NIST System and Communications Protection Risk Controls (sc)

Policy and Procedures (sc-1)

Develop, document, and disseminate to organization-defined personnel or roles:

one or more,Organization-level,Mission/business process-level,System-level system and communications protection policy that:

Addresses purpose, scope, roles, responsibilities, management commitment, coordination among organizational entities, and compliance; and

Is consistent with applicable laws, executive orders, directives, regulations, policies, standards, and guidelines; and

Procedures to facilitate the implementation of the system and communications protection policy and the associated system and communications protection controls;

Designate an organization-defined official to manage the development, documentation, and dissemination of the system and communications protection policy and procedures; and

Review and update the current system and communications protection:

Policy organization-defined frequency and following organization-defined events; and

Procedures organization-defined frequency and following organization-defined events.

System and communications protection policy and procedures address the controls in the SC 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 communications protection 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 communications protection policy and procedures include assessment or audit findings, security incidents or breaches, or changes in applicable laws, executive orders, directives, regulations, policies, standards, and guidelines. Simply restating controls does not constitute an organizational policy or procedure.

Separation of System and User Functionality (sc-2)

Separate user functionality, including user interface services, from system management functionality.

System management functionality includes functions that are necessary to administer databases, network components, workstations, or servers. These functions typically require privileged user access. The separation of user functions from system management functions is physical or logical. Organizations may separate system management functions from user functions by using different computers, instances of operating systems, central processing units, or network addresses; by employing virtualization techniques; or some combination of these or other methods. Separation of system management functions from user functions includes web administrative interfaces that employ separate authentication methods for users of any other system resources. Separation of system and user functions may include isolating administrative interfaces on different domains and with additional access controls. The separation of system and user functionality can be achieved by applying the systems security engineering design principles in #sa-8(#sa-8), including [SA-8(1)](#sa-8.1), [SA-8(3)](#sa-8.3), [SA-8(4)](#sa-8.4), [SA-8(10)](#sa-8.10), [SA-8(12)](#sa-8.12), [SA-8(13)](#sa-8.13), [SA-8(14)](#sa-8.14), and [SA-8(18)](#sa-8.18).

Security Function Isolation (sc-3)

Isolate security functions from nonsecurity functions.

Security functions are isolated from nonsecurity functions by means of an isolation boundary implemented within a system via partitions and domains. The isolation boundary controls access to and protects the integrity of the hardware, software, and firmware that perform system security functions. Systems implement code separation in many ways, such as through the provision of security kernels via processor rings or processor modes. For non-kernel code, security function isolation is often achieved through file system protections that protect the code on disk and address space protections that protect executing code. Systems can restrict access to security functions using access control mechanisms and by implementing least privilege capabilities. While the ideal is for all code within the defined security function isolation boundary to only contain security-relevant code, it is sometimes necessary to include nonsecurity functions as an exception. The isolation of security functions from nonsecurity functions can be achieved by applying the systems security engineering design principles in #sa-8(#sa-8), including [SA-8(1)](#sa-8.1), [SA-8(3)](#sa-8.3), [SA-8(4)](#sa-8.4), [SA-8(10)](#sa-8.10), [SA-8(12)](#sa-8.12), [SA-8(13)](#sa-8.13), [SA-8(14)](#sa-8.14), and [SA-8(18)](#sa-8.18).

Information in Shared System Resources (sc-4)

Prevent unauthorized and unintended information transfer via shared system resources.

Preventing unauthorized and unintended information transfer via shared system resources stops information produced by the actions of prior users or roles (or the actions of processes acting on behalf of prior users or roles) from being available to current users or roles (or current processes acting on behalf of current users or roles) that obtain access to shared system resources after those resources have been released back to the system. Information in shared system resources also applies to encrypted representations of information. In other contexts, control of information in shared system resources is referred to as object reuse and residual information protection. Information in shared system resources does not address information remanence, which refers to the residual representation of data that has been nominally deleted; covert channels (including storage and timing channels), where shared system resources are manipulated to violate information flow restrictions; or components within systems for which there are only single users or roles.

Denial-of-service Protection (sc-5)

Protect against,Limit the effects of the following types of denial-of-service events: organization-defined types of denial-of-service events; and

Employ the following controls to achieve the denial-of-service objective: organization-defined controls by type of denial-of-service event.

Denial-of-service events may occur due to a variety of internal and external causes, such as an attack by an adversary or a lack of planning to support organizational needs with respect to capacity and bandwidth. Such attacks can occur across a wide range of network protocols (e.g., IPv4, IPv6). A variety of technologies are available to limit or eliminate the origination and effects of denial-of-service events. For example, boundary protection devices can filter certain types of packets to protect system components on internal networks from being directly affected by or the source of denial-of-service attacks. Employing increased network capacity and bandwidth combined with service redundancy also reduces the susceptibility to denial-of-service events.

Resource Availability (sc-6)

Protect the availability of resources by allocating organization-defined resources by one or more,priority,quota, organization-defined controls .

Priority protection prevents lower-priority processes from delaying or interfering with the system that services higher-priority processes. Quotas prevent users or processes from obtaining more than predetermined amounts of resources.

Boundary Protection (sc-7)

Monitor and control communications at the external managed interfaces to the system and at key internal managed interfaces within the system;

Implement subnetworks for publicly accessible system components that are physically,logically separated from internal organizational networks; and

Connect to external networks or systems only through managed interfaces consisting of boundary protection devices arranged in accordance with an organizational security and privacy architecture.

Managed interfaces include gateways, routers, firewalls, guards, network-based malicious code analysis, virtualization systems, or encrypted tunnels implemented within a security architecture. Subnetworks that are physically or logically separated from internal networks are referred to as demilitarized zones or DMZs. Restricting or prohibiting interfaces within organizational systems includes restricting external web traffic to designated web servers within managed interfaces, prohibiting external traffic that appears to be spoofing internal addresses, and prohibiting internal traffic that appears to be spoofing external addresses. [SP 800-189](#f5edfe51-d1f2-422e-9b27-5d0e90b49c72) provides additional information on source address validation techniques to prevent ingress and egress of traffic with spoofed addresses. Commercial telecommunications services are provided by network components and consolidated management systems shared by customers. These services may also include third party-provided access lines and other service elements. Such services may represent sources of increased risk despite contract security provisions. Boundary protection may be implemented as a common control for all or part of an organizational network such that the boundary to be protected is greater than a system-specific boundary (i.e., an authorization boundary).

Transmission Confidentiality and Integrity (sc-8)

Protect the one or more,confidentiality,integrity of transmitted information.

Protecting the confidentiality and integrity of transmitted information applies to internal and external networks as well as any system components that can transmit information, including servers, notebook computers, desktop computers, mobile devices, printers, copiers, scanners, facsimile machines, and radios. Unprotected communication paths are exposed to the possibility of interception and modification. Protecting the confidentiality and integrity of information can be accomplished by physical or logical means. Physical protection can be achieved by using protected distribution systems. A protected distribution system is a wireline or fiber-optics telecommunications system that includes terminals and adequate electromagnetic, acoustical, electrical, and physical controls to permit its use for the unencrypted transmission of classified information. Logical protection can be achieved by employing encryption techniques. Organizations that rely on commercial providers who offer transmission services as commodity services rather than as fully dedicated services may find it difficult to obtain the necessary assurances regarding the implementation of needed controls for transmission confidentiality and integrity. In such situations, organizations determine what types of confidentiality or integrity services are available in standard, commercial telecommunications service packages. If it is not feasible to obtain the necessary controls and assurances of control effectiveness through appropriate contracting vehicles, organizations can implement appropriate compensating controls.

Transmission Confidentiality (sc-9)

Network Disconnect (sc-10)

Terminate the network connection associated with a communications session at the end of the session or after organization-defined time period of inactivity.

Network disconnect applies to internal and external networks. Terminating network connections associated with specific communications sessions includes de-allocating TCP/IP address or port pairs at the operating system level and de-allocating the networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. Periods of inactivity may be established by organizations and include time periods by type of network access or for specific network accesses.

Trusted Path (sc-11)

Provide a physically,logically isolated trusted communications path for communications between the user and the trusted components of the system; and

Permit users to invoke the trusted communications path for communications between the user and the following security functions of the system, including at a minimum, authentication and re-authentication: organization-defined security functions.

Trusted paths are mechanisms by which users can communicate (using input devices such as keyboards) directly with the security functions of systems with the requisite assurance to support security policies. Trusted path mechanisms can only be activated by users or the security functions of organizational systems. User responses that occur via trusted paths are protected from modification by and disclosure to untrusted applications. Organizations employ trusted paths for trustworthy, high-assurance connections between security functions of systems and users, including during system logons. The original implementations of trusted paths employed an out-of-band signal to initiate the path, such as using the key, which does not transmit characters that can be spoofed. In later implementations, a key combination that could not be hijacked was used (e.g., the + + keys). Such key combinations, however, are platform-specific and may not provide a trusted path implementation in every case. The enforcement of trusted communications paths is provided by a specific implementation that meets the reference monitor concept.

Cryptographic Key Establishment and Management (sc-12)

Establish and manage cryptographic keys when cryptography is employed within the system in accordance with the following key management requirements: organization-defined requirements for key generation, distribution, storage, access, and destruction.

Cryptographic key management and establishment can be performed using manual procedures or automated mechanisms with supporting manual procedures. Organizations define key management requirements in accordance with applicable laws, executive orders, directives, regulations, policies, standards, and guidelines and specify appropriate options, parameters, and levels. Organizations manage trust stores to ensure that only approved trust anchors are part of such trust stores. This includes certificates with visibility external to organizational systems and certificates related to the internal operations of systems. [NIST CMVP](#1acdc775-aafb-4d11-9341-dc6a822e9d38) and [NIST CAVP](#84dc1b0c-acb7-4269-84c4-00dbabacd78c) provide additional information on validated cryptographic modules and algorithms that can be used in cryptographic key management and establishment.

Cryptographic Protection (sc-13)

Determine the organization-defined cryptographic uses; and

Implement the following types of cryptography required for each specified cryptographic use: organization-defined types of cryptography for each specified cryptographic use.

Cryptography can be employed to support a variety of security solutions, including the protection of classified information and controlled unclassified information, the provision and implementation of digital signatures, and the enforcement of information separation when authorized individuals have the necessary clearances but lack the necessary formal access approvals. Cryptography can also be used to support random number and hash generation. Generally applicable cryptographic standards include FIPS-validated cryptography and NSA-approved cryptography. For example, organizations that need to protect classified information may specify the use of NSA-approved cryptography. Organizations that need to provision and implement digital signatures may specify the use of FIPS-validated cryptography. Cryptography is implemented in accordance with applicable laws, executive orders, directives, regulations, policies, standards, and guidelines.

Public Access Protections (sc-14)

Collaborative Computing Devices and Applications (sc-15)

Prohibit remote activation of collaborative computing devices and applications with the following exceptions: organization-defined exceptions where remote activation is to be allowed; and

Provide an explicit indication of use to users physically present at the devices.

Collaborative computing devices and applications include remote meeting devices and applications, networked white boards, cameras, and microphones. The explicit indication of use includes signals to users when collaborative computing devices and applications are activated.

Transmission of Security and Privacy Attributes (sc-16)

Associate organization-defined security and privacy attributes with information exchanged between systems and between system components.

Security and privacy attributes can be explicitly or implicitly associated with the information contained in organizational systems or system components. Attributes are abstractions that represent the basic properties or characteristics of an entity with respect to protecting information or the management of personally identifiable information. Attributes are typically associated with internal data structures, including records, buffers, and files within the system. Security and privacy attributes are used to implement access control and information flow control policies; reflect special dissemination, management, or distribution instructions, including permitted uses of personally identifiable information; or support other aspects of the information security and privacy policies. Privacy attributes may be used independently or in conjunction with security attributes.

Public Key Infrastructure Certificates (sc-17)

Issue public key certificates under an organization-defined certificate policy or obtain public key certificates from an approved service provider; and

Include only approved trust anchors in trust stores or certificate stores managed by the organization.

Public key infrastructure (PKI) certificates are certificates with visibility external to organizational systems and certificates related to the internal operations of systems, such as application-specific time services. In cryptographic systems with a hierarchical structure, a trust anchor is an authoritative source (i.e., a certificate authority) for which trust is assumed and not derived. A root certificate for a PKI system is an example of a trust anchor. A trust store or certificate store maintains a list of trusted root certificates.

Mobile Code (sc-18)

Define acceptable and unacceptable mobile code and mobile code technologies; and

Authorize, monitor, and control the use of mobile code within the system.

Mobile code includes any program, application, or content that can be transmitted across a network (e.g., embedded in an email, document, or website) and executed on a remote system. Decisions regarding the use of mobile code within organizational systems are based on the potential for the code to cause damage to the systems if used maliciously. Mobile code technologies include Java applets, JavaScript, HTML5, WebGL, and VBScript. Usage restrictions and implementation guidelines apply to both the selection and use of mobile code installed on servers and mobile code downloaded and executed on individual workstations and devices, including notebook computers and smart phones. Mobile code policy and procedures address specific actions taken to prevent the development, acquisition, and introduction of unacceptable mobile code within organizational systems, including requiring mobile code to be digitally signed by a trusted source.

Voice Over Internet Protocol (sc-19)

Technology-specific; addressed as any other technology or protocol.

Secure Name/address Resolution Service (authoritative Source) (sc-20)

Provide additional data origin authentication and integrity verification artifacts along with the authoritative name resolution data the system returns in response to external name/address resolution queries; and

Provide the means to indicate the security status of child zones and (if the child supports secure resolution services) to enable verification of a chain of trust among parent and child domains, when operating as part of a distributed, hierarchical namespace.

Providing authoritative source information enables external clients, including remote Internet clients, to obtain origin authentication and integrity verification assurances for the host/service name to network address resolution information obtained through the service. Systems that provide name and address resolution services include domain name system (DNS) servers. Additional artifacts include DNS Security Extensions (DNSSEC) digital signatures and cryptographic keys. Authoritative data includes DNS resource records. The means for indicating the security status of child zones include the use of delegation signer resource records in the DNS. Systems that use technologies other than the DNS to map between host and service names and network addresses provide other means to assure the authenticity and integrity of response data.

Secure Name/address Resolution Service (recursive or Caching Resolver) (sc-21)

Request and perform data origin authentication and data integrity verification on the name/address resolution responses the system receives from authoritative sources.

Each client of name resolution services either performs this validation on its own or has authenticated channels to trusted validation providers. Systems that provide name and address resolution services for local clients include recursive resolving or caching domain name system (DNS) servers. DNS client resolvers either perform validation of DNSSEC signatures, or clients use authenticated channels to recursive resolvers that perform such validations. Systems that use technologies other than the DNS to map between host and service names and network addresses provide some other means to enable clients to verify the authenticity and integrity of response data.

Architecture and Provisioning for Name/address Resolution Service (sc-22)

Ensure the systems that collectively provide name/address resolution service for an organization are fault-tolerant and implement internal and external role separation.

Systems that provide name and address resolution services include domain name system (DNS) servers. To eliminate single points of failure in systems and enhance redundancy, organizations employ at least two authoritative domain name system servers?one configured as the primary server and the other configured as the secondary server. Additionally, organizations typically deploy the servers in two geographically separated network subnetworks (i.e., not located in the same physical facility). For role separation, DNS servers with internal roles only process name and address resolution requests from within organizations (i.e., from internal clients). DNS servers with external roles only process name and address resolution information requests from clients external to organizations (i.e., on external networks, including the Internet). Organizations specify clients that can access authoritative DNS servers in certain roles (e.g., by address ranges and explicit lists).

Session Authenticity (sc-23)

Protect the authenticity of communications sessions.

Protecting session authenticity addresses communications protection at the session level, not at the packet level. Such protection establishes grounds for confidence at both ends of communications sessions in the ongoing identities of other parties and the validity of transmitted information. Authenticity protection includes protecting against "man-in-the-middle" attacks, session hijacking, and the insertion of false information into sessions.

Fail in Known State (sc-24)

Fail to a organization-defined known system state for the following failures on the indicated components while preserving organization-defined system state information in failure: list of organization-defined types of system failures on organization-defined system components.

Failure in a known state addresses security concerns in accordance with the mission and business needs of organizations. Failure in a known state prevents the loss of confidentiality, integrity, or availability of information in the event of failures of organizational systems or system components. Failure in a known safe state helps to prevent systems from failing to a state that may cause injury to individuals or destruction to property. Preserving system state information facilitates system restart and return to the operational mode with less disruption of mission and business processes.

Thin Nodes (sc-25)

Employ minimal functionality and information storage on the following system components: organization-defined system components.

The deployment of system components with minimal functionality reduces the need to secure every endpoint and may reduce the exposure of information, systems, and services to attacks. Reduced or minimal functionality includes diskless nodes and thin client technologies.

Decoys (sc-26)

Include components within organizational systems specifically designed to be the target of malicious attacks for detecting, deflecting, and analyzing such attacks.

Decoys (i.e., honeypots, honeynets, or deception nets) are established to attract adversaries and deflect attacks away from the operational systems that support organizational mission and business functions. Use of decoys requires some supporting isolation measures to ensure that any deflected malicious code does not infect organizational systems. Depending on the specific usage of the decoy, consultation with the Office of the General Counsel before deployment may be needed.

Platform-independent Applications (sc-27)

Include within organizational systems the following platform independent applications: organization-defined platform-independent applications.

Platforms are combinations of hardware, firmware, and software components used to execute software applications. Platforms include operating systems, the underlying computer architectures, or both. Platform-independent applications are applications with the capability to execute on multiple platforms. Such applications promote portability and reconstitution on different platforms. Application portability and the ability to reconstitute on different platforms increase the availability of mission-essential functions within organizations in situations where systems with specific operating systems are under attack.

Protection of Information at Rest (sc-28)

Protect the one or more,confidentiality,integrity of the following information at rest: organization-defined information at rest.

Information at rest refers to the state of information when it is not in process or in transit and is located on system components. Such components include internal or external hard disk drives, storage area network devices, or databases. However, the focus of protecting information at rest is not on the type of storage device or frequency of access but rather on the state of the information. Information at rest addresses the confidentiality and integrity of information and covers user information and system information. System-related information that requires protection includes configurations or rule sets for firewalls, intrusion detection and prevention systems, filtering routers, and authentication information. Organizations may employ different mechanisms to achieve confidentiality and integrity protections, including the use of cryptographic mechanisms and file share scanning. Integrity protection can be achieved, for example, by implementing write-once-read-many (WORM) technologies. When adequate protection of information at rest cannot otherwise be achieved, organizations may employ other controls, including frequent scanning to identify malicious code at rest and secure offline storage in lieu of online storage.

Heterogeneity (sc-29)

Employ a diverse set of information technologies for the following system components in the implementation of the system: organization-defined system components.

Increasing the diversity of information technologies within organizational systems reduces the impact of potential exploitations or compromises of specific technologies. Such diversity protects against common mode failures, including those failures induced by supply chain attacks. Diversity in information technologies also reduces the likelihood that the means adversaries use to compromise one system component will be effective against other system components, thus further increasing the adversary work factor to successfully complete planned attacks. An increase in diversity may add complexity and management overhead that could ultimately lead to mistakes and unauthorized configurations.

Concealment and Misdirection (sc-30)

Employ the following concealment and misdirection techniques for organization-defined systems at organization-defined time periods to confuse and mislead adversaries: organization-defined concealment and misdirection techniques.

Concealment and misdirection techniques can significantly reduce the targeting capabilities of adversaries (i.e., window of opportunity and available attack surface) to initiate and complete attacks. For example, virtualization techniques provide organizations with the ability to disguise systems, potentially reducing the likelihood of successful attacks without the cost of having multiple platforms. The increased use of concealment and misdirection techniques and methods?including randomness, uncertainty, and virtualization?may sufficiently confuse and mislead adversaries and subsequently increase the risk of discovery and/or exposing tradecraft. Concealment and misdirection techniques may provide additional time to perform core mission and business functions. The implementation of concealment and misdirection techniques may add to the complexity and management overhead required for the system.

Covert Channel Analysis (sc-31)

Perform a covert channel analysis to identify those aspects of communications within the system that are potential avenues for covert one or more,storage,timing channels; and

Estimate the maximum bandwidth of those channels.

Developers are in the best position to identify potential areas within systems that might lead to covert channels. Covert channel analysis is a meaningful activity when there is the potential for unauthorized information flows across security domains, such as in the case of systems that contain export-controlled information and have connections to external networks (i.e., networks that are not controlled by organizations). Covert channel analysis is also useful for multilevel secure systems, multiple security level systems, and cross-domain systems.

System Partitioning (sc-32)

Partition the system into organization-defined system components residing in separate physical,logical domains or environments based on organization-defined circumstances for physical or logical separation of components.

System partitioning is part of a defense-in-depth protection strategy. Organizations determine the degree of physical separation of system components. Physical separation options include physically distinct components in separate racks in the same room, critical components in separate rooms, and geographical separation of critical components. Security categorization can guide the selection of candidates for domain partitioning. Managed interfaces restrict or prohibit network access and information flow among partitioned system components.

Transmission Preparation Integrity (sc-33)

Non-modifiable Executable Programs (sc-34)

For organization-defined system components, load and execute:

The operating environment from hardware-enforced, read-only media; and

The following applications from hardware-enforced, read-only media: organization-defined applications.

The operating environment for a system contains the code that hosts applications, including operating systems, executives, or virtual machine monitors (i.e., hypervisors). It can also include certain applications that run directly on hardware platforms. Hardware-enforced, read-only media include Compact Disc-Recordable (CD-R) and Digital Versatile Disc-Recordable (DVD-R) disk drives as well as one-time, programmable, read-only memory. The use of non-modifiable storage ensures the integrity of software from the point of creation of the read-only image. The use of reprogrammable, read-only memory can be accepted as read-only media provided that integrity can be adequately protected from the point of initial writing to the insertion of the memory into the system, and there are reliable hardware protections against reprogramming the memory while installed in organizational systems.

External Malicious Code Identification (sc-35)

Include system components that proactively seek to identify network-based malicious code or malicious websites.

External malicious code identification differs from decoys in #sc-26(#sc-26) in that the components actively probe networks, including the Internet, in search of malicious code contained on external websites. Like decoys, the use of external malicious code identification techniques requires some supporting isolation measures to ensure that any malicious code discovered during the search and subsequently executed does not infect organizational systems. Virtualization is a common technique for achieving such isolation.

Distributed Processing and Storage (sc-36)

Distribute the following processing and storage components across multiple physical locations,logical domains: organization-defined processing and storage components.

Distributing processing and storage across multiple physical locations or logical domains provides a degree of redundancy or overlap for organizations. The redundancy and overlap increase the work factor of adversaries to adversely impact organizational operations, assets, and individuals. The use of distributed processing and storage does not assume a single primary processing or storage location. Therefore, it allows for parallel processing and storage.

Out-of-band Channels (sc-37)

Employ the following out-of-band channels for the physical delivery or electronic transmission of organization-defined information, system components, or devices to organization-defined individuals or systems: organization-defined out-of-band channels.

Out-of-band channels include local, non-network accesses to systems; network paths physically separate from network paths used for operational traffic; or non-electronic paths, such as the U.S. Postal Service. The use of out-of-band channels is contrasted with the use of in-band channels (i.e., the same channels) that carry routine operational traffic. Out-of-band channels do not have the same vulnerability or exposure as in-band channels. Therefore, the confidentiality, integrity, or availability compromises of in-band channels will not compromise or adversely affect the out-of-band channels. Organizations may employ out-of-band channels in the delivery or transmission of organizational items, including authenticators and credentials; cryptographic key management information; system and data backups; configuration management changes for hardware, firmware, or software; security updates; maintenance information; and malicious code protection updates.

Operations Security (sc-38)

Employ the following operations security controls to protect key organizational information throughout the system development life cycle: organization-defined operations security controls.

Operations security (OPSEC) is a systematic process by which potential adversaries can be denied information about the capabilities and intentions of organizations by identifying, controlling, and protecting generally unclassified information that specifically relates to the planning and execution of sensitive organizational activities. The OPSEC process involves five steps: identification of critical information, analysis of threats, analysis of vulnerabilities, assessment of risks, and the application of appropriate countermeasures. OPSEC controls are applied to organizational systems and the environments in which those systems operate. OPSEC controls protect the confidentiality of information, including limiting the sharing of information with suppliers, potential suppliers, and other non-organizational elements and individuals. Information critical to organizational mission and business functions includes user identities, element uses, suppliers, supply chain processes, functional requirements, security requirements, system design specifications, testing and evaluation protocols, and security control implementation details.

Process Isolation (sc-39)

Maintain a separate execution domain for each executing system process.

Systems can maintain separate execution domains for each executing process by assigning each process a separate address space. Each system process has a distinct address space so that communication between processes is performed in a manner controlled through the security functions, and one process cannot modify the executing code of another process. Maintaining separate execution domains for executing processes can be achieved, for example, by implementing separate address spaces. Process isolation technologies, including sandboxing or virtualization, logically separate software and firmware from other software, firmware, and data. Process isolation helps limit the access of potentially untrusted software to other system resources. The capability to maintain separate execution domains is available in commercial operating systems that employ multi-state processor technologies.

Wireless Link Protection (sc-40)

Protect external and internal organization-defined wireless links from the following signal parameter attacks: organization-defined types of signal parameter attacks or references to sources for such attacks.

Wireless link protection applies to internal and external wireless communication links that may be visible to individuals who are not authorized system users. Adversaries can exploit the signal parameters of wireless links if such links are not adequately protected. There are many ways to exploit the signal parameters of wireless links to gain intelligence, deny service, or spoof system users. Protection of wireless links reduces the impact of attacks that are unique to wireless systems. If organizations rely on commercial service providers for transmission services as commodity items rather than as fully dedicated services, it may not be possible to implement wireless link protections to the extent necessary to meet organizational security requirements.

Port and I/O Device Access (sc-41)

Physically,Logically disable or remove organization-defined connection ports or input/output devices on the following systems or system components: organization-defined systems or system components.

Connection ports include Universal Serial Bus (USB), Thunderbolt, and Firewire (IEEE 1394). Input/output (I/O) devices include compact disc and digital versatile disc drives. Disabling or removing such connection ports and I/O devices helps prevent the exfiltration of information from systems and the introduction of malicious code from those ports or devices. Physically disabling or removing ports and/or devices is the stronger action.

Sensor Capability and Data (sc-42)

Prohibit one or more,the use of devices possessing organization-defined environmental sensing capabilities in organization-defined facilities, areas, or systems ,the remote activation of environmental sensing capabilities on organizational systems or system components with the following exceptions: organization-defined exceptions where remote activation of sensors is allowed ; and

Provide an explicit indication of sensor use to organization-defined group of users.

Sensor capability and data applies to types of systems or system components characterized as mobile devices, such as cellular telephones, smart phones, and tablets. Mobile devices often include sensors that can collect and record data regarding the environment where the system is in use. Sensors that are embedded within mobile devices include microphones, cameras, Global Positioning System (GPS) mechanisms, and accelerometers. While the sensors on mobiles devices provide an important function, if activated covertly, such devices can potentially provide a means for adversaries to learn valuable information about individuals and organizations. For example, remotely activating the GPS function on a mobile device could provide an adversary with the ability to track the movements of an individual. Organizations may prohibit individuals from bringing cellular telephones or digital cameras into certain designated facilities or controlled areas within facilities where classified information is stored or sensitive conversations are taking place.

Usage Restrictions (sc-43)

Establish usage restrictions and implementation guidelines for the following system components: organization-defined system components; and

Authorize, monitor, and control the use of such components within the system.

Usage restrictions apply to all system components including but not limited to mobile code, mobile devices, wireless access, and wired and wireless peripheral components (e.g., copiers, printers, scanners, optical devices, and other similar technologies). The usage restrictions and implementation guidelines are based on the potential for system components to cause damage to the system and help to ensure that only authorized system use occurs.

Detonation Chambers (sc-44)

Employ a detonation chamber capability within organization-defined system, system component, or location.

