Control: Azure > CIS v5.0 > 2 - Analytics Services > 2.01 - Azure Databricks > 2.01.02 - Ensure that network security groups are configured for Databricks subnets

Configures auditing against a CIS Benchmark item.

Level: 1

Network Security Groups (NSGs) should be implemented to control inbound and outbound traffic to Azure Databricks subnets, ensuring only authorized communication. NSGs operate using a rule-based model that includes both explicit allow/deny rules and an implicit deny at the end of the rule list. This means that any traffic not explicitly allowed is automatically denied. To ensure secure and predictable behavior, NSGs should be configured with explicit deny rules for known unwanted traffic, in addition to the default implicit deny, to improve visibility and auditability of blocked traffic. This approach helps enforce least privilege and minimizes the risk of unauthorized access to Databricks resources.

Using NSGs with both explicit allow and deny rules provides clear documentation and control over permitted and prohibited traffic. While Azure NSGs implicitly deny all traffic not explicitly allowed, defining explicit deny rules for known malicious or unnecessary sources enhances clarity, simplifies troubleshooting, and supports compliance audits. This layered approach strengthens the security posture of Databricks environments by ensuring only essential communication is permitted.