Cis Azure Storage 17.2.2

---
name: cis-azure-storage-17.2.2
description: "Ensure that 'Public Network Access' is 'Disabled' for storage accounts"
category: cis-azure-storage
version: "1.0.0"
author: cyberstrike-official
tags: [cis, azure, storage, storage-accounts, networking, private-endpoints]
cis_id: "17.2.2"
cis_benchmark: "CIS Microsoft Azure Storage Services Benchmark v1.0.0"
tech_stack: [azure]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# 17.2.2 Ensure that 'Public Network Access' is 'Disabled' for storage accounts (Automated)

## Description

Disallowing public network access for a storage account overrides the public access settings for individual containers in that storage account for Azure Resource Manager Deployment Model storage accounts. Azure Storage accounts that use the classic deployment model will be retired on August 31, 2024.

## Rationale

The default network configuration for a storage account permits a user with appropriate permissions to configure public network access to containers and blobs in a storage account. Keep in mind that public access to a container is always turned off by default and must be explicitly configured to permit anonymous requests. It grants read-only access to these resources without sharing the account key, and without requiring a shared access signature. It is recommended not to provide public network access to storage accounts until, and unless, it is strongly desired. A shared access signature token or Azure AD RBAC should be used for providing controlled and timed access to blob containers.

## Impact

Access will have to be managed using shared access signatures or via Azure AD RBAC.

For classic storage accounts (to be retired on August 31, 2024), each container in the account must be configured to block anonymous access. Either configure all containers or to configure at the storage account level, migrate to the Azure Resource Manager deployment model.

## Audit Procedure

### Audit from Azure Portal

1. Go to `Storage Accounts`.
2. For each storage account, under the `Security + networking` section, click `Networking`.
3. Ensure the `Public network access` setting is set to `Disabled`.

### Audit from Azure CLI

Ensure `publicNetworkAccess` is `Disabled`:

```bash
az storage account show --name <storage-account> --resource-group <resource-group> --query "{publicNetworkAccess:publicNetworkAccess}"
```

### Audit from PowerShell

For each Storage Account, ensure `PublicNetworkAccess` is `Disabled`:

```powershell
Get-AzStorageAccount -Name <storage account name> -ResourceGroupName <resource group name> |select PublicNetworkAccess
```

### Audit from Azure Policy

If referencing a digital copy of this Benchmark, clicking a Policy ID will open a link to the associated Policy definition in Azure. If referencing a printed copy, you can search Policy IDs from this URL: https://portal.azure.com/#view/Microsoft_Azure_Policy/PolicyMenuBlade/~/Definitions

- Policy ID: `b2982f36-99f2-4db5-8eff-283140c09693`
- Name: 'Storage accounts should disable public network access'

## Expected Result

The `Public network access` setting is set to `Disabled` for each storage account. In Azure CLI, `publicNetworkAccess` returns `Disabled`. In PowerShell, `PublicNetworkAccess` returns `Disabled`. The Azure Policy 'Storage accounts should disable public network access' shows compliant.

## Remediation

### Remediate from Azure Portal

First, follow Microsoft documentation and create shared access signature tokens for your blob containers. Then,

1. Go to `Storage Accounts`.
2. For each storage account, under the `Security + networking` section, click `Networking`.
3. Set `Public network access` to `Disabled`.
4. Click `Save`.

### Remediate from Azure CLI

Set 'Public Network Access' to `Disabled` on the storage account:

```bash
az storage account update --name <storage-account> --resource-group <resource-group> --public-network-access Disabled
```

### Remediate from PowerShell

For each Storage Account, run the following to set the `PublicNetworkAccess` setting to `Disabled`:

```powershell
Set-AzStorageAccount -ResourceGroupName <resource group name> -Name <storage account name> -PublicNetworkAccess Disabled
```

## Default Value

By default, `Public Network Access` is set to `Enabled from all networks` for the Storage Account.

## References

1. https://docs.microsoft.com/en-us/azure/storage/blobs/storage-manage-access-to-resources
2. https://learn.microsoft.com/en-us/security/benchmark/azure/mcsb-governance-strategy#gs-2-define-and-implement-enterprise-segmentationseparation-of-duties-strategy
3. https://learn.microsoft.com/en-us/security/benchmark/azure/mcsb-network-security#ns-2-secure-cloud-native-services-with-network-controls
4. https://docs.microsoft.com/en-us/azure/storage/blobs/assign-azure-role-data-access
5. https://learn.microsoft.com/en-us/azure/storage/common/storage-network-security?tabs=azure-portal

## Additional Information

This recommendation is based on the Common Reference Recommendation `Ensure public network access is Disabled`, from the `Common Reference Recommendations > Networking > Virtual Networks (VNets)` section.

## Profile

Level 1 | Automated