration settings that specify allowed functions, ports, protocols, and services. Acceptance criteria for systems, system components, and system services are defined in the same manner as the criteria for any organizational acquisition or procurement. |
What is SA-4(1) Acquisition Process | Functional Properties of Controls? | Functional properties of security and privacy controls describe the functionality (i.e., security or privacy capability, functions, or mechanisms) visible at the interfaces of the controls and specifically exclude functionality and data structures internal to the operation of the controls. |
What is SA-4(2) Acquisition Process | Design and Implementation Information for Controls? | Organizations may require different levels of detail in the documentation for the design and implementation of controls in organizational systems, system components, or system services based on mission and business requirements, requirements for resiliency and trustworthiness, and requirements for analysis and testing. Systems can be partitioned into multiple subsystems. Each subsystem within the system can contain one or more modules. The high-level design for the system is expressed in terms of subsystems and the interfaces between subsystems providing security-relevant functionality. The low-level design for the system is expressed in terms of modules and the interfaces between modules providing security-relevant functionality. Design and implementation documentation can include manufacturer, version, serial number, verification hash signature, software libraries used, date of purchase or download, and the vendor or download source. Source code and hardware schematics are referred to as the implementation representation of the system. |
What is SA-4(3) Acquisition Process | Development Methods, Techniques, and Practices? | Following a system development life cycle that includes state-of-the-practice software development methods, systems engineering methods, systems security and privacy engineering methods, and quality control processes helps to reduce the number and severity of latent errors within systems, system components, and system services. Reducing the number and severity of such errors reduces the number of vulnerabilities in those systems, components, and services. Transparency in the methods and techniques that developers select and implement for systems engineering, systems security and privacy engineering, software development, component and system assessments, and quality control processes provides an increased level of assurance in the trustworthiness of the system, system component, or system service being acquired. |
What is SA-4(5) Acquisition Process | System, Component, and Service Configurations? | Examples of security configurations include the U.S. Government Configuration Baseline (USGCB), Security Technical Implementation Guides (STIGs), and any limitations on functions, ports, protocols, and services. Security characteristics can include requiring that default passwords have been changed. |
What is SA-4(6) Acquisition Process | Use of Information Assurance Products? | Commercial off-the-shelf IA or IA-enabled information technology products used to protect classified information by cryptographic means may be required to use NSA-approved key management. See NSA CSFC. |
What is SA-4(7) Acquisition Process | NIAP-approved Protection Profiles? | See NIAP CCEVS for additional information on NIAP. See NIST CMVP for additional information on FIPS-validated cryptographic modules. |
What is SA-4(8) Acquisition Process | Continuous Monitoring Plan for Controls? | The objective of continuous monitoring plans is to determine if the planned, required, and deployed controls within the system, system component, or system service continue to be effective over time based on the inevitable changes that occur. Developer continuous monitoring plans include a sufficient level of detail such that the information can be incorporated into continuous monitoring programs implemented by organizations. Continuous monitoring plans can include the types of control assessment and monitoring activities planned, frequency of control monitoring, and actions to be taken when controls fail or become ineffective. |
What is SA-4(9) Acquisition Process | Functions, Ports, Protocols, and Services in Use? | The identification of functions, ports, protocols, and services early in the system development life cycle (e.g., during the initial requirements definition and design stages) allows organizations to influence the design of the system, system component, or system service. This early involvement in the system development life cycle helps organizations avoid or minimize the use of functions, ports, protocols, or services that pose unnecessarily high risks and understand the trade-offs involved in blocking specific ports, protocols, or services or requiring system service providers to do so. Early identification of functions, ports, protocols, and services avoids costly retrofitting of controls after the system, component, or system service has been implemented. SA-9 describes the requirements for external system services. Organizations identify which functions, ports, protocols, and services are provided from external sources. |
What is SA-4(10) Acquisition Process | Use of Approved PIV Products? | Products on the FIPS 201-approved products list meet NIST requirements for Personal Identity Verification (PIV) of Federal Employees and Contractors. PIV cards are used for multi-factor authentication in systems and organizations. |
What is SA-4(11) Acquisition Process | System of Records? | When, by contract, an organization provides for the operation of a system of records to accomplish an organizational mission or function, the organization, consistent with its authority, causes the requirements of the PRIVACT to be applied to the system of records. |
What is SA-4(12) Acquisition Process | Data Ownership? | Contractors who operate a system that contains data owned by an organization initiating the contract have policies and procedures in place to remove the data from their systems and/or return the data in a time frame defined by the contract. |
What is SA-5 System Documentation? | System documentation helps personnel understand the implementation and operation of controls. Organizations consider establishing specific measures to determine the quality and completeness of the content provided. System documentation may be used to support the management of supply chain risk, incident response, and other functions. Personnel or roles that require documentation include system owners, system security officers, and system administrators. Attempts to obtain documentation include contacting manufacturers or suppliers and conducting web-based searches. The inability to obtain documentation may occur due to the age of the system or component or the lack of support from developers and contractors. When documentation cannot be obtained, organizations may need to recreate the documentation if it is essential to the implementation or operation of the controls. The protection provided for the documentation is commensurate with the security category or classification of the system. Documentation that addresses system vulnerabilities may require an increased level of protection. Secure operation of the system includes initially starting the system and resuming secure system operation after a lapse in system operation. |
What is SA-8 Security and Privacy Engineering Principles? | Systems security and privacy engineering principles are closely related to and implemented throughout the system development life cycle (see SA-3). Organizations can apply systems security and privacy engineering principles to new systems under development or to systems undergoing upgrades. For existing systems, organizations apply systems security and privacy engineering principles to system upgrades and modifications to the extent feasible, given the current state of hardware, software, and firmware components within those systems.
