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.
Rationale:
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
.
Impact:
Utilizing and maintaining client certificates will require additional work to obtain and manage replacement and key rotation.
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 the Settings section, Click on Configuration, then General settings
5. Ensure that the option Client certificate mode located under Incoming client certificates is set to Require
From Azure CLI
To check Incoming client certificates value for an existing app, run the following command,
az webapp show --resource-group <RESOURCE_GROUP_NAME> --name <APP_NAME> --
query clientCertEnabledThe output should return true if Incoming client certificates value is set to On.
From PowerShell
List all web apps.
Get-AzWebAppFor each web app run the following command.
Get-AzWebApp -ResourceGroup <app resource group> -Name <app name>Make sure the ClientCertEnabled 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 the Settings section, Click on Configuration, then General settings
5. Set the option Client certificate mode located under Incoming client certificates 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=trueDefault Value:
By default, incoming client certificates will be disabled when a new app is created using the command-line tool or Azure Portal console.
References: