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Description

The TLS (Transport Layer Security) protocol secures transmission of data over the internet using standard encryption technology. Encryption should be set with the latest version of TLS. App service allows TLS 1.2 by default, which is the recommended TLS level by industry standards such as PCI DSS.

Rationale​

App service currently allows the web app to set TLS versions 1.0, 1.1 and 1.2. It is highly recommended to use the latest TLS 1.2 version for web app secure connections.

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 Minimum TLS Version set to 1.2 under Protocol Settings.

From Azure CLI​

To check TLS Version for an existing app, run the following command:

az webapp config show --resource-group <RESOURCE_GROUP_NAME> --name <APP_NAME> --query minTlsVersion

The output should return 1.2 if TLS Version is set to 1.2 (Which is currently the latest version).

From PowerShell​

List all web apps:

Get-AzWebApp

For each web app run the following command:

Get-AzWebApp -ResourceGroupName <RESOURCE_GROUP_NAME> -Name <APP_NAME> |Select-Object -ExpandProperty SiteConfig

Make sure the minTlsVersion is set to at least 1.2.

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.

Default Value​

By default, TLS Version feature will be set to 1.2 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-tutorial-custom-ssl#enforce-tls-versions
  2. https://learn.microsoft.com/en-us/security/benchmark/azure/mcsb-data-protection#dp-3-encrypt-sensitive-data-in-transit
  3. https://learn.microsoft.com/en-us/security/benchmark/azure/mcsb-network-security#ns-8-detect-and-disable-insecure-services-and-protocols
  4. https://docs.microsoft.com/en-us/powershell/module/az.websites/set-azwebapp?view=azps-8.1.0