Control: 9.1 Ensure 'HTTPS Only' is set to `On`

Description

Azure App Service allows apps to run under both HTTP and HTTPS by default. Apps can be accessed by anyone using non-secure HTTP links by default. Non-secure HTTP requests can be restricted and all HTTP requests redirected to the secure HTTPS port. It is recommended to enforce HTTPS-only traffic.

Enabling HTTPS-only traffic will redirect all non-secure HTTP requests to HTTPS ports. HTTPS uses the TLS/SSL protocol to provide a secure connection which is both encrypted and authenticated. It is therefore important to support HTTPS for the security benefits.

Remediation

From Azure Portal

1. Login to Azure Portal using https://portal.azure.com.
2. Go to App Services.
3. For each App Service.
4. Under Setting section, click on Configuration.
5. Under the General Settings tab, set HTTPS Only to On under Platform Settings.

From Azure CLI

To set HTTPS-only traffic value for an existing app, run the following command:

az webapp update --resource-group <RESOURCE_GROUP_NAME> --name <APP_NAME> --set httpsOnly=true

From Powershell

Set-AzWebApp -ResourceGroupName <RESOURCE_GROUP_NAME> -Name <APP_NAME> -HttpsOnly $true

Default Value

By default, HTTPS-only feature will be disabled when a new app is created using the command-line tool or Azure Portal console.