PCI DSS 1.4.1: Implementing Network Segmentation Controls
Network segmentation controls (NSCs) are critical firewalls that isolate your cardholder data environment from untrusted networks. This control ensures that sensitive systems remain protected by requiring explicit security measures at network boundaries. Meeting PCI DSS 1.4.1 prevents lateral movement of threats and limits exposure of payment card data.
What this means
Network segmentation controls create explicit boundaries between trusted networks (containing cardholder data) and untrusted networks (like the internet or guest networks). NSCs enforce strict access rules, requiring that all traffic between these zones passes through defined security checkpoints. This prevents unauthorized devices and users from directly accessing systems that store, process, or transmit payment card data.
How to comply
- 1.Map your network architecture to identify all trusted zones containing cardholder data and untrusted external networks
- 2.Deploy firewalls or equivalent security devices at all network boundaries between trusted and untrusted environments
- 3.Configure NSCs with explicit allow rules that permit only necessary traffic based on documented business requirements
- 4.Implement network access control lists (ACLs) that default to denying traffic and explicitly permit only approved connections
- 5.Monitor and log all traffic crossing network segmentation boundaries for audit and threat detection
- 6.Test NSC effectiveness regularly through vulnerability scans and penetration tests to verify proper isolation
- 7.Document all NSC rules, configurations, and business justifications for each permitted connection
Evidence auditors look for
- Firewall configuration files showing explicit rules between trusted and untrusted networks
- Network diagrams documenting the location of NSCs and traffic flow between security zones
- Access control lists (ACLs) with deny-all defaults and specific allow rules for business-critical traffic
- Firewall logs showing traffic filtering and denied connection attempts
- Network segmentation testing reports demonstrating successful isolation of cardholder data environments
- Vulnerability assessment reports confirming NSCs prevent unauthorized lateral network movement
- Change management records for all NSC rule modifications with business justification
Frequently asked questions
When will FAQs be available?
The FAQ for this control is currently being prepared.
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