> 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 }


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://cortex-docs.paloaltonetworks.com/appsec-rules/iac-security/public-exposure/appsec2-azure-31.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.