# System and Communications Protection Policy

**Template version:** 1.0.0 · **Baseline:** Moderate · **Edition:** Annotated (with guidance) · **NIST basis:** SP 800-53 Rev. 5, release 5.2.0

*Tailor this template before adoption; it is not legal advice.* Latest version: <https://kston83.github.io/nist-guide/templates/policies/sc/>. Dedicated to the public domain under CC0 1.0 (<https://creativecommons.org/publicdomain/zero/1.0/>): adopt and change it without attribution.

> **Guidance:** The sections before and after Policy statements meet SC-1, which asks for a policy that addresses purpose, scope, roles, responsibilities, management commitment, coordination and compliance, plus procedures, dissemination, a designated official and a review cycle. Assessors check each element, so keep every section even when it is short. Each statement cites the SC-1 item it meets. If you adopt several family policies, the same sections repeat in each; that is expected, and it lets each policy stand alone.

## Purpose

This policy states what [Organization name] requires for System and Communications Protection, and who is accountable for meeting those requirements. (SC-1a.1(a))

## Scope

This policy applies at the [Select one or more: organization-level; mission/business-process-level; system-level. Typical: organization-level] to every system that [Organization name] owns or operates, or that is operated on its behalf, and to every person with access to those systems, including employees, contractors and partners. (SC-1a.1(a))

## Roles and responsibilities

- The [Chief Information Security Officer] is accountable for this policy and shall approve exceptions to it. (SC-1a.1(a))
- The [Fill in: an official to manage the system and communications protection policy and procedures. Typical: Chief Information Security Officer] shall manage the development, documentation and dissemination of this policy and its procedures. (SC-1b)
- Each [System owner] shall implement this policy for their system and document how in the system security plan. (SC-1a.1(a))
- Each person within scope shall follow this policy and report suspected violations to the [Chief Information Security Officer]. (SC-1a.1(a))

## Management commitment

The [Senior leader] approves this policy and shall provide the resources needed to implement it. (SC-1a.1(a))

## Coordination

The [Chief Information Security Officer] shall coordinate this policy with the legal, privacy, human resources and procurement functions, and with the owners of related policies, before each approval. (SC-1a.1(a))

## Compliance

- This policy shall be consistent with the laws, executive orders, directives, regulations, policies, standards and guidelines that apply to [Organization name], including [Fill in: laws, regulations and standards that apply to the organization]. (SC-1a.1(b))
- The [Chief Information Security Officer] shall review compliance with this policy through the organization's assessment and continuous monitoring activities. (SC-1a.1(a))
- An exception to this policy shall be requested in writing, approved by the [Chief Information Security Officer], time-limited and recorded with its compensating measures. (SC-1a.1(a))
- Violations of this policy shall be handled through the organization's sanctions process. (SC-1a.1(a))

## Procedures

The [Fill in: an official to manage the system and communications protection policy and procedures. Typical: Chief Information Security Officer] shall ensure that documented procedures exist to implement this policy and its associated controls. (SC-1a.2)

## Dissemination

- The [Fill in: an official to manage the system and communications protection policy and procedures. Typical: Chief Information Security Officer] shall disseminate this policy to [Fill in: personnel or roles to whom the system and communications protection policy is to be disseminated. Typical: everyone within its scope, through the policy library]. (SC-1a)
- The [Fill in: an official to manage the system and communications protection policy and procedures. Typical: Chief Information Security Officer] shall disseminate the procedures that implement this policy to [Fill in: personnel or roles to whom the system and communications protection procedures are to be disseminated. Typical: the people who carry them out, and the system owners]. (SC-1a)

## Policy statements

> **Guidance:** Each statement below comes from the clause for one control or enhancement in the chosen baseline. The reference at the end of each statement names the control item it meets.

### Separation of system and user functionality (SC-2)

> **Guidance:** Keep administration interfaces apart from the interfaces users see: separate administrative consoles, ports or network segments, separate administrator accounts, and management planes not reachable from user networks or the internet.

