9.10 Ensure FTP deployments are Disabled

Information

By default, Azure Functions, Web, and API Services can be deployed over FTP. If FTP is required for an essential deployment workflow, FTPS should be required for FTP login for all App Service Apps and Functions.

Rationale:

Azure FTP deployment endpoints are public. An attacker listening to traffic on a wifi network used by a remote employee or a corporate network could see login traffic in clear-text which would then grant them full control of the code base of the app or service. This finding is more severe if User Credentials for deployment are set at the subscription level rather than using the default Application Credentials which are unique per App.

Impact:

Any deployment workflows that rely on FTP or FTPs rather than the WebDeploy or HTTPs endpoints may be affected.

Solution

From Azure Portal

Go to the Azure Portal

Select App Services

Click on an app

Select Settings and then Configuration

Under General Settings, for the Platform Settings, the FTP state should be set to Disabled or FTPS Only

From Azure CLI
For each out of compliance application, run the following choosing either 'disabled' or 'FtpsOnly' as appropriate:

az webapp config set --resource-group <resource group name> --name <app name> --ftps-state [disabled|FtpsOnly]

From PowerShell
For each out of compliance application, run the following:

Set-AzWebApp -ResourceGroupName <resource group name> -Name <app name> -FtpsState <Disabled or FtpsOnly>

Default Value:

By default, FTP based deployment is All allowed

See Also

https://workbench.cisecurity.org/benchmarks/10624