Cis Azure Compute 2.1.4

Ensure 'Basic Authentication Publishing Credentials' are 'Disabled'

Description

Basic Authentication Publishing Credentials provides the ability to publish -- or deploy to -- an App Service app without a centralized Identity Provider. For a more effective, capable, and secure solution for Identity, Authentication, Authorization, and Accountability, a centralized Identity Provider such as Entra ID is strongly advised.

Rationale

Basic Authentication introduces an identity silo for privileged access to a resource and produces logging which may not provide a full chain of accountability. This can be exploited in numerous ways and represents a significant vulnerability and attack vector.

Impact

Disabling 'Basic Auth Publishing Credentials' will prevent the following deployment methods from working:

FTP Basic Auth Publishing Credentials:

• FTP
• FTPS

SCM Basic Auth Publishing Credentials:

• Local Git
• GitHub
• Azure Repos
• Bitbucket
• Visual Studio (Version 17.12 and earlier)

If this recommendation cannot be implemented because one of the above listed deployment methods is necessary and cannot be adapted, compensating controls (e.g. using FTPS Only and disabling only "SCM Basic Auth Publishing Credentials") are recommended to reduce potential attack surface.

An Identity Provider that can be used by the App Service app for authenticating users is required.

Audit Procedure

Using Azure Portal

1. Search for, and open App Services from the search bar.
2. For each App Service listed:
3. Click on the App Service name.
4. Under the Settings menu item, click on Configuration
5. Under the General settings tab, scroll down to locate the two Basic Auth settings:
   • SCM Basic Auth Publishing Credentials
   • FTP Basic Auth Publishing Credentials

Both radio buttons should indicate a status of Off. Repeat this procedure for each App Service.

Using Azure CLI

Run the following command to list apps:

az webapp list

For each app, run the following command to get the basic authentication for FTP setting:

az resource show --resource-group <resource-group-name> --name ftp --namespace Microsoft.Web --resource-type basicPublishingCredentialsPolicies --parent sites/<app-name> --query properties.allow

Ensure that false is returned.

For each app, run the following command to get the basic authentication for SCM setting:

az resource show --resource-group <resource-group-name> --name scm --namespace Microsoft.Web --resource-type basicPublishingCredentialsPolicies --parent sites/<app-name> --query properties.allow

Ensure that false is returned.

Using Azure PowerShell

Not specifically documented for this control.

Expected Result

Both FTP and SCM basic authentication publishing credentials should return false (disabled).

Remediation

Using Azure Portal

1. Search for, and open App Services from the search bar.
2. For each App Service listed:
3. Click on the App Service name.
4. Under the Settings menu item, click on Configuration
5. Under the General settings tab, scroll down to locate the two Basic Auth settings:
   • Set the SCM Basic Auth Publishing Credentials radio button to Off
   • Set the FTP Basic Auth Publishing Credentials radio button to Off

CAUTION: The new settings are not yet applied. Applying them may cause your App Service resource to restart - proceed with caution. Click the Save button, then click Continue to apply the updated configuration. Repeat this procedure for each App Service.

Using Azure CLI

For each app requiring remediation, run the following command to disable basic authentication for FTP:

az resource update --resource-group <resource-group-name> --name ftp --namespace Microsoft.Web --resource-type basicPublishingCredentialsPolicies --parent sites/<app-name> --set properties.allow=false

For each app requiring remediation, run the following command to disable basic authentication for SCM:

az resource update --resource-group <resource-group-name> --name scm --namespace Microsoft.Web --resource-type basicPublishingCredentialsPolicies --parent sites/<app-name> --set properties.allow=false

Using Azure PowerShell

Not specifically documented for this control.

Default Value

Basic authentication is disabled by default.

References

1. https://learn.microsoft.com/en-us/azure/app-service/configure-basic-auth-disable
2. https://learn.microsoft.com/en-us/cli/azure/webapp
3. https://learn.microsoft.com/en-us/cli/azure/resource

Profile

Level 1 | Automated