Enable network authentication with Azure AD only joined devices & Intune

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Introduction

This post is a brief summary of establishing network connection (wired or wireless network) on Intune managed devices, from my experience.

Challenges

Azure AD only joined devices are not present in Active Directory and therefore certificates can not be issued by the PKI, resulting that clients can not authenticate with a certificate.

Your network is one layer of your security perimeter and should be protected.

Additionally, the configuration must be accomplished with Intune.

Solutions for network authentication

Open (no authentication)

Pre-shared key (password)

Certificate authentication <- this posts focus

User authentication with username + password

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User authentication by providing credentials with SSO will not work if you have Credential Guard activated. It is recommended to move from MSCHAPv2-based connections to certificate-based authentication.

Background: Kerberos unconstrained delegation cloud allow attackers to extract Kerberos keys from the isolated LSA process. NTLMv1 classic authentication is attackable. Learn more from the Microsoft docs

My recommendation is to achieve authentication to your corporate network through certificates, because it is the most secure way. Even though you need some technical prerequisites in place:

Certificate deployment to clients - PKCS or NDES Intune

Network profile configuration deployed from Intune

Trusted Root certificate deployed to your clients (from the CA and authentication service server certificate)

Configuration from your network devices / RADIUS setup

Another challenge is the configuration from the network side. Your clients typically talk EAP (TLS) with the end network device which could be an access point or switch and these then forward the request to a central component, that can handle RadSec or RADIUS protocols in order to validate the authentication request.

There are multiple validation techniques available, depending on the product and vendor. But to verify the request, the network component can do one or more of these checks: