SC.L1-3.13.1: Boundary Protection for CMMC Level 1
Boundary protection is your first line of defense against unauthorized access to organizational communications. This CMMC Level 1 control requires you to monitor and control information flowing in and out of your systems at external and key internal boundaries. Without proper boundary controls, sensitive data can leak through undetected.
What this means
This control requires organizations to establish and maintain protective measures at system boundaries—both external (internet-facing) and internal (between critical systems). You must actively monitor all communications crossing these boundaries, control what traffic is allowed, and protect data in transit. This includes implementing firewalls, network segmentation, and monitoring capabilities to detect and prevent unauthorized information flows.
How to comply
- 1.Identify all external boundaries where your systems connect to untrusted networks or the internet
- 2.Map key internal boundaries between systems handling different data classifications or security levels
- 3.Deploy firewalls and network access controls at identified boundaries
- 4.Configure firewall rules to allow only necessary and authorized communications
- 5.Enable logging and monitoring of all traffic at external and key internal boundaries
- 6.Regularly review logs for unauthorized or suspicious communication attempts
- 7.Document all boundary protection mechanisms and access control policies
- 8.Test boundary controls periodically to verify they block unauthorized traffic
Evidence auditors look for
- Firewall configuration documentation with approved rules and deny-by-default policies
- Network architecture diagrams showing system boundaries and protection mechanisms
- Access control lists (ACLs) limiting traffic at external and internal boundaries
- Monitoring and logging records from boundary devices (firewalls, routers, proxies)
- Security event logs showing blocked or flagged communication attempts
- Backup and recovery policies for boundary protection configurations
- Change management records for firewall and network control updates
Frequently asked questions
When will FAQs be available?
The FAQ for this control is currently being prepared.
GRCWatch automatically maps your system boundaries, tracks firewall and network control configurations, and centralizes boundary protection evidence—eliminating manual log review and reducing the time spent proving compliance for SC.L1-3.13.1.
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