> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/appsec-rules/iac-security/public-exposure/appsec2-azure-31.md).

# Azure Virtual Network subnet is not configured with a Network Security Group misconfiguration detect

## Rule Details

|                        |                                      |
| ---------------------- | ------------------------------------ |
| Cortex AppSec Rule ID  | APPSEC2\_AZURE\_31                   |
| Category - Subcategory | Public Exposure - VPC VCN VNet       |
| Provider               | AZURE                                |
| Severity               | LOW                                  |
| Framework              | Terraform, Terraform Plan            |
| Mapped CSPM/KSPM Rule  | 4780e61a-51ac-46ff-822c-421a97b6c96e |

## Impact

This rule checks whether a Virtual Network (VNET) subnet in the Azure environment is configured with a Network Security Group (NSG). The NSG includes rules to allow or deny traffic to a subnet, providing security for the VNET. If a subnet is not associated with an NSG, it may be exposed to potential cybersecurity threats. Therefore, not having a NSG for a VNET subnet is considered a security risk.

## How to Fix

*Resource:* azurerm\_subnet, azurerm\_network\_security\_group, azurerm\_subnet\_network\_security\_group\_association

* *Arguments:* name, subnet\_id

To fix this issue, you need to associate your Azure Virtual Network (VNet) subnet with a Network Security Group (NSG).

The above configuration shows how to create an NSG and attach it to a subnet. Applying policies via Network Security Groups helps to restrict inbound, outbound traffic that is operating to and from resources connected to Azure VNets.

## By associating an NSG to a subnet, you define rules for inbound and outbound traffic. This improves security by ensuring that only allowed traffic is permitted into and out of the subnet. \[source,go]

resource "azurerm\_network\_security\_group" "example" { name = "example-nsg" location = azurerm\_resource\_group.example.location resource\_group\_name = azurerm\_resource\_group.example.name }

## resource "azurerm\_subnet\_network\_security\_group\_association" "example" { subnet\_id = azurerm\_subnet.example.id network\_security\_group\_id = azurerm\_network\_security\_group.example.id }


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