CMMC Practice Number: SC.L1-3.13.5
CMMC Level: 1 CMMC Domain: Systems and Communications Protections (SC)
Practice Summary:
Implement subnetworks for publicly accessible systems components that are physically or logically separated from internal networks.
Contents:
CMMC Practice Implementation |
Assessment Objectives
Determine if:
[a] publicly accessible system components are identified; and
[b] subnetworks for publicly accessible system components are physically or logically separated from internal networks.
Practice Clarification (DOD, CMU)
Separate the publicly accessible systems from the internal systems that need to be protected. Do not place internal systems on the same network as the publicly accessible systems and block access by default from DMZ networks to internal networks [b].
One method of accomplishing this is to create a DMZ network, which enhances security by providing public access to a specific set of resources while preventing connections from those resources to the rest of the IT environment. Some contractors achieve a similar result through the use of a cloud computing environment that is separated from the rest of the company’s infrastructure [b].
Example
The head of recruiting at your firm wants to launch a website to post job openings and allow the public to download an application form [a]. After some discussion, your team realizes it needs to use a firewall to create a perimeter network to do this [b]. You host the server separately from the company’s internal network and make sure the network on which it resides is isolated with the proper firewall rules [b].
Potential Assessment Considerations
• Are any system components reachable by the public (e.g., internet-facing web servers, VPN gateways, publicly accessible cloud services) [a]?
• Are publicly accessible system components on physically or logically separated subnetworks (e.g., isolated subnetworks using separate, dedicated VLAN segments such as DMZs) [b]?
Where To Look
- System and communications protection policy
- procedures addressing boundary protection
- system security plan
- list of key internal boundaries of the system
- system design documentation
- boundary protection hardware and software
- system configuration settings and associated documentation
- enterprise security architecture documentation
- system audit logs and records
- other relevant documents or records
Who To Talk To
- System or network administrators
- personnel with information security responsibilities
- system developers
- personnel with boundary protection responsibilities
Perform Test On
- Mechanisms implementing boundary protection capability
Additional Information
In cybersecurity, a demilitarized zone (DMZ), sometimes referred to as a perimeter network, is a physical or logical subnetwork that contains and exposes a company’s external-facing services to an untrusted network, usually a larger network such as the internet. The purpose of a DMZ is to add an additional layer of security to a company’s LAN, an external network node can access only what is exposed in the DMZ, and can be intensely managed and audited, while the rest of the company’s network is firewalled.
CMMC Practice Background and References (DOD, CMU) |
Practice Discussion:
DISCUSSION FROM SOURCE: NIST SP 800-171 R2
Subnetworks that are physically or logically separated from internal networks are referred to as demilitarized zones (DMZs). DMZs are typically implemented with boundary control devices and techniques that include routers, gateways, firewalls, virtualization, or cloud- based technologies.
NIST SP 800-41 provides guidance on firewalls and firewall policy. SP 800-125B provides guidance on security for virtualization technologies.
CMMC References:
· FAR Clause 52.204-21 b.1.xi
· NIST SP 800-171 Rev 1 3.13.5
· CIS Controls v7.1 14.1
· NIST CSF v1.1 PR.AC-5
· NIST SP 800-53 Rev 4 SC-7
· UK NCSC Cyber Essentials