Network security groups should limit inbound UDP port 137 access from the internet
The Trivy check `AZU-0047` states that a security group rule should not allow unrestricted ingress from any IP address, meaning a rule that permits inbound traffic from every source address does not meet the expectation set by the check.
Opening up ports to allow connections from the public internet is generally to be avoided. You should restrict access to IP addresses or ranges that are explicitly required where possible.
What this control checks
Security group rules must not allow unrestricted ingress from any IP address.
Audit evidence
Evidence that deployed resources meet this control: PowerPipe control azure_compliance.control.network_security_group_restrict_inbound_udp_port_137.
Scans of the Terraform code that flag the same setting before deployment: Trivy check AZU-0047.
Related controls
Tool mappings
Use these identifiers to cross-reference this control across tools, reports, and evidence.
- Compliance.tf Control:
network_security_group_restrict_inbound_udp_port_137 - Powerpipe Control:
azure_compliance.control.network_security_group_restrict_inbound_udp_port_137 - Trivy Check:
AZU-0047
Last reviewed: 2026-10-13