Cis Azure Compute 2.1.5

Ensure 'FTP State' is set to 'FTPS only' or 'Disabled'

Description

By default, App Service supports deployment over FTP. If FTP is essential for a deployment workflow, FTPS should be enforced for all App Service apps.

If FTPS is not explicitly required, the recommended setting is Disabled.

Rationale

FTP is an unencrypted network protocol that transmits data -- including passwords -- in clear text. The use of this protocol can lead to both data and credential compromise and can present opportunities for exfiltration, persistence, and lateral movement.

Impact

Deployment workflows that rely on FTP or FTPS rather than WebDeploy or HTTPS endpoints may be affected.

Audit Procedure

Using Azure Portal

1. Go to the Azure Portal
2. Select App Services
3. Click on an app
4. Select Settings and then Configuration
5. Under General Settings, for the Platform Settings, the FTP state should not be set to All allowed

Using Azure CLI

List webapps to obtain the ids:

az webapp list

List the publish profiles to obtain the username, password, and ftp server url:

az webapp deployment list-publishing-profiles --ids <ids>

Using Azure PowerShell

List all Web Apps:

Get-AzWebApp

For each app:

Get-AzWebApp -ResourceGroupName <resource group name> -Name <app name> | Select-Object -ExpandProperty SiteConfig

In the output, look for the value of FtpsState. If its value is AllAllowed the setting is out of compliance. Any other value is considered in compliance with this check.

Expected Result

FTP state should be set to FtpsOnly or Disabled, not AllAllowed.

Remediation

Using Azure Portal

1. Go to the Azure Portal
2. Select App Services
3. Click on an app
4. Select Settings and then Configuration
5. Under General Settings, for the Platform Settings, the FTP state should be set to Disabled or FTPS Only

Using 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]

Using Azure 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 state is set to FTPS only.

References

1. https://learn.microsoft.com/en-us/azure/app-service/deploy-ftp
2. https://learn.microsoft.com/en-us/azure/app-service/overview-security
3. https://learn.microsoft.com/en-us/security/benchmark/azure/security-controls-v3-data-protection#dp-4-encrypt-sensitive-information-in-transit
4. https://learn.microsoft.com/en-us/security/benchmark/azure/security-controls-v3-posture-vulnerability-management#pv-7-rapidly-and-automatically-remediate-software-vulnerabilities
5. https://learn.microsoft.com/en-us/rest/api/appservice/web-apps/create-or-update-configuration#ftpsstate
6. https://learn.microsoft.com/en-us/cli/azure/webapp
7. https://learn.microsoft.com/en-us/powershell/module/az.websites/get-azwebapp
8. https://learn.microsoft.com/en-us/powershell/module/az.websites/set-azwebapp

Profile

Level 1 | Automated