The application of systems security and privacy engineering principles helps organizations develop trustworthy, secure, and resilient systems and reduces the susceptibility to disruptions, hazards, threats, and the creation of privacy problems for individuals. Examples of system security engineering principles include: developing layered protections; establishing security and privacy policies, architecture, and controls as the foundation for design and development; incorporating security and privacy requirements into the system development life cycle; delineating physical and logical security boundaries; ensuring that developers are trained on how to build secure software; tailoring controls to meet organizational needs; and performing threat modeling to identify use cases, threat agents, attack vectors and patterns, design patterns, and compensating controls needed to mitigate risk.
Organizations that apply systems security and privacy engineering concepts and principles can facilitate the development of trustworthy, secure systems, system components, and system services; reduce risk to acceptable levels; and make informed risk management decisions. System security engineering principles can also be used to protect against certain supply chain risks, including incorporating tamper-resistant hardware into a design. |
What is SA-8(1) Security and Privacy Engineering Principles | Clear Abstractions? | The principle of clear abstractions states that a system has simple, well-defined interfaces and functions that provide a consistent and intuitive view of the data and how the data is managed. The clarity, simplicity, necessity, and sufficiency of the system interfaces— combined with a precise definition of their functional behavior—promotes ease of analysis, inspection, and testing as well as the correct and secure use of the system. The clarity of an abstraction is subjective. Examples that reflect the application of this principle include avoidance of redundant, unused interfaces; information hiding; and avoidance of semantic overloading of interfaces or their parameters. Information hiding (i.e., representation-independent programming), is a design discipline used to ensure that the internal representation of information in one system component is not visible to another system component invoking or calling the first component, such that the published abstraction is not influenced by how the data may be managed internally. |
What is SA-8(2) Security and Privacy Engineering Principles | Least Common Mechanism? | The principle of least common mechanism states that the amount of mechanism common to more than one user and depended on by all users is minimized POPEK74. Mechanism minimization implies that different components of a system refrain from using the same mechanism to access a system resource. Every shared mechanism (especially a mechanism involving shared variables) represents a potential information path between users and is designed with care to ensure that it does not unintentionally compromise security SALTZER75. Implementing the principle of least common mechanism helps to reduce the adverse consequences of sharing the system state among different programs. A single program that corrupts a shared state (including shared variables) has the potential to corrupt other programs that are dependent on the state. The principle of least common mechanism also supports the principle of simplicity of design and addresses the issue of covert storage channels LAMPSON73. |
What is SA-8(3) Security and Privacy Engineering Principles | Modularity and Layering? | The principles of modularity and layering are fundamental across system engineering disciplines. Modularity and layering derived from functional decomposition are effective in managing system complexity by making it possible to comprehend the structure of the system. Modular decomposition, or refinement in system design, is challenging and resists general statements of principle. Modularity serves to isolate functions and related data structures into well-defined logical units. Layering allows the relationships of these units to be better understood so that dependencies are clear and undesired complexity can be avoided. The security design principle of modularity extends functional modularity to include considerations based on trust, trustworthiness, privilege, and security policy. Security-informed modular decomposition includes the allocation of policies to systems in a network, separation of system applications into processes with distinct address spaces, allocation of system policies to layers, and separation of processes into subjects with distinct privileges based on hardware-supported privilege domains. |
What is SA-8(4) Security and Privacy Engineering Principles | Partially Ordered Dependencies? | The principle of partially ordered dependencies states that the synchronization, calling, and other dependencies in the system are partially ordered. A fundamental concept in system design is layering, whereby the system is organized into well-defined, functionally related modules or components. The layers are linearly ordered with respect to inter-layer dependencies, such that higher layers are dependent on lower layers. While providing functionality to higher layers, some layers can be self-contained and not dependent on lower layers. While a partial ordering of all functions in a given system may not be possible, if circular dependencies are constrained to occur within layers, the inherent problems of circularity can be more easily managed. Partially ordered dependencies and system layering contribute significantly to the simplicity and coherency of the system design. Partially ordered dependencies also facilitate system testing and analysis. |
What is SA-8(5) Security and Privacy Engineering Principles | Efficiently Mediated Access? | The principle of efficiently mediated access states that policy enforcement mechanisms utilize the least common mechanism available while satisfying stakeholder requirements within expressed constraints. The mediation of access to system resources (i.e., CPU, memory, devices, communication ports, services, infrastructure, data, and information) is often the predominant security function of secure systems. It also enables the realization of protections for the capability provided to stakeholders by the system. Mediation of resource access can result in performance bottlenecks if the system is not designed correctly. For example, by using hardware mechanisms, efficiently mediated access can be achieved. Once access to a low-level resource such as memory has been obtained, hardware protection mechanisms can ensure that out-of-bounds access does not occur. |
What is SA-8(6) Security and Privacy Engineering Principles | Minimized Sharing? | The principle of minimized sharing states that no computer resource is shared between system components (e.g., subjects, processes, functions) unless it is absolutely necessary to do so. Minimized sharing helps to simplify system design and implementation. In order to protect user-domain resources from arbitrary active entities, no resource is shared unless that sharing has been explicitly requested and granted. The need for resource sharing can be motivated by the design principle of least common mechanism in the case of internal entities or driven by stakeholder requirements. However, internal sharing is carefully designed to avoid performance and covert storage and timing channel problems. Sharing via common mechanism can increase the susceptibility of data and information to unauthorized access, disclosure, use, or modification and can adversely affect the inherent capability provided by the system. To minimize sharing induced by common mechanisms, such mechanisms can be designed to be reentrant or virtualized to preserve separation. Moreover, the use of global data to share information is carefully scrutinized. The lack of encapsulation may obfuscate relationships among the sharing entities. |
