SC – System and Communications Protection

NIST SP 800-53 Rev. 5 – SC – System and Communications Protection

1.Kravtext (engelskt original)#

SC-1 – Policy and Procedures#

• a. Develop, document, and disseminate to [organization-defined personnel or roles]:
  • 1. [organization-level or mission/business-process-level or system-level] system and communications protection policy that:
    • (a) Addresses purpose, scope, roles, responsibilities, management commitment, coordination among organizational entities, and compliance; and
    • (b) Is consistent with applicable laws, executive orders, directives, regulations, policies, standards, and guidelines; and
  • 2. Procedures to facilitate the implementation of the system and communications protection policy and the associated system and communications protection controls;
• b. Designate an [organization-defined official] to manage the development, documentation, and dissemination of the system and communications protection policy and procedures; and
• c. Review and update the current system and communications protection:
  • 1. Policy [organization-defined frequency] and following [organization-defined events] ; and
  • 2. Procedures [organization-defined frequency] and following [organization-defined events].

SC-2 – Separation of System and User Functionality#

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

SC-2(1) – Interfaces for Non-privileged Users

Prevent the presentation of system management functionality at interfaces to non-privileged users.

SC-2(2) – Disassociability

Store state information from applications and software separately.

SC-3 – Security Function Isolation#

Isolate security functions from nonsecurity functions.

SC-3(1) – Hardware Separation

Employ hardware separation mechanisms to implement security function isolation.

SC-3(2) – Access and Flow Control Functions

Isolate security functions enforcing access and information flow control from nonsecurity functions and from other security functions.

SC-3(3) – Minimize Nonsecurity Functionality

Minimize the number of nonsecurity functions included within the isolation boundary containing security functions.

SC-3(4) – Module Coupling and Cohesiveness

Implement security functions as largely independent modules that maximize internal cohesiveness within modules and minimize coupling between modules.

SC-3(5) – Layered Structures

Implement security functions as a layered structure minimizing interactions between layers of the design and avoiding any dependence by lower layers on the functionality or correctness of higher layers.

SC-4 – Information in Shared System Resources#

Prevent unauthorized and unintended information transfer via shared system resources.

SC-4(1) – Security Levels

SC-4(2) – Multilevel or Periods Processing

Prevent unauthorized information transfer via shared resources in accordance with [organization-defined procedures] when system processing explicitly switches between different information classification levels or security categories.

SC-5 – Denial-of-service Protection#

• a. [protect against or limit] the effects of the following types of denial-of-service events: [organization-defined types of denial-of-service events] ; and
• b. Employ the following controls to achieve the denial-of-service objective: [organization-defined controls by type of denial-of-service event].

SC-5(1) – Restrict Ability to Attack Other Systems

Restrict the ability of individuals to launch the following denial-of-service attacks against other systems: [organization-defined denial-of-service attacks].

SC-5(2) – Capacity, Bandwidth, and Redundancy

Manage capacity, bandwidth, or other redundancy to limit the effects of information flooding denial-of-service attacks.

SC-5(3) – Detection and Monitoring

• (a) Employ the following monitoring tools to detect indicators of denial-of-service attacks against, or launched from, the system: [organization-defined monitoring tools] ; and
• (b) Monitor the following system resources to determine if sufficient resources exist to prevent effective denial-of-service attacks: [organization-defined system resources].

SC-6 – Resource Availability#

Protect the availability of resources by allocating [organization-defined resources] by [priority or quota or [organization-defined controls] ].

SC-7 – Boundary Protection#

• a. Monitor and control communications at the external managed interfaces to the system and at key internal managed interfaces within the system;
• b. Implement subnetworks for publicly accessible system components that are [physically or logically] separated from internal organizational networks; and
• c. 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.

SC-7(1) – Physically Separated Subnetworks

SC-7(2) – Public Access

SC-7(3) – Access Points

Limit the number of external network connections to the system.

SC-7(4) – External Telecommunications Services

• (a) Implement a managed interface for each external telecommunication service;
• (b) Establish a traffic flow policy for each managed interface;
• (c) Protect the confidentiality and integrity of the information being transmitted across each interface;
• (d) Document each exception to the traffic flow policy with a supporting mission or business need and duration of that need;
• (e) Review exceptions to the traffic flow policy [organization-defined frequency] and remove exceptions that are no longer supported by an explicit mission or business need;
• (f) Prevent unauthorized exchange of control plane traffic with external networks;
• (g) Publish information to enable remote networks to detect unauthorized control plane traffic from internal networks; and
• (h) Filter unauthorized control plane traffic from external networks.

SC-7(5) – Deny by Default — Allow by Exception

Deny network communications traffic by default and allow network communications traffic by exception [at managed interfaces or for [organization-defined systems] ].

SC-7(6) – Response to Recognized Failures

SC-7(7) – Split Tunneling for Remote Devices

Prevent split tunneling for remote devices connecting to organizational systems unless the split tunnel is securely provisioned using [organization-defined safeguards].

SC-7(8) – Route Traffic to Authenticated Proxy Servers

Route [organization-defined internal communications traffic] to [organization-defined external networks] through authenticated proxy servers at managed interfaces.

SC-7(9) – Restrict Threatening Outgoing Communications Traffic

• (a) Detect and deny outgoing communications traffic posing a threat to external systems; and
• (b) Audit the identity of internal users associated with denied communications.

SC-7(10) – Prevent Exfiltration

• (a) Prevent the exfiltration of information; and
• (b) Conduct exfiltration tests [organization-defined frequency].

SC-7(11) – Restrict Incoming Communications Traffic

Only allow incoming communications from [organization-defined authorized sources] to be routed to [organization-defined authorized destinations].

SC-7(12) – Host-based Protection

Implement [organization-defined host-based boundary protection mechanisms] at [organization-defined system components].

SC-7(13) – Isolation of Security Tools, Mechanisms, and Support Components

Isolate [organization-defined information security tools, mechanisms, and support components] from other internal system components by implementing physically separate subnetworks with managed interfaces to other components of the system.

SC-7(14) – Protect Against Unauthorized Physical Connections

Protect against unauthorized physical connections at [organization-defined managed interfaces].

SC-7(15) – Networked Privileged Accesses

Route networked, privileged accesses through a dedicated, managed interface for purposes of access control and auditing.

SC-7(16) – Prevent Discovery of System Components

Prevent the discovery of specific system components that represent a managed interface.

SC-7(17) – Automated Enforcement of Protocol Formats

Enforce adherence to protocol formats.

SC-7(18) – Fail Secure

Prevent systems from entering unsecure states in the event of an operational failure of a boundary protection device.

SC-7(19) – Block Communication from Non-organizationally Configured Hosts

Block inbound and outbound communications traffic between [organization-defined communication clients] that are independently configured by end users and external service providers.

SC-7(20) – Dynamic Isolation and Segregation

Provide the capability to dynamically isolate [organization-defined system components] from other system components.

SC-7(21) – Isolation of System Components

Employ boundary protection mechanisms to isolate [organization-defined system components] supporting [organization-defined missions and/or business functions].

SC-7(22) – Separate Subnets for Connecting to Different Security Domains

Implement separate network addresses to connect to systems in different security domains.

SC-7(23) – Disable Sender Feedback on Protocol Validation Failure

Disable feedback to senders on protocol format validation failure.

SC-7(24) – Personally Identifiable Information

For systems that process personally identifiable information:

• (a) Apply the following processing rules to data elements of personally identifiable information: [organization-defined processing rules];
• (b) Monitor for permitted processing at the external interfaces to the system and at key internal boundaries within the system;
• (c) Document each processing exception; and
• (d) Review and remove exceptions that are no longer supported.

SC-7(25) – Unclassified National Security System Connections

Prohibit the direct connection of [organization-defined unclassified national security system] to an external network without the use of [organization-defined boundary protection device].

SC-7(26) – Classified National Security System Connections

Prohibit the direct connection of a classified national security system to an external network without the use of [organization-defined boundary protection device].

SC-7(27) – Unclassified Non-national Security System Connections

Prohibit the direct connection of [organization-defined unclassified, non-national security system] to an external network without the use of [organization-defined boundary protection device].

SC-7(28) – Connections to Public Networks

Prohibit the direct connection of [organization-defined system] to a public network.

SC-7(29) – Separate Subnets to Isolate Functions

Implement [physically or logically] separate subnetworks to isolate the following critical system components and functions: [organization-defined critical system components and functions].

SC-8 – Transmission Confidentiality and Integrity#

Protect the [confidentiality or integrity] of transmitted information.

SC-8(1) – Cryptographic Protection

Implement cryptographic mechanisms to [prevent unauthorized disclosure of information or detect changes to information] during transmission.

SC-8(2) – Pre- and Post-transmission Handling

Maintain the [confidentiality or integrity] of information during preparation for transmission and during reception.

SC-8(3) – Cryptographic Protection for Message Externals

Implement cryptographic mechanisms to protect message externals unless otherwise protected by [organization-defined alternative physical controls].

