Blocking External Users with Azure Conditional Access

Microsoft Entra Conditional Access, or Conditional Access Policy, provides powerful capabilities to manage and restrict access, especially to external users. In this blog, we’ll look at how to use a BLOCK Conditional Access Policy¹ to prevent external users from accessing resources they shouldn’t see.

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We cover:
1️⃣ What external users can do in your environment by default.
2️⃣ Why a BLOCK policy is essential to your security.
3️⃣ FAQ: Frequently Asked Questions

🔎 What can external users do by default?

When you invite or allow external users to collaborate through Azure AD, they often get more access than you might want, depending on the configuration. This means that, for example:

Azure Portal: Be able to access certain resources as an administrator or via shared links.
PowerShell: be able to access APIs via scripts or command-line tools.

While collaboration is essential, you want to limit unwanted access to protect your data and resources. 💡

🚧 Why a BLOCK Conditional Access Policy?

Remote users play an important role in collaboration, but they also pose risks when they access critical systems¹. A properly configured BLOCK Conditional Access Policy ensures that:

External users cannot access management tools, such as the Azure Management Portal and PowerShell APIs.
You can meet security guidelines by limiting access to what is strictly necessary.
Management becomes easier because you can segment external access without impacting internal users.

✨ What are the benefits of this approach?

Enhanced security: You minimize risk by blocking access to the Azure Management API.
Control: You can control exactly who gets access and to which parts.
Flexibility: External access is restricted without interfering with internal workflows.

FAQ: Frequently Asked Questions🔒

❓ What is conditional access in Azure?

Conditional access in Azure is a policy that defines the conditions under which users can access corporate resources. This helps to increase the security of your environment by restricting access based on specific criteria, such as location, device status or user group.

❓ Does conditional access affect remote users?

Yes, conditional access allows you to restrict or block access for external users. This is critical for protecting sensitive data from unauthorized access by users outside the organization.

❓ How do I set up conditional access in Azure?

Go to the Azure Active Directory Admin Center.
Select Conditional Access and click New Policy.
Define conditions, such as user groups, device status and locations.
Set access controls, for example, allow or block.
Test and activate the policy.

❓ How do I block remote users with conditional access?

Create policies specific to users with guest or remote user status.
Set access controls to block access to specific applications or data.
Implement additional layers of security, such as Multi-Factor Authentication (MFA).

❓ Does conditional access apply to guest users?

Yes, conditional access can be set up to manage guest users, including limiting their access to specific applications or data.

❓ What are the benefits of conditional access in Azure?

Protection of sensitive data from unauthorized access.
Manageable access based on corporate policies.
Flexibility to adapt access rules to specific scenarios.
Additional layers of security, such as enforcing MFA.

❓ Can I test conditional access before applying it?

Yes, Azure provides a What-If tool that allows you to test how a policy would be applied to a specific user or situation before activating it.

🌟 Closure

By understanding the default behavior of remote users in Azure and deploying Conditional Access effectively, you will better protect your environment from unwanted access. A BLOCK Conditional Access Policy is a powerful and simple way to strengthen your security. 🔐 Do you also want an environment that is optimally secured with the right measures? Then take a look at our Modern Workplace page² and find out how we can help you! 🔐✨

¹https://learn.microsoft.com/en-us/entra/architecture/7-secure-access-conditional-access

²https://alta-ict.nl/ModerneWerk

About the author

My name is Alta Martes, a specialist in Microsoft 365 and Google Workspace, with a focus on modern workplace management, cloud security and identity & access management. With years of experience, I help organizations optimize their IT infrastructure and create a secure, efficient digital workplace. 🎯 Need help with your Microsoft 365 strategy?
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