What is SA-8(7) Security and Privacy Engineering Principles | Reduced Complexity? | The principle of reduced complexity states that the system design is as simple and small as possible. A small and simple design is more understandable, more analyzable, and less prone to error. The reduced complexity principle applies to any aspect of a system, but it has particular importance for security due to the various analyses performed to obtain evidence about the emergent security property of the system. For such analyses to be successful, a small and simple design is essential. Application of the principle of reduced complexity contributes to the ability of system developers to understand the correctness and completeness of system security functions. It also facilitates the identification of potential vulnerabilities. The corollary of reduced complexity states that the simplicity of the system is directly related to the number of vulnerabilities it will contain; that is, simpler systems contain fewer vulnerabilities. An benefit of reduced complexity is that it is easier to understand whether the intended security policy has been captured in the system design and that fewer vulnerabilities are likely to be introduced during engineering development. An additional benefit is that any such conclusion about correctness, completeness, and the existence of vulnerabilities can be reached with a higher degree of assurance in contrast to conclusions reached in situations where the system design is inherently more complex. Transitioning from older technologies to newer technologies (e.g., transitioning from IPv4 to IPv6) may require implementing the older and newer technologies simultaneously during the transition period. This may result in a temporary increase in system complexity during the transition. |
What is SA-8(8) Security and Privacy Engineering Principles | Secure Evolvability? | The principle of secure evolvability states that a system is developed to facilitate the maintenance of its security properties when there are changes to the system’s structure, interfaces, interconnections (i.e., system architecture), functionality, or configuration (i.e., security policy enforcement). Changes include a new, enhanced, or upgraded system capability; maintenance and sustainment activities; and reconfiguration. Although it is not possible to plan for every aspect of system evolution, system upgrades and changes can be anticipated by analyses of mission or business strategic direction, anticipated changes in the threat environment, and anticipated maintenance and sustainment needs. It is unrealistic to expect that complex systems remain secure in contexts not envisioned during development, whether such contexts are related to the operational environment or to usage. A system may be secure in some new contexts, but there is no guarantee that its emergent behavior will always be secure. It is easier to build trustworthiness into a system from the outset, and it follows that the sustainment of system trustworthiness requires planning for change as opposed to adapting in an ad hoc or non-methodical manner. The benefits of this principle include reduced vendor life cycle costs, reduced cost of ownership, improved system security, more effective management of security risk, and less risk uncertainty. |
What is SA-8(9) Security and Privacy Engineering Principles | Trusted Components? | The principle of trusted components states that a component is trustworthy to at least a level commensurate with the security dependencies it supports (i.e., how much it is trusted to perform its security functions by other components). This principle enables the composition of components such that trustworthiness is not inadvertently diminished and the trust is not consequently misplaced. Ultimately, this principle demands some metric by which the trust in a component and the trustworthiness of a component can be measured on the same abstract scale. The principle of trusted components is particularly relevant when considering systems and components in which there are complex chains of trust dependencies. A trust dependency is also referred to as a trust relationship and there may be chains of trust relationships.
The principle of trusted components also applies to a compound component that consists of subcomponents (e.g., a subsystem), which may have varying levels of trustworthiness. The conservative assumption is that the trustworthiness of a compound component is that of its least trustworthy subcomponent. It may be possible to provide a security engineering rationale that the trustworthiness of a particular compound component is greater than the conservative assumption. However, any such rationale reflects logical reasoning based on a clear statement of the trustworthiness objectives as well as relevant and credible evidence. The trustworthiness of a compound component is not the same as increased application of defense-in-depth layering within the component or a replication of components. Defense-in-depth techniques do not increase the trustworthiness of the whole above that of the least trustworthy component. |
What is SA-8(10) Security and Privacy Engineering Principles | Hierarchical Trust? | The principle of hierarchical trust for components builds on the principle of trusted components and states that the security dependencies in a system will form a partial ordering if they preserve the principle of trusted components. The partial ordering provides the basis for trustworthiness reasoning or an assurance case (assurance argument) when composing a secure system from heterogeneously trustworthy components. To analyze a system composed of heterogeneously trustworthy components for its trustworthiness, it is essential to eliminate circular dependencies with regard to the trustworthiness. If a more trustworthy component located in a lower layer of the system were to depend on a less trustworthy component in a higher layer, this would, in effect, put the components in the same less trustworthy equivalence class per the principle of trusted components. Trust relationships, or chains of trust, can have various manifestations. For example, the root certificate of a certificate hierarchy is the most trusted node in the hierarchy, whereas the leaves in the hierarchy may be the least trustworthy nodes. Another example occurs in a layered high-assurance system where the security kernel (including the hardware base), which is located at the lowest layer of the system, is the most trustworthy component. The principle of hierarchical trust, however, does not prohibit the use of overly trustworthy components. There may be cases in a system of low trustworthiness where it is reasonable to employ a highly trustworthy component rather than one that is less trustworthy (e.g., due to availability or other cost-benefit driver). For such a case, any dependency of the highly trustworthy component upon a less trustworthy component does not degrade the trustworthiness of the resulting low-trust system. |
What is SA-8(11) Security and Privacy Engineering Principles | Inverse Modification Threshold? | The principle of inverse modification threshold builds on the principle of trusted components and the principle of hierarchical trust and states that the degree of protection provided to a component is commensurate with its trustworthiness. As the trust placed in a component increases, the protection against unauthorized modification of the component also increases to the same degree. Protection from unauthorized modification can come in the form of the component’s own self-protection and innate trustworthiness, or it can come from the protections afforded to the component from other elements or attributes of the security architecture (to include protections in the environment of operation). |
What is SA-8(12) Security and Privacy Engineering Principles | Hierarchical Protection? | The principle of hierarchical protection states that a component need not be protected from more trustworthy components. In the degenerate case of the most trusted component, it protects itself from all other components. For example, if an operating system kernel is deemed the most trustworthy component in a system, then it protects itself from all untrusted applications it supports, but the applications, conversely, do not need to protect themselves from the kernel. The trustworthiness of users is a consideration for applying the principle of hierarchical protection. A trusted system need not protect itself from an equally trustworthy user, reflecting use of untrusted systems in system high environments where users are highly trustworthy and where other protections are put in place to bound and protect the system high execution environment. |