Detonation chambers, also known as dynamic execution environments, allow organizations to open email attachments, execute untrusted or suspicious applications, and execute Universal Resource Locator requests in the safety of an isolated environment or a virtualized sandbox. Protected and isolated execution environments provide a means of determining whether the associated attachments or applications contain malicious code. While related to the concept of deception nets, the employment of detonation chambers is not intended to maintain a long-term environment in which adversaries can operate and their actions can be observed. Rather, detonation chambers are intended to quickly identify malicious code and either reduce the likelihood that the code is propagated to user environments of operation or prevent such propagation completely.

System Time Synchronization (sc-45)

Synchronize system clocks within and between systems and system components.

Time synchronization of system clocks is essential for the correct execution of many system services, including identification and authentication processes that involve certificates and time-of-day restrictions as part of access control. Denial of service or failure to deny expired credentials may result without properly synchronized clocks within and between systems and system components. Time is commonly expressed in Coordinated Universal Time (UTC), a modern continuation of Greenwich Mean Time (GMT), or local time with an offset from UTC. The granularity of time measurements refers to the degree of synchronization between system clocks and reference clocks, such as clocks synchronizing within hundreds of milliseconds or tens of milliseconds. Organizations may define different time granularities for system components. Time service can be critical to other security capabilities?such as access control and identification and authentication?depending on the nature of the mechanisms used to support the capabilities.

Cross Domain Policy Enforcement (sc-46)

Implement a policy enforcement mechanism physically,logically between the physical and/or network interfaces for the connecting security domains.

For logical policy enforcement mechanisms, organizations avoid creating a logical path between interfaces to prevent the ability to bypass the policy enforcement mechanism. For physical policy enforcement mechanisms, the robustness of physical isolation afforded by the physical implementation of policy enforcement to preclude the presence of logical covert channels penetrating the security domain may be needed. Contact [ncdsmo@nsa.gov](mailto:ncdsmo@nsa.gov) for more information.

Alternate Communications Paths (sc-47)

Establish organization-defined alternate communications paths for system operations organizational command and control.

An incident, whether adversarial- or nonadversarial-based, can disrupt established communications paths used for system operations and organizational command and control. Alternate communications paths reduce the risk of all communications paths being affected by the same incident. To compound the problem, the inability of organizational officials to obtain timely information about disruptions or to provide timely direction to operational elements after a communications path incident, can impact the ability of the organization to respond to such incidents in a timely manner. Establishing alternate communications paths for command and control purposes, including designating alternative decision makers if primary decision makers are unavailable and establishing the extent and limitations of their actions, can greatly facilitate the organization?s ability to continue to operate and take appropriate actions during an incident.

Sensor Relocation (sc-48)

Relocate organization-defined sensors and monitoring capabilities to organization-defined locations under the following conditions or circumstances: organization-defined conditions or circumstances.

Adversaries may take various paths and use different approaches as they move laterally through an organization (including its systems) to reach their target or as they attempt to exfiltrate information from the organization. The organization often only has a limited set of monitoring and detection capabilities, and they may be focused on the critical or likely infiltration or exfiltration paths. By using communications paths that the organization typically does not monitor, the adversary can increase its chances of achieving its desired goals. By relocating its sensors or monitoring capabilities to new locations, the organization can impede the adversary?s ability to achieve its goals. The relocation of the sensors or monitoring capabilities might be done based on threat information that the organization has acquired or randomly to confuse the adversary and make its lateral transition through the system or organization more challenging.

Hardware-enforced Separation and Policy Enforcement (sc-49)

Implement hardware-enforced separation and policy enforcement mechanisms between organization-defined security domains.

System owners may require additional strength of mechanism and robustness to ensure domain separation and policy enforcement for specific types of threats and environments of operation. Hardware-enforced separation and policy enforcement provide greater strength of mechanism than software-enforced separation and policy enforcement.

Software-enforced Separation and Policy Enforcement (sc-50)

Implement software-enforced separation and policy enforcement mechanisms between organization-defined security domains.

System owners may require additional strength of mechanism to ensure domain separation and policy enforcement for specific types of threats and environments of operation.

Hardware-based Protection (sc-51)

Employ hardware-based, write-protect for organization-defined system firmware components; and

Implement specific procedures for organization-defined authorized individuals to manually disable hardware write-protect for firmware modifications and re-enable the write-protect prior to returning to operational mode.

None.

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