- The [System owner] shall ensure the system separates user functionality, including user interface services, from system management functionality. (SC-2)

### Information in shared system resources (SC-4)

> **Guidance:** This control is about residual information: memory, storage and caches reused by another user or process must not reveal what the last one left. Operating systems and cloud platforms usually provide it; the system owner confirms it and covers any shared resources the application manages itself.

- The [System owner] shall ensure the system prevents unauthorized and unintended information transfer through shared system resources. (SC-4)

### Denial-of-service protection (SC-5)

> **Guidance:** Most organizations meet this through their internet or cloud provider's denial-of-service protection, plus rate limiting and autoscaling for their own services. Record which protections are inherited and which the system provides.

- The [System owner] shall ensure the system can [Select one: protect against; limit. Typical: protect against] the effects of the following types of denial-of-service events: [Fill in: types of denial-of-service events to be protected against or limited. Typical: network floods, protocol attacks and application-layer floods against internet-facing services]. (SC-5a)
- The [System owner] shall employ the following controls to achieve the denial-of-service objective: [Fill in: controls to achieve the denial-of-service objective by type of denial-of-service event. Typical: an upstream or cloud denial-of-service protection service for internet-facing services, rate limiting at load balancers and application gateways, and capacity that scales automatically]. (SC-5b)

### Boundary protection (SC-7)

> **Guidance:** Every external connection goes through a managed interface, such as a firewall, cloud security group, gateway or proxy, and public-facing components sit in their own subnetwork. The boundary diagram in the system security plan is where assessors start. The [Boundary Protection Standard](https://kston83.github.io/nist-guide/templates/standards/boundary-protection-standard/) sets the managed interfaces, rule sets, allowed flows and review cycle.

- The [System owner] shall monitor and control communications at the external managed interfaces to the system and at key internal managed interfaces within the system. (SC-7a)
- The [System owner] shall implement subnetworks for publicly accessible system components that are [Select one: physically; logically. Typical: logically] separated from internal organizational networks. (SC-7b)
- The [System owner] shall connect the system to external networks or systems only through managed interfaces consisting of boundary protection devices arranged in accordance with the organization's security and privacy architecture. (SC-7c)

#### Federal systems

Federal civilian agencies secure their network connections under CISA's [Trusted Internet Connections (TIC) 3.0](https://www.cisa.gov/resources-tools/programs/trusted-internet-connections-tic) program, which implements OMB M-19-26, Update to the Trusted Internet Connections (TIC) Initiative (September 12, 2019). TIC 3.0 is set out in CISA's core guidance documents and use cases (as of September 2026).

- The [System owner] shall implement the system's external connections in accordance with the agency's TIC 3.0 architecture and the TIC 3.0 use cases that apply to the system. (SC-7c)

### Access points (SC-7(3))

- The [System owner] shall limit the number of external network connections to the system. (SC-7(3))

### External telecommunications services (SC-7(4))

> **Guidance:** Control plane traffic is the routing and signaling traffic between networks, such as BGP route announcements. Items (f) to (h) usually fall to the network or internet service team: route filtering, and publishing the organization's address space and routing policy so others can detect hijacked routes.

- The [System owner] shall implement a managed interface for each external telecommunication service. (SC-7(4)(a))
- The [System owner] shall establish a traffic flow policy for each managed interface. (SC-7(4)(b))
- The [System owner] shall protect the confidentiality and integrity of the information transmitted across each interface. (SC-7(4)(c))
- The [System owner] shall document each exception to the traffic flow policy with the mission or business need that supports it and the duration of that need. (SC-7(4)(d))
- The [System owner] shall review exceptions to the traffic flow policy [Fill in: the frequency at which to review exceptions to traffic flow policy. Typical: at least annually, and when the system changes], and remove exceptions that an explicit mission or business need no longer supports. (SC-7(4)(e))
- The [System owner] shall prevent unauthorized exchange of control plane traffic with external networks. (SC-7(4)(f))
- The [System owner] shall publish information that enables remote networks to detect unauthorized control plane traffic from internal networks. (SC-7(4)(g))
- The [System owner] shall filter unauthorized control plane traffic from external networks. (SC-7(4)(h))

### Deny by default, allow by exception (SC-7(5))

- The [System owner] shall ensure network communications traffic is denied by default and allowed by exception [Select one or more: at managed interfaces; for [Assignment: organization-defined systems]. Typical: at managed interfaces]. (SC-7(5))

### Split tunneling for remote devices (SC-7(7))

> **Guidance:** Split tunneling lets a remote device reach the internet directly while connected to the organization's network, bypassing its boundary protections. Where a zero trust access service replaces the virtual private network, record how its design meets the intent.