What is SA-8(13) Security and Privacy Engineering Principles | Minimized Security Elements? | The principle of minimized security elements states that the system does not have extraneous trusted components. The principle of minimized security elements has two aspects: the overall cost of security analysis and the complexity of security analysis. Trusted components are generally costlier to construct and implement, owing to the increased rigor of development processes. Trusted components require greater security analysis to qualify their trustworthiness. Thus, to reduce the cost and decrease the complexity of the security analysis, a system contains as few trustworthy components as possible. The analysis of the interaction of trusted components with other components of the system is one of the most important aspects of system security verification. If the interactions between components are unnecessarily complex, the security of the system will also be more difficult to ascertain than one whose internal trust relationships are simple and elegantly constructed. In general, fewer trusted components result in fewer internal trust relationships and a simpler system. |
What is SA-8(14) Security and Privacy Engineering Principles | Least Privilege? | The principle of least privilege states that each system component is allocated sufficient privileges to accomplish its specified functions but no more. Applying the principle of least privilege limits the scope of the component’s actions, which has two desirable effects: the security impact of a failure, corruption, or misuse of the component will have a minimized security impact, and the security analysis of the component will be simplified. Least privilege is a pervasive principle that is reflected in all aspects of the secure system design. Interfaces used to invoke component capability are available to only certain subsets of the user population, and component design supports a sufficiently fine granularity of privilege decomposition. For example, in the case of an audit mechanism, there may be an interface for the audit manager, who configures the audit settings; an interface for the audit operator, who ensures that audit data is safely collected and stored; and, finally, yet another interface for the audit reviewer, who only has need to view the audit data that has been collected but no need to perform operations on that data.
In addition to its manifestations at the system interface, least privilege can be used as a guiding principle for the internal structure of the system itself. One aspect of internal least privilege is to construct modules so that only the elements encapsulated by the module are directly operated on by the functions within the module. Elements external to a module that may be affected by the module’s operation are indirectly accessed through interaction (e.g., via a function call) with the module that contains those elements. Another aspect of internal least privilege is that the scope of a given module or component includes only those system elements that are necessary for its functionality and that the access modes for the elements (e.g., read, write) are minimal. |
What is SA-8(15) Security and Privacy Engineering Principles | Predicate Permission? | The principle of predicate permission states that system designers consider requiring multiple authorized entities to provide consent before a highly critical operation or access to highly sensitive data, information, or resources is allowed to proceed. SALTZER75 originally named predicate permission the separation of privilege. It is also equivalent to separation of duty. The division of privilege among multiple parties decreases the likelihood of abuse and provides the safeguard that no single accident, deception, or breach of trust is sufficient to enable an unrecoverable action that can lead to significantly damaging effects. The design options for such a mechanism may require simultaneous action (e.g., the firing of a nuclear weapon requires two different authorized individuals to give the correct command within a small time window) or a sequence of operations where each successive action is enabled by some prior action, but no single individual is able to enable more than one action. |
What is SA-8(16) Security and Privacy Engineering Principles | Self-reliant Trustworthiness? | The principle of self-reliant trustworthiness states that systems minimize their reliance on other systems for their own trustworthiness. A system is trustworthy by default, and any connection to an external entity is used to supplement its function. If a system were required to maintain a connection with another external entity in order to maintain its trustworthiness, then that system would be vulnerable to malicious and non-malicious threats that could result in the loss or degradation of that connection. The benefit of the principle of self-reliant trustworthiness is that the isolation of a system will make it less vulnerable to attack. A corollary to this principle relates to the ability of the system (or system component) to operate in isolation and then resynchronize with other components when it is rejoined with them. |
What is SA-8(17) Security and Privacy Engineering Principles | Secure Distributed Composition? | The principle of secure distributed composition states that the composition of distributed components that enforce the same system security policy result in a system that enforces that policy at least as well as the individual components do. Many of the design principles for secure systems deal with how components can or should interact. The need to create or enable a capability from the composition of distributed components can magnify the relevancy of these principles. In particular, the translation of security policy from a stand-alone to a distributed system or a system-of-systems can have unexpected or emergent results. Communication protocols and distributed data consistency mechanisms help to ensure consistent policy enforcement across a distributed system. To ensure a system-wide level of assurance of correct policy enforcement, the security architecture of a distributed composite system is thoroughly analyzed. |
What is SA-8(18) Security and Privacy Engineering Principles | Trusted Communications Channels? | The principle of trusted communication channels states that when composing a system where there is a potential threat to communications between components (i.e., the interconnections between components), each communication channel is trustworthy to a level commensurate with the security dependencies it supports (i.e., how much it is trusted by other components to perform its security functions). Trusted communication channels are achieved by a combination of restricting access to the communication channel (to ensure an acceptable match in the trustworthiness of the endpoints involved in the communication) and employing end-to-end protections for the data transmitted over the communication channel (to protect against interception and modification and to further increase the assurance of proper end-to-end communication). |
What is SA-8(19) Security and Privacy Engineering Principles | Continuous Protection? | The principle of continuous protection states that components and data used to enforce the security policy have uninterrupted protection that is consistent with the security policy and the security architecture assumptions. No assurances that the system can provide the confidentiality, integrity, availability, and privacy protections for its design capability can be made if there are gaps in the protection. Any assurances about the ability to secure a delivered capability require that data and information are continuously protected. That is, there are no periods during which data and information are left unprotected while under control of the system (i.e., during the creation, storage, processing, or communication of the data and information, as well as during system initialization, execution, failure, interruption, and shutdown). Continuous protection requires adherence to the precepts of the reference monitor concept (i.e., every request is validated by the reference monitor; the reference monitor is able to protect itself from tampering; and sufficient assurance of the correctness and completeness of the mechanism can be ascertained from analysis and testing) and the principle of secure failure and recovery (i.e., preservation of a secure state during error, fault, failure, and successful attack; preservation of a secure state during recovery to normal, degraded, or alternative operational modes).
