Cis Azure Storage 17.4

17.4 Ensure that 'Secure transfer required' is set to 'Enabled' (Automated)

Description

Enable data encryption in transit.

Rationale

The secure transfer option enhances the security of a storage account by only allowing requests to the storage account by a secure connection. For example, when calling REST APIs to access storage accounts, the connection must use HTTPS. Any requests using HTTP will be rejected when 'secure transfer required' is enabled. When using the Azure files service, connection without encryption will fail, including scenarios using SMB 2.1, SMB 3.0 without encryption, and some flavors of the Linux SMB client. Because Azure storage doesn't support HTTPS for custom domain names, this option is not applied when using a custom domain name.

Impact

No specific impact noted. This is a standard security best practice.

Audit Procedure

Audit from Azure Portal

1. Go to Storage Accounts.
2. For each storage account, under Settings, click Configuration.
3. Ensure that Secure transfer required is set to Enabled.

Audit from Azure CLI

Use the below command to ensure the Secure transfer required is enabled for all the Storage Accounts by ensuring the output contains true for each of the Storage Accounts.

az storage account list --query "[*].[name,enableHttpsTrafficOnly]"

Audit from Azure Policy

Policy ID: 404c3081-a854-4457-ae30-26a93ef643f9 - Name: 'Secure transfer to storage accounts should be enabled'

Expected Result

The Secure transfer required setting should be Enabled for all storage accounts. The CLI output should show true for enableHttpsTrafficOnly for each storage account.

Remediation

Remediate from Azure Portal

1. Go to Storage Accounts.
2. For each storage account, under Settings, click Configuration.
3. Set Secure transfer required to Enabled.
4. Click Save.

Remediate from Azure CLI

Use the below command to enable Secure transfer required for a Storage Account:

az storage account update --name <storageAccountName> --resource-group <resourceGroupName> --https-only true

Default Value

By default, Secure transfer required is set to Disabled.

References

1. https://docs.microsoft.com/en-us/azure/storage/blobs/security-recommendations#encryption-in-transit
2. https://docs.microsoft.com/en-us/cli/azure/storage/account?view=azure-cli-latest#az_storage_account_list
3. https://docs.microsoft.com/en-us/cli/azure/storage/account?view=azure-cli-latest#az_storage_account_update
4. https://learn.microsoft.com/en-us/security/benchmark/azure/mcsb-data-protection#dp-3-encrypt-sensitive-data-in-transit

Profile

Level 1 | Automated