Description:
Azure Web Apps allows sites to run under both HTTP and HTTPS by default. Web 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.
Rationale:
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.
Impact:
When it is enabled, every incoming HTTP request is redirected to the HTTPS port. This means an extra level of security will be added to the HTTP requests made to the app.
Audit:
From Azure Portal
1. Login to Azure Portal using https://portal.azure.com
2. Go to App Services
3. Click on each App
4. Under Setting section, click on TLS/SSL settings
5. Under the Bindings pane, ensure that HTTPS Only set to On under Protocol Settings
From Azure CLI
To check HTTPS-only traffic value for an existing app, run the following command,
az webapp show --resource-group <RESOURCE_GROUP_NAME> --name <APP_NAME> -- query httpsOnly
The output should return true if HTTPS-only traffic value is set to On.
From PowerShell
List all the web apps configured within the subscription.
Get-AzWebApp | Select-Object ResourceGroup, Name, HttpsOnly
For each web app review the HttpsOnly setting and make sure it is set to True.
Remediation:
From Azure Portal
1. Login to Azure Portal using https://portal.azure.com
2. Go to App Services
3. Click on each App
4. Under Setting section, Click on TLS/SSL settings
5. Under the Bindings pane, set HTTPS Only to On under Protocol Settings section
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.
References:
1. https://docs.microsoft.com/en-us/azure/app-service/app-service-web-tutorialcustom-ssl#enforce-https
3. https://docs.microsoft.com/en-us/powershell/module/az.websites/setazwebapp?view=azps-8.1.0