Continuous protection also applies to systems designed to operate in varying configurations, including those that deliver full operational capability and degraded-mode configurations that deliver partial operational capability. The continuous protection principle requires that changes to the system security policies be traceable to the operational need that drives the configuration and be verifiable (i.e., it is possible to verify that the proposed changes will not put the system into an insecure state). Insufficient traceability and verification may lead to inconsistent states or protection discontinuities due to the complex or undecidable nature of the problem. The use of pre-verified configuration definitions that reflect the new security policy enables analysis to determine that a transition from old to new policies is essentially atomic and that any residual effects from the old policy are guaranteed to not conflict with the new policy. The ability to demonstrate continuous protection is rooted in the clear articulation of life cycle protection needs as stakeholder security requirements. |
What is SA-8(20) Security and Privacy Engineering Principles | Secure Metadata Management? | The principle of secure metadata management states that metadata are first class objects with respect to security policy when the policy requires either complete protection of information or that the security subsystem be self-protecting. The principle of secure metadata management is driven by the recognition that a system, subsystem, or component cannot achieve self-protection unless it protects the data it relies on for correct execution. Data is generally not interpreted by the system that stores it. It may have semantic value (i.e., it comprises information) to users and programs that process the data. In contrast, metadata is information about data, such as a file name or the date when the file was created. Metadata is bound to the target data that it describes in a way that the system can interpret, but it need not be stored inside of or proximate to its target data. There may be metadata whose target is itself metadata (e.g., the classification level or impact level of a file name), including self-referential metadata.
The apparent secondary nature of metadata can lead to neglect of its legitimate need for protection, resulting in a violation of the security policy that includes the exfiltration of information. A particular concern associated with insufficient protections for metadata is associated with multilevel secure (MLS) systems. MLS systems mediate access by a subject to an object based on relative sensitivity levels. It follows that all subjects and objects in the scope of control of the MLS system are either directly labeled or indirectly attributed with sensitivity levels. The corollary of labeled metadata for MLS systems states that objects containing metadata are labeled. As with protection needs assessments for data, attention is given to ensure that the confidentiality and integrity protections are individually assessed, specified, and allocated to metadata, as would be done for mission, business, and system data. |
What is SA-8(21) Security and Privacy Engineering Principles | Self-analysis? | The principle of self-analysis states that a system component is able to assess its internal state and functionality to a limited extent at various stages of execution, and that this self-analysis capability is commensurate with the level of trustworthiness invested in the system. At the system level, self-analysis can be achieved through hierarchical assessments of trustworthiness established in a bottom-up fashion. In this approach, the lower-level components check for data integrity and correct functionality (to a limited extent) of higher-level components. For example, trusted boot sequences involve a trusted lower-level component that attests to the trustworthiness of the next higher-level components so that a transitive chain of trust can be established. At the root, a component attests to itself, which usually involves an axiomatic or environmentally enforced assumption about its integrity. Results of the self-analyses can be used to guard against externally induced errors, internal malfunction, or transient errors. By following this principle, some simple malfunctions or errors can be detected without allowing the effects of the error or malfunction to propagate outside of the component. Further, the self-test can be used to attest to the configuration of the component, detecting any potential conflicts in configuration with respect to the expected configuration. |
What is SA-8(22) Security and Privacy Engineering Principles | Accountability and Traceability? | The principle of accountability and traceability states that it is possible to trace security-relevant actions (i.e., subject-object interactions) to the entity on whose behalf the action is being taken. The principle of accountability and traceability requires a trustworthy infrastructure that can record details about actions that affect system security (e.g., an audit subsystem). To record the details about actions, the system is able to uniquely identify the entity on whose behalf the action is being carried out and also record the relevant sequence of actions that are carried out. The accountability policy also requires that audit trail itself be protected from unauthorized access and modification. The principle of least privilege assists in tracing the actions to particular entities, as it increases the granularity of accountability. Associating specific actions with system entities, and ultimately with users, and making the audit trail secure against unauthorized access and modifications provide non-repudiation because once an action is recorded, it is not possible to change the audit trail. Another important function that accountability and traceability serves is in the routine and forensic analysis of events associated with the violation of security policy. Analysis of audit logs may provide additional information that may be helpful in determining the path or component that allowed the violation of the security policy and the actions of individuals associated with the violation of the security policy. |
What is SA-8(23) Security and Privacy Engineering Principles | Secure Defaults? | The principle of secure defaults states that the default configuration of a system (including its constituent subsystems, components, and mechanisms) reflects a restrictive and conservative enforcement of security policy. The principle of secure defaults applies to the initial (i.e., default) configuration of a system as well as to the security engineering and design of access control and other security functions that follow a deny unless explicitly authorized strategy. The initial configuration aspect of this principle requires that any as shipped configuration of a system, subsystem, or system component does not aid in the violation of the security policy and can prevent the system from operating in the default configuration for those cases where the security policy itself requires configuration by the operational user.