SC-8(4) – Conceal or Randomize Communications

Implement cryptographic mechanisms to conceal or randomize communication patterns unless otherwise protected by [organization-defined alternative physical controls].

SC-8(5) – Protected Distribution System

Implement [organization-defined protected distribution system] to [prevent unauthorized disclosure of information or detect changes to information] during transmission.

SC-9 – Transmission Confidentiality#

SC-10 – Network Disconnect#

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

SC-11 – Trusted Path#

• a. Provide a [physically or logically] isolated trusted communications path for communications between the user and the trusted components of the system; and
• b. 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].

SC-11(1) – Irrefutable Communications Path

• (a) Provide a trusted communications path that is irrefutably distinguishable from other communications paths; and
• (b) Initiate the trusted communications path for communications between the [organization-defined security functions] of the system and the user.

SC-12 – Cryptographic Key Establishment and Management#

Establish and manage cryptographic keys when cryptography is employed within the system in accordance with the following key management requirements: [organization-defined requirements].

SC-12(1) – Availability

Maintain availability of information in the event of the loss of cryptographic keys by users.

SC-12(2) – Symmetric Keys

Produce, control, and distribute symmetric cryptographic keys using [NIST FIPS-validated or NSA-approved] key management technology and processes.

SC-12(3) – Asymmetric Keys

Produce, control, and distribute asymmetric cryptographic keys using [NSA-approved key management technology and processes or prepositioned keying material or DoD-approved or DoD-issued Medium Assurance PKI certificates or DoD-approved or DoD-issued Medium Hardware Assurance PKI certificates and hardware security tokens that protect the user’s private key or certificates issued in accordance with organization-defined requirements].

SC-12(4) – PKI Certificates

SC-12(5) – PKI Certificates / Hardware Tokens

SC-12(6) – Physical Control of Keys

Maintain physical control of cryptographic keys when stored information is encrypted by external service providers.

SC-13 – Cryptographic Protection#

• a. Determine the [organization-defined cryptographic uses] ; and
• b. Implement the following types of cryptography required for each specified cryptographic use: [organization-defined types of cryptography].

SC-13(1) – FIPS-validated Cryptography

SC-13(2) – NSA-approved Cryptography

SC-13(3) – Individuals Without Formal Access Approvals

SC-13(4) – Digital Signatures

SC-14 – Public Access Protections#

SC-15 – Collaborative Computing Devices and Applications#

• a. Prohibit remote activation of collaborative computing devices and applications with the following exceptions: [organization-defined exceptions where remote activation is to be allowed] ; and
• b. Provide an explicit indication of use to users physically present at the devices.

SC-15(1) – Physical or Logical Disconnect

Provide [physical or logical] disconnect of collaborative computing devices in a manner that supports ease of use.

SC-15(2) – Blocking Inbound and Outbound Communications Traffic

SC-15(3) – Disabling and Removal in Secure Work Areas

Disable or remove collaborative computing devices and applications from [organization-defined systems or system components] in [organization-defined secure work areas].

SC-15(4) – Explicitly Indicate Current Participants

Provide an explicit indication of current participants in [organization-defined online meetings and teleconferences].

SC-16 – Transmission of Security and Privacy Attributes#

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

SC-16(1) – Integrity Verification

Verify the integrity of transmitted security and privacy attributes.

SC-16(2) – Anti-spoofing Mechanisms

Implement anti-spoofing mechanisms to prevent adversaries from falsifying the security attributes indicating the successful application of the security process.

SC-16(3) – Cryptographic Binding

Implement [organization-defined mechanisms or techniques] to bind security and privacy attributes to transmitted information.

SC-17 – Public Key Infrastructure Certificates#

• a. Issue public key certificates under an [organization-defined certificate policy] or obtain public key certificates from an approved service provider; and
• b. Include only approved trust anchors in trust stores or certificate stores managed by the organization.

SC-18 – Mobile Code#

• a. Define acceptable and unacceptable mobile code and mobile code technologies; and
• b. Authorize, monitor, and control the use of mobile code within the system.

SC-18(1) – Identify Unacceptable Code and Take Corrective Actions

Identify [organization-defined unacceptable mobile code] and take [organization-defined corrective actions].

SC-18(2) – Acquisition, Development, and Use

Verify that the acquisition, development, and use of mobile code to be deployed in the system meets [organization-defined mobile code requirements].

SC-18(3) – Prevent Downloading and Execution

Prevent the download and execution of [organization-defined unacceptable mobile code].