- The [System owner] shall prevent split tunneling for remote devices connecting to organizational systems, except where the split tunnel is securely provisioned using these safeguards: [Fill in: safeguards to securely provision split tunneling. Typical: none; split tunneling is disabled for organization-managed remote devices]. (SC-7(7))

### Route traffic to authenticated proxy servers (SC-7(8))

- The [System owner] shall route [Fill in: internal communications traffic to be routed to external networks. Typical: outbound web traffic from internal users] to [Fill in: external networks to which internal communications traffic is to be routed. Typical: the internet] through authenticated proxy servers at managed interfaces. (SC-7(8))

### Transmission confidentiality and integrity (SC-8)

> **Guidance:** Protect information while it moves, inside the system as well as across its boundary. At Moderate and High, SC-8(1) makes that protection cryptographic, using the cryptography SC-13 requires.

- The [System owner] shall ensure the system protects the [Select one or more: confidentiality; integrity. Typical: confidentiality and integrity] of transmitted information. (SC-8)

#### Federal systems

CISA [Binding Operational Directive 18-01](https://www.cisa.gov/news-events/directives/bod-18-01-enhance-email-and-web-security), Enhance Email and Web Security (October 16, 2017), requires that "All publicly accessible Federal websites and web services provide service through a secure connection (HTTPS-only, with HSTS)", that internet-facing mail servers offer STARTTLS, and that SSLv2, SSLv3, 3DES and RC4 are disabled on mail servers. CISA's directive page does not mark it revoked (as of September 2026).

- The [System owner] shall ensure each publicly accessible website and web service of the system provides service only through HTTPS, with HTTP Strict Transport Security. (SC-8)
- The [System owner] shall ensure each internet-facing mail server of the system offers STARTTLS. (SC-8)
- The [System owner] shall ensure SSLv2, SSLv3 and the 3DES and RC4 ciphers are disabled on the system's mail servers. (SC-8)

### Cryptographic protection (SC-8(1))

> **Guidance:** In practice: TLS 1.2 or later for web, API and database connections, SSH for administration, IPsec or TLS for virtual private networks, and encryption on internal service-to-service traffic. Cleartext protocols such as Telnet and unencrypted FTP are disabled.

- The [System owner] shall implement cryptographic mechanisms to [Select one or more: prevent unauthorized disclosure of information; detect changes to information. Typical: prevent unauthorized disclosure of information and detect changes to information] during transmission. (SC-8(1))

### Network disconnect (SC-10)

> **Guidance:** SC-10 ends the network connection; AC-12 ends the user's session. Keep the two times consistent: the typical value here matches the 30 minutes AC-12 sets for remote and web sessions.

- The [System owner] shall ensure the system terminates the network connection associated with a communications session at the end of the session or after [Fill in: a time period of inactivity after which the system terminates a network connection associated with a communication session. Typical: 30 minutes] of inactivity. (SC-10)

### Cryptographic key establishment and management (SC-12)

> **Guidance:** Key management is where encryption usually fails: keys stored with the data, or usable by every administrator. NIST SP 800-57 Part 1 is the usual reference for key management requirements. Cloud key management services and hardware security modules handle most of it; the system owner decides who can use and administer each key. The [Encryption and Key Management Standard](https://kston83.github.io/nist-guide/templates/standards/encryption-and-key-management-standard/) sets the key generation, storage, access, replacement and destruction requirements this clause refers to.