Restrictive defaults mean that the system will operate as-shipped with adequate self-protection and be able to prevent security breaches before the intended security policy and system configuration is established. In cases where the protection provided by the as-shipped product is inadequate, stakeholders assess the risk of using it prior to establishing a secure initial state. Adherence to the principle of secure defaults guarantees that a system is established in a secure state upon successfully completing initialization. In situations where the system fails to complete initialization, either it will perform a requested operation using secure defaults or it will not perform the operation. Refer to the principles of continuous protection and secure failure and recovery that parallel this principle to provide the ability to detect and recover from failure.
The security engineering approach to this principle states that security mechanisms deny requests unless the request is found to be well-formed and consistent with the security policy. The insecure alternative is to allow a request unless it is shown to be inconsistent with the policy. In a large system, the conditions that are satisfied to grant a request that is denied by default are often far more compact and complete than those that would need to be checked in order to deny a request that is granted by default. |
What is SA-8(24) Security and Privacy Engineering Principles | Secure Failure and Recovery? | The principle of secure failure and recovery states that neither a failure in a system function or mechanism nor any recovery action in response to failure leads to a violation of security policy. The principle of secure failure and recovery parallels the principle of continuous protection to ensure that a system is capable of detecting (within limits) actual and impending failure at any stage of its operation (i.e., initialization, normal operation, shutdown, and maintenance) and to take appropriate steps to ensure that security policies are not violated. In addition, when specified, the system is capable of recovering from impending or actual failure to resume normal, degraded, or alternative secure operations while ensuring that a secure state is maintained such that security policies are not violated.
Failure is a condition in which the behavior of a component deviates from its specified or expected behavior for an explicitly documented input. Once a failed security function is detected, the system may reconfigure itself to circumvent the failed component while maintaining security and provide all or part of the functionality of the original system, or it may completely shut itself down to prevent any further violation of security policies. For this to occur, the reconfiguration functions of the system are designed to ensure continuous enforcement of security policy during the various phases of reconfiguration.
Another technique that can be used to recover from failures is to perform a rollback to a secure state (which may be the initial state) and then either shutdown or replace the service or component that failed such that secure operations may resume. Failure of a component may or may not be detectable to the components using it. The principle of secure failure indicates that components fail in a state that denies rather than grants access. For example, a nominally atomic operation interrupted before completion does not violate security policy and is designed to handle interruption events by employing higher-level atomicity and rollback mechanisms (e.g., transactions). If a service is being used, its atomicity properties are well-documented and characterized so that the component availing itself of that service can detect and handle interruption events appropriately. For example, a system is designed to gracefully respond to disconnection and support resynchronization and data consistency after disconnection.
Failure protection strategies that employ replication of policy enforcement mechanisms, sometimes called defense in depth, can allow the system to continue in a secure state even when one mechanism has failed to protect the system. If the mechanisms are similar, however, the additional protection may be illusory, as the adversary can simply attack in series. Similarly, in a networked system, breaking the security on one system or service may enable an attacker to do the same on other similar replicated systems and services. By employing multiple protection mechanisms whose features are significantly different, the possibility of attack replication or repetition can be reduced. Analyses are conducted to weigh the costs and benefits of such redundancy techniques against increased resource usage and adverse effects on the overall system performance. Additional analyses are conducted as the complexity of these mechanisms increases, as could be the case for dynamic behaviors. Increased complexity generally reduces trustworthiness. When a resource cannot be continuously protected, it is critical to detect and repair any security breaches before the resource is once again used in a secure context. |
What is SA-8(25) Security and Privacy Engineering Principles | Economic Security? | The principle of economic security states that security mechanisms are not costlier than the potential damage that could occur from a security breach. This is the security-relevant form of the cost-benefit analyses used in risk management. The cost assumptions of cost-benefit analysis prevent the system designer from incorporating security mechanisms of greater strength than necessary, where strength of mechanism is proportional to cost. The principle of economic security also requires analysis of the benefits of assurance relative to the cost of that assurance in terms of the effort expended to obtain relevant and credible evidence as well as the necessary analyses to assess and draw trustworthiness and risk conclusions from the evidence. |
What is SA-8(26) Security and Privacy Engineering Principles | Performance Security? | The principle of performance security states that security mechanisms are constructed so that they do not degrade system performance unnecessarily. Stakeholder and system design requirements for performance and security are precisely articulated and prioritized. For the system implementation to meet its design requirements and be found acceptable to stakeholders (i.e., validation against stakeholder requirements), the designers adhere to the specified constraints that capability performance needs place on protection needs. The overall impact of computationally intensive security services (e.g., cryptography) are assessed and demonstrated to pose no significant impact to higher-priority performance considerations or are deemed to provide an acceptable trade-off of performance for trustworthy protection. The trade-off considerations include less computationally intensive security services unless they are unavailable or insufficient. The insufficiency of a security service is determined by functional capability and strength of mechanism. The strength of mechanism is selected with respect to security requirements, performance-critical overhead issues (e.g., cryptographic key management), and an assessment of the capability of the threat.