SC-18(4) – Prevent Automatic Execution

Prevent the automatic execution of mobile code in [organization-defined software applications] and enforce [organization-defined actions] prior to executing the code.

SC-18(5) – Allow Execution Only in Confined Environments

Allow execution of permitted mobile code only in confined virtual machine environments.

SC-19 – Voice Over Internet Protocol#

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

SC-20 – Secure Name/Address Resolution Service (Authoritative Source)#

• a. 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
• b. 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.

SC-20(1) – Child Subspaces

SC-20(2) – Data Origin and Integrity

Provide data origin and integrity protection artifacts for internal name/address resolution queries.

SC-21 – Secure Name/Address Resolution Service (Recursive or Caching Resolver)#

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

SC-21(1) – Data Origin and Integrity

SC-22 – Architecture and Provisioning for Name/Address Resolution Service#

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

SC-23 – Session Authenticity#

Protect the authenticity of communications sessions.

SC-23(1) – Invalidate Session Identifiers at Logout

Invalidate session identifiers upon user logout or other session termination.

SC-23(2) – User-initiated Logouts and Message Displays

SC-23(3) – Unique System-generated Session Identifiers

Generate a unique session identifier for each session with [organization-defined randomness requirements] and recognize only session identifiers that are system-generated.

SC-23(4) – Unique Session Identifiers with Randomization

SC-23(5) – Allowed Certificate Authorities

Only allow the use of [organization-defined certificated authorities] for verification of the establishment of protected sessions.

SC-24 – Fail in Known State#

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: [organization-defined types of system failures on system components].

SC-25 – Thin Nodes#

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

SC-26 – Decoys#

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

SC-26(1) – Detection of Malicious Code

SC-27 – Platform-independent Applications#

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

SC-28 – Protection of Information at Rest#

Protect the [confidentiality or integrity] of the following information at rest: [organization-defined information at rest].

SC-28(1) – Cryptographic Protection

Implement cryptographic mechanisms to prevent unauthorized disclosure and modification of the following information at rest on [organization-defined system components or media]: [organization-defined information].

SC-28(2) – Offline Storage

Remove the following information from online storage and store offline in a secure location: [organization-defined information].

SC-28(3) – Cryptographic Keys

Provide protected storage for cryptographic keys [[organization-defined safeguards] or hardware-protected key store].

SC-29 – Heterogeneity#

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

SC-29(1) – Virtualization Techniques

Employ virtualization techniques to support the deployment of a diversity of operating systems and applications that are changed [organization-defined frequency].

SC-30 – Concealment and Misdirection#

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].

SC-30(1) – Virtualization Techniques

SC-30(2) – Randomness

Employ [organization-defined techniques] to introduce randomness into organizational operations and assets.

SC-30(3) – Change Processing and Storage Locations

Change the location of [organization-defined processing and/or storage][organization-defined time frequency] or random time intervals]].

SC-30(4) – Misleading Information

Employ realistic, but misleading information in [organization-defined system components] about its security state or posture.

SC-30(5) – Concealment of System Components

Employ the following techniques to hide or conceal [organization-defined system components]: [organization-defined techniques].

SC-31 – Covert Channel Analysis#

• a. Perform a covert channel analysis to identify those aspects of communications within the system that are potential avenues for covert [storage or timing] channels; and
• b. Estimate the maximum bandwidth of those channels.

SC-31(1) – Test Covert Channels for Exploitability

Test a subset of the identified covert channels to determine the channels that are exploitable.

SC-31(2) – Maximum Bandwidth

Reduce the maximum bandwidth for identified covert [storage or timing] channels to [organization-defined values].

SC-31(3) – Measure Bandwidth in Operational Environments

Measure the bandwidth of [organization-defined subset of identified covert channels] in the operational environment of the system.

SC-32 – System Partitioning#

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

SC-32(1) – Separate Physical Domains for Privileged Functions

Partition privileged functions into separate physical domains.

SC-33 – Transmission Preparation Integrity#

SC-34 – Non-modifiable Executable Programs#

For [organization-defined system components] , load and execute:

• a. The operating environment from hardware-enforced, read-only media; and
• b. The following applications from hardware-enforced, read-only media: [organization-defined applications].

SC-34(1) – No Writable Storage

Employ [organization-defined system components] with no writeable storage that is persistent across component restart or power on/off.

SC-34(2) – Integrity Protection on Read-only Media

Protect the integrity of information prior to storage on read-only media and control the media after such information has been recorded onto the media.

SC-34(3) – Hardware-based Protection

SC-35 – External Malicious Code Identification#

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

SC-36 – Distributed Processing and Storage#

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

SC-36(1) – Polling Techniques

• (a) Employ polling techniques to identify potential faults, errors, or compromises to the following processing and storage components: [organization-defined distributed processing and storage components] ; and
• (b) Take the following actions in response to identified faults, errors, or compromises: [organization-defined actions].

SC-36(2) – Synchronization

Synchronize the following duplicate systems or system components: [organization-defined duplicate systems or system components].

SC-37 – Out-of-band Channels#

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].

SC-37(1) – Ensure Delivery and Transmission

Employ [organization-defined controls] to ensure that only [organization-defined individuals or systems] receive the following information, system components, or devices: [organization-defined information, system components, or devices].

SC-38 – Operations Security#

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

SC-39 – Process Isolation#

Maintain a separate execution domain for each executing system process.

SC-39(1) – Hardware Separation

Implement hardware separation mechanisms to facilitate process isolation.

SC-39(2) – Separate Execution Domain Per Thread

Maintain a separate execution domain for each thread in [organization-defined multi-threaded processing].

SC-40 – Wireless Link Protection#

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].

SC-40(1) – Electromagnetic Interference

Implement cryptographic mechanisms that achieve [organization-defined level of protection] against the effects of intentional electromagnetic interference.

SC-40(2) – Reduce Detection Potential

Implement cryptographic mechanisms to reduce the detection potential of wireless links to [organization-defined level of reduction].

SC-40(3) – Imitative or Manipulative Communications Deception

Implement cryptographic mechanisms to identify and reject wireless transmissions that are deliberate attempts to achieve imitative or manipulative communications deception based on signal parameters.

SC-40(4) – Signal Parameter Identification

Implement cryptographic mechanisms to prevent the identification of [organization-defined wireless transmitters] by using the transmitter signal parameters.

SC-41 – Port and I/O Device Access#

[physically or 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].

SC-42 – Sensor Capability and Data#

• a. Prohibit [the use of devices possessing [organization-defined environmental sensing capabilities] in [organization-defined facilities, areas, or systems] or 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
• b. Provide an explicit indication of sensor use to [organization-defined group of users].

SC-42(1) – Reporting to Authorized Individuals or Roles

Verify that the system is configured so that data or information collected by the [organization-defined sensors] is only reported to authorized individuals or roles.

SC-42(2) – Authorized Use

Employ the following measures so that data or information collected by [organization-defined value] is only used for authorized purposes: [organization-defined measures].

SC-42(3) – Prohibit Use of Devices

SC-42(4) – Notice of Collection

Employ the following measures to facilitate an individual’s awareness that personally identifiable information is being collected by [organization-defined sensors]: [organization-defined measures].

SC-42(5) – Collection Minimization

Employ [organization-defined sensors] that are configured to minimize the collection of information about individuals that is not needed.

SC-43 – Usage Restrictions#

• a. Establish usage restrictions and implementation guidelines for the following system components: [organization-defined components] ; and
• b. Authorize, monitor, and control the use of such components within the system.

SC-44 – Detonation Chambers#

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

SC-45 – System Time Synchronization#

Synchronize system clocks within and between systems and system components.

SC-45(1) – Synchronization with Authoritative Time Source

• (a) Compare the internal system clocks [organization-defined frequency] with [organization-defined authoritative time source] ; and
• (b) Synchronize the internal system clocks to the authoritative time source when the time difference is greater than [organization-defined time period].

SC-45(2) – Secondary Authoritative Time Source

• (a) Identify a secondary authoritative time source that is in a different geographic region than the primary authoritative time source; and
• (b) Synchronize the internal system clocks to the secondary authoritative time source if the primary authoritative time source is unavailable.

SC-46 – Cross Domain Policy Enforcement#

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

SC-47 – Alternate Communications Paths#

Establish [organization-defined alternate communication paths] for system operations organizational command and control.

SC-48 – Sensor Relocation#

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

SC-48(1) – Dynamic Relocation of Sensors or Monitoring Capabilities

Dynamically relocate [organization-defined sensors and monitoring capabilities] to [organization-defined locations] under the following conditions or circumstances: [organization-defined conditions or circumstances].

SC-49 – Hardware-enforced Separation and Policy Enforcement#

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

SC-50 – Software-enforced Separation and Policy Enforcement#

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

SC-51 – Hardware-based Protection#

• a. Employ hardware-based, write-protect for [organization-defined system firmware components] ; and
• b. 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.

National Institute of Standards and Technology, OSCAL release 5.2.0. Republished courtesy of the National Institute of Standards and Technology. CC0 1.0. Source.