- The [System owner] shall establish and manage cryptographic keys, wherever the system employs cryptography, in accordance with [Fill in: requirements for key generation, distribution, storage, access, and destruction. Typical: the requirements for key generation, distribution, storage, access and destruction in the encryption and key management standard]. (SC-12)

### Cryptographic protection (SC-13)

> **Guidance:** SC-13 does not require cryptography by itself; SC-8, SC-28, IA-5 and AC-17 do. It sets the standard that cryptography must meet wherever those controls call for it. The cryptographic uses match those under configuration management in CM-3(6). The [Encryption and Key Management Standard](https://kston83.github.io/nist-guide/templates/standards/encryption-and-key-management-standard/) lists the approved algorithms, protocols and modules for each use.

- The [Chief Information Security Officer] shall determine the cryptographic uses for the organization's systems, which include [Fill in: cryptographic uses. Typical: encryption in transit and at rest, digital signatures and authentication]. (SC-13a)
- The [System owner] shall implement the following types of cryptography for each cryptographic use: [Fill in: types of cryptography for each specified cryptographic use. Typical: NIST-approved algorithms in cryptographic modules validated under FIPS 140-3 (or FIPS 140-2 for existing systems)]. (SC-13b)

#### Federal systems

[FIPS 140-3](https://csrc.nist.gov/pubs/fips/140-3/final) (March 22, 2019) "is applicable to all Federal agencies that use cryptography-based security systems to protect sensitive information", and modules validated under NIST's Cryptographic Module Validation Program (CMVP) are considered to conform to it (sections 6 and 9). The CMVP's [FIPS 140-3 transition page](https://csrc.nist.gov/projects/fips-140-3-transition-effort) sets the schedule for moving FIPS 140-2 validations to the Historical List in September 2026; modules on the Historical List remain supported for existing systems, but the standard notes that the Historical List "should not be used for procurement decisions" (as of September 2026).

- The [System owner] shall use cryptographic modules validated by the CMVP wherever the system uses cryptography to protect sensitive information. (SC-13b)
- The [System owner] shall select FIPS 140-3 validated modules for new systems and new purchases. (SC-13b)

### Collaborative computing devices and applications (SC-15)

> **Guidance:** Collaborative computing devices include cameras, microphones, networked whiteboards and conferencing applications. The point is that nobody can switch on a camera or microphone remotely without the people in the room knowing.

- The [System owner] shall prohibit remote activation of collaborative computing devices and applications, with these exceptions: [Fill in: exceptions where remote activation is to be allowed. Typical: none, except conference room equipment that support staff activate for maintenance with the room owner's approval]. (SC-15a)
- The [System owner] shall ensure collaborative computing devices and applications give an explicit indication of use to users physically present at the devices. (SC-15b)

### Public key infrastructure certificates (SC-17)

> **Guidance:** Most organizations obtain certificates for public services from a public certificate authority, which counts as an approved service provider, and run an internal certificate authority under their own certificate policy for internal services. Trust stores should hold only the trust anchors the organization approves.

- The [Chief Information Security Officer] shall ensure public key certificates are issued under [Fill in: a certificate policy for issuing public key certificates. Typical: the organization's certificate policy], or obtained from an approved service provider. (SC-17a)
- The [System owner] shall include only approved trust anchors in trust stores or certificate stores the organization manages. (SC-17b)

### Mobile code (SC-18)

> **Guidance:** Mobile code is software sent from a remote system and run on a local one, such as JavaScript, macros in office documents and browser plug-ins. Define what is acceptable by technology, for example signed macros only and no browser plug-ins, and enforce it through browser and office application settings.

- The [Chief Information Security Officer] shall define acceptable and unacceptable mobile code and mobile code technologies. (SC-18a)
- The [System owner] shall authorize, monitor and control the use of mobile code within the system. (SC-18b)

### Secure name and address resolution service (authoritative source) (SC-20)

> **Guidance:** In practice this is DNSSEC signing for the zones the organization publishes, often a setting at the managed DNS provider. [NIST SP 800-81 Rev. 3](https://csrc.nist.gov/pubs/sp/800/81/r3/final), Secure Domain Name System (DNS) Deployment Guide (March 2026), is the NIST guide to deploying DNS securely, including DNSSEC.

- The [System owner] shall ensure the system provides additional data origin authentication and integrity verification artifacts along with the authoritative name resolution data it returns in response to external name and address resolution queries. (SC-20a)
- When the system operates as part of a distributed, hierarchical namespace, the [System owner] shall ensure it provides the means to indicate the security status of child zones and, if a child supports secure resolution services, to enable verification of a chain of trust among parent and child domains. (SC-20b)

### Secure name and address resolution service (recursive or caching resolver) (SC-21)

> **Guidance:** In practice this is DNSSEC validation turned on at the resolvers the system uses, or a DNS service that validates.

- The [System owner] shall ensure the system requests and performs data origin authentication and data integrity verification on the name and address resolution responses it receives from authoritative sources. (SC-21)

### Architecture and provisioning for name and address resolution service (SC-22)

> **Guidance:** Fault tolerance means at least two name servers in different network locations. Role separation means internal and external name servers are separate, so internal names are not published to the internet.

- The [System owner] shall ensure the systems that together provide name and address resolution service for the organization are fault-tolerant and implement internal and external role separation. (SC-22)

### Session authenticity (SC-23)

> **Guidance:** Session authenticity protects against session hijacking and replay: TLS with certificate validation, session identifiers that are random and expire, and invalidating session identifiers at logout.

- The [System owner] shall ensure the system protects the authenticity of communications sessions. (SC-23)

### Protection of information at rest (SC-28)

> **Guidance:** Protect stored information on servers, in databases and storage services, in backups and on end-user devices. At Moderate and High, SC-28(1) makes the protection cryptographic.

- The [System owner] shall ensure the system protects the [Select one or more: confidentiality; integrity. Typical: confidentiality and integrity] of [Fill in: information at rest requiring protection. Typical: all information stored by the system, including backups]. (SC-28)

### Cryptographic protection (SC-28(1))

> **Guidance:** Encryption at rest protects against lost devices, stolen media and direct access to storage; it does not protect against someone who can sign in to the application. Keep keys apart from the data they protect.

- The [System owner] shall implement cryptographic mechanisms to prevent unauthorized disclosure and modification of [Fill in: information requiring cryptographic protection. Typical: all organizational information] at rest on [Fill in: system components or media requiring cryptographic protection. Typical: servers, databases, storage services, backups, end-user devices and removable media]. (SC-28(1))

### Process isolation (SC-39)

> **Guidance:** Modern operating systems, hypervisors and container platforms provide separate execution domains; this control is usually inherited. Confirm it for any component that does not, such as some embedded or legacy systems.

- The [System owner] shall ensure the system maintains a separate execution domain for each executing system process. (SC-39)

## Review and update

- The [Fill in: an official to manage the system and communications protection policy and procedures. Typical: Chief Information Security Officer] shall review and update this policy [Fill in: the frequency at which the current system and communications protection policy is reviewed and updated. Typical: annually] and following [Fill in: events that would require the current system and communications protection policy to be reviewed and updated. Typical: assessment or audit findings, security incidents or breaches, and changes in applicable laws, executive orders, directives, regulations, policies, standards or guidelines]. (SC-1c.1)
- The [Fill in: an official to manage the system and communications protection policy and procedures. Typical: Chief Information Security Officer] shall review and update the procedures that implement this policy [Fill in: the frequency at which the current system and communications protection procedures are reviewed and updated. Typical: annually] and following [Fill in: events that would require the system and communications protection procedures to be reviewed and updated. Typical: the same events as the policy, and changes to the systems, tools or services the procedures describe]. (SC-1c.2)

### Federal systems

For federal information systems, this policy also carries out the agency's information security responsibilities under the Federal Information Security Modernization Act of 2014 ([44 U.S.C. § 3554](https://uscode.house.gov/view.xhtml?req=granuleid:USC-prelim-title44-section3554&num=0&edition=prelim), Federal agency responsibilities) and [OMB Circular A-130](https://www.whitehouse.gov/wp-content/uploads/legacy_drupal_files/omb/circulars/A130/a130revised.pdf), Appendix I, Responsibilities for Protecting and Managing Federal Information Resources.

- Where the agency's organization-wide policy sets a value for a parameter in this policy, each system shall use that value or a stricter one. (SC-1a.1(b))