The principle of performance security leads to the incorporation of features that help in the enforcement of security policy but incur minimum overhead, such as low-level hardware mechanisms upon which higher-level services can be built. Such low-level mechanisms are usually very specific, have very limited functionality, and are optimized for performance. For example, once access rights to a portion of memory is granted, many systems use hardware mechanisms to ensure that all further accesses involve the correct memory address and access mode. Application of this principle reinforces the need to design security into the system from the ground up and to incorporate simple mechanisms at the lower layers that can be used as building blocks for higher-level mechanisms. |
What is SA-8(27) Security and Privacy Engineering Principles | Human Factored Security? | The principle of human factored security states that the user interface for security functions and supporting services is intuitive, user-friendly, and provides feedback for user actions that affect such policy and its enforcement. The mechanisms that enforce security policy are not intrusive to the user and are designed not to degrade user efficiency. Security policy enforcement mechanisms also provide the user with meaningful, clear, and relevant feedback and warnings when insecure choices are being made. Particular attention is given to interfaces through which personnel responsible for system administration and operation configure and set up the security policies. Ideally, these personnel are able to understand the impact of their choices. Personnel with system administrative and operational responsibilities are able to configure systems before start-up and administer them during runtime with confidence that their intent is correctly mapped to the system’s mechanisms. Security services, functions, and mechanisms do not impede or unnecessarily complicate the intended use of the system. There is a trade-off between system usability and the strictness necessary for security policy enforcement. If security mechanisms are frustrating or difficult to use, then users may disable them, avoid them, or use them in ways inconsistent with the security requirements and protection needs that the mechanisms were designed to satisfy. |
What is SA-8(28) Security and Privacy Engineering Principles | Acceptable Security? | The principle of acceptable security requires that the level of privacy and performance that the system provides is consistent with the users’ expectations. The perception of personal privacy may affect user behavior, morale, and effectiveness. Based on the organizational privacy policy and the system design, users should be able to restrict their actions to protect their privacy. When systems fail to provide intuitive interfaces or meet privacy and performance expectations, users may either choose to completely avoid the system or use it in ways that may be inefficient or even insecure. |
What is SA-8(29) Security and Privacy Engineering Principles | Repeatable and Documented Procedures? | The principle of repeatable and documented procedures states that the techniques and methods employed to construct a system component permit the same component to be completely and correctly reconstructed at a later time. Repeatable and documented procedures support the development of a component that is identical to the component created earlier, which may be in widespread use. In the case of other system artifacts (e.g., documentation and testing results), repeatability supports consistency and the ability to inspect the artifacts. Repeatable and documented procedures can be introduced at various stages within the system development life cycle and contribute to the ability to evaluate assurance claims for the system. Examples include systematic procedures for code development and review, procedures for the configuration management of development tools and system artifacts, and procedures for system delivery. |
What is SA-8(30) Security and Privacy Engineering Principles | Procedural Rigor? | The principle of procedural rigor states that the rigor of a system life cycle process is commensurate with its intended trustworthiness. Procedural rigor defines the scope, depth, and detail of the system life cycle procedures. Rigorous system life cycle procedures contribute to the assurance that the system is correct and free of unintended functionality in several ways. First, the procedures impose checks and balances on the life cycle process such that the introduction of unspecified functionality is prevented.
Second, rigorous procedures applied to systems security engineering activities that produce specifications and other system design documents contribute to the ability to understand the system as it has been built rather than trusting that the component, as implemented, is the authoritative (and potentially misleading) specification.
Finally, modifications to an existing system component are easier when there are detailed specifications that describe its current design instead of studying source code or schematics to try to understand how it works. Procedural rigor helps ensure that security functional and assurance requirements have been satisfied, and it contributes to a better-informed basis for the determination of trustworthiness and risk posture. Procedural rigor is commensurate with the degree of assurance desired for the system. If the required trustworthiness of the system is low, a high level of procedural rigor may add unnecessary cost, whereas when high trustworthiness is critical, the cost of high procedural rigor is merited. |
What is SA-8(31) Security and Privacy Engineering Principles | Secure System Modification? | The principle of secure system modification states that system modification maintains system security with respect to the security requirements and risk tolerance of stakeholders. Upgrades or modifications to systems can transform secure systems into systems that are not secure. The procedures for system modification ensure that if the system is to maintain its trustworthiness, the same rigor that was applied to its initial development is applied to any system changes. Because modifications can affect the ability of the system to maintain its secure state, a careful security analysis of the modification is needed prior to its implementation and deployment. This principle parallels the principle of secure evolvability. |
What is SA-8(32) Security and Privacy Engineering Principles | Sufficient Documentation? | The principle of sufficient documentation states that organizational personnel with responsibilities to interact with the system are provided with adequate documentation and other information such that the personnel contribute to rather than detract from system security. Despite attempts to comply with principles such as human factored security and acceptable security, systems are inherently complex, and the design intent for the use of security mechanisms and the ramifications of the misuse or misconfiguration of security mechanisms are not always intuitively obvious. Uninformed and insufficiently trained users can introduce vulnerabilities due to errors of omission and commission. The availability of documentation and training can help to ensure a knowledgeable cadre of personnel, all of whom have a critical role in the achievement of principles such as continuous protection. Documentation is written clearly and supported by training that provides security awareness and understanding of security-relevant responsibilities. |
What is SA-8(33) Security and Privacy Engineering Principles | Minimization? | The principle of minimization states that organizations should only process personally identifiable information that is directly relevant and necessary to accomplish an authorized purpose and should only maintain personally identifiable information for as long as is necessary to accomplish the purpose. Organizations have processes in place, consistent with applicable laws and policies, to implement the principle of minimization. |
What is SA-9 External System Services? | External system services are provided by an external provider, and the organization has no direct control over the implementation of the required controls or the assessment of control effectiveness. Organizations establish relationships with external service providers in a variety of ways, including through business partnerships, contracts, interagency agreements, lines of business arrangements, licensing agreements, joint ventures, and supply chain exchanges. The responsibility for managing risks from the use of external system services remains with authorizing officials. For services external to organizations, a chain of trust requires that organizations establish and retain a certain level of confidence that each provider in the consumer-provider relationship provides adequate protection for the services rendered. The extent and nature of this chain of trust vary based on relationships between organizations and the external providers. Organizations document the basis for the trust relationships so that the relationships can be monitored. External system services documentation includes government, service providers, end user security roles and responsibilities, and service-level agreements. Service-level agreements define the expectations of performance for implemented controls, describe measurable outcomes, and identify remedies and response requirements for identified instances of noncompliance. |
