cis-azure-compute-2-4-3

name	cis-azure-compute-2.4.3
description	Ensure 'Basic Authentication Publishing Credentials' are 'Disabled'
category	cis-azure-compute
version	2.0.0
author	cyberstrike-official
tags	["cis","azure","functions","deployment-slots"]
cis_id	2.4.3
cis_benchmark	CIS Microsoft Azure Compute Services Benchmark v2.0.0
tech_stack	["azure"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

Ensure 'Basic Authentication Publishing Credentials' are 'Disabled'

Description

Basic Authentication Publishing Credentials provides the ability to publish -- or deploy to -- a function app deployment slot 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.

This recommendation applies to function apps using the Consumption, Premium, or Dedicated (App Service) plans, which support deployment slots.

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 function app deployment slot for authenticating users is required.

Audit Procedure

Using Azure Portal

1. Go to App Services or Function App.
2. Click the name of an app.
3. Under Deployment, click Deployment slots.
4. Click the name of a deployment slot.
5. Under Settings, click Configuration.
6. In the General settings pane, under Platform settings, ensure that SCM Basic Auth Publishing Credentials and FTP Basic Auth Publishing Credentials are set to Off.
7. Repeat steps 1-6 for each function app and deployment slot.

Using Azure CLI

Run the following command to list function apps:

az functionapp list

For each function app, run the following command to list deployment slots: