Control: 9.4 Ensure the web app has 'Client Certificates (Incoming client certificates)' set to 'On'

Description

Client certificates allow for the app to request a certificate for incoming requests. Only clients that have a valid certificate will be able to reach the app.

The TLS mutual authentication technique in enterprise environments ensures the authenticity of clients to the server. If incoming client certificates are enabled, then only an authenticated client who has valid certificates can access the app.

Remediation

From Azure Portal

Login to Azure Portal using https://portal.azure.com
Go to App Services
Click on each App
Under the Settings section, Click on Configuration, then General settings
Set the option Client certificate mode located under Incoming client certificates is set to Require

From Azure CLI

To set Incoming client certificates value for an existing app, run the following command:

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

Default Value

By default, incoming client certificates will be disabled when a new app is created using the command-line tool or Azure Portal console.

Usage

Run the control in your terminal:

powerpipe control run azure_compliance.control.cis_v150_9_4

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run azure_compliance.control.cis_v150_9_4 --share

SQL

This control uses a named query:

appservice_web_app_incoming_client_cert_on