What is SA-9(1) External System Services | Risk Assessments and Organizational Approvals? | Information security services include the operation of security devices, such as firewalls or key management services as well as incident monitoring, analysis, and response. Risks assessed can include system, mission or business, security, privacy, or supply chain risks. |
What is SA-9(2) External System Services | Identification of Functions, Ports, Protocols, and Services? | Information from external service providers regarding the specific functions, ports, protocols, and services used in the provision of such services can be useful when the need arises to understand the trade-offs involved in restricting certain functions and services or blocking certain ports and protocols. |
What is SA-9(3) External System Services | Establish and Maintain Trust Relationship with Providers? | Trust relationships between organizations and external service providers reflect the degree of confidence that the risk from using external services is at an acceptable level. Trust relationships can help organizations gain increased levels of confidence that service providers are providing adequate protection for the services rendered and can also be useful when conducting incident response or when planning for upgrades or obsolescence. Trust relationships can be complicated due to the potentially large number of entities participating in the consumer-provider interactions, subordinate relationships and levels of trust, and types of interactions between the parties. In some cases, the degree of trust is based on the level of control that organizations can exert on external service providers regarding the controls necessary for the protection of the service, information, or individual privacy and the evidence brought forth as to the effectiveness of the implemented controls. The level of control is established by the terms and conditions of the contracts or service-level agreements. |
What is SA-9(4) External System Services | Consistent Interests of Consumers and Providers? | As organizations increasingly use external service providers, it is possible that the interests of the service providers may diverge from organizational interests. In such situations, simply having the required technical, management, or operational controls in place may not be sufficient if the providers that implement and manage those controls are not operating in a manner consistent with the interests of the consuming organizations. Actions that organizations take to address such concerns include requiring background checks for selected service provider personnel; examining ownership records; employing only trustworthy service providers, such as providers with which organizations have had successful trust relationships; and conducting routine, periodic, unscheduled visits to service provider facilities. |
What is SA-9(5) External System Services | Processing, Storage, and Service Location? | The location of information processing, information and data storage, or system services can have a direct impact on the ability of organizations to successfully execute their mission and business functions. The impact occurs when external providers control the location of processing, storage, or services. The criteria that external providers use for the selection of processing, storage, or service locations may be different from the criteria that organizations use. For example, organizations may desire that data or information storage locations be restricted to certain locations to help facilitate incident response activities in case of information security incidents or breaches. Incident response activities, including forensic analyses and after-the-fact investigations, may be adversely affected by the governing laws, policies, or protocols in the locations where processing and storage occur and/or the locations from which system services emanate. |
What is SA-9(6) External System Services | Organization-controlled Cryptographic Keys? | Maintaining exclusive control of cryptographic keys in an external system prevents decryption of organizational data by external system staff. Organizational control of cryptographic keys can be implemented by encrypting and decrypting data inside the organization as data is sent to and received from the external system or by employing a component that permits encryption and decryption functions to be local to the external system but allows exclusive organizational access to the encryption keys. |
What is SA-9(7) External System Services | Organization-controlled Integrity Checking? | Storage of organizational information in an external system could limit visibility into the security status of its data. The ability of the organization to verify and validate the integrity of its stored data without transferring it out of the external system provides such visibility. |
What is SA-9(8) External System Services | Processing and Storage Location — U.S. Jurisdiction? | The geographic location of information processing and data storage can have a direct impact on the ability of organizations to successfully execute their mission and business functions. A compromise or breach of high impact information and systems can have severe or catastrophic adverse impacts on organizational assets and operations, individuals, other organizations, and the Nation. Restricting the processing and storage of high-impact information to facilities within the legal jurisdictional boundary of the United States provides greater control over such processing and storage. |
What is SA-10 Developer Configuration Management? | Organizations consider the quality and completeness of configuration management activities conducted by developers as direct evidence of applying effective security controls. Controls include protecting the master copies of material used to generate security-relevant portions of the system hardware, software, and firmware from unauthorized modification or destruction. Maintaining the integrity of changes to the system, system component, or system service requires strict configuration control throughout the system development life cycle to track authorized changes and prevent unauthorized changes.
The configuration items that are placed under configuration management include the formal model; the functional, high-level, and low-level design specifications; other design data; implementation documentation; source code and hardware schematics; the current running version of the object code; tools for comparing new versions of security-relevant hardware descriptions and source code with previous versions; and test fixtures and documentation. Depending on the mission and business needs of organizations and the nature of the contractual relationships in place, developers may provide configuration management support during the operations and maintenance stage of the system development life cycle. |
What is SA-10(1) Developer Configuration Management | Software and Firmware Integrity Verification? | Software and firmware integrity verification allows organizations to detect unauthorized changes to software and firmware components using developer-provided tools, techniques, and mechanisms. The integrity checking mechanisms can also address counterfeiting of software and firmware components. Organizations verify the integrity of software and firmware components, for example, through secure one-way hashes provided by developers. Delivered software and firmware components also include any updates to such components. |
What is SA-10(2) Developer Configuration Management | Alternative Configuration Management Processes? | Alternate configuration management processes may be required when organizations use commercial off-the-shelf information technology products. Alternate configuration management processes include organizational personnel who review and approve proposed changes to systems, system components, and system services and conduct security and privacy impact analyses prior to the implementation of changes to systems, components, or services. |
What is SA-10(3) Developer Configuration Management | Hardware Integrity Verification? | Hardware integrity verification allows organizations to detect unauthorized changes to hardware components using developer-provided tools, techniques, methods, and mechanisms. Organizations may verify the integrity of hardware components with hard-to-copy labels, verifiable serial numbers provided by developers, and by requiring the use of anti-tamper technologies. Delivered hardware components also include hardware and firmware updates to such components. |