Beware the Hidden Risk in Your Entra Environment | Guest Account Privilege Escalation Explained

Table of Contents

• What’s Happening Inside Your Microsoft Entra ID?
• How Does This Exploit Work?
• Real-World Example of Guest-Based Entra Exploit
• What Can a Guest Subscription Owner Actually Do?
• Why Is This a Major Concern?
• How to Protect Your Entra Tenant from Guest Subscription Attacks
• Tools That Can Help
• Identity Is the New Perimeter
• Conclusion
•  Frequently Asked Questions (FAQs)

What’s Happening Inside Your Microsoft Entra ID?

While Microsoft Entra ID (formerly Azure AD) has become a core part of modern identity infrastructure, a stealthy threat is lurking within — and it involves guest users. A surprising and under-the-radar risk allows guest users to create subscriptions in their own tenant and transfer them into the target Entra tenant, maintaining full ownership rights in the process.

This behavior — although functioning "as designed" — creates a dangerous privilege escalation path for attackers. Many organizations underestimate guest accounts, assuming they have limited access. But with this vulnerability, an external guest could gain persistent, privileged access into your tenant.

How Does This Exploit Work?

The Exploit in Simple Terms:

• Guest users with billing privileges in their home tenant can:

  
  

  • Create Azure subscriptions

  • Transfer them into your Entra tenant (target)

  • Retain full “Owner” rights to those subscriptions

Why It's Dangerous:

These "guest-made" subscriptions:

• Fall outside traditional Entra or RBAC roles

  
  

• Don’t appear in regular access reviews

• Can be used to hide malicious activities

• Bypass MFA and other tenant-based controls

Real-World Example of Guest-Based Entra Exploit

Here's a step-by-step overview of how attackers can abuse guest access:

What Can a Guest Subscription Owner Actually Do?

This is not just theoretical. Once a guest owns a subscription in your tenant, they can:

View Root Admins

They can list role assignments and see who has Global Admin access — valuable information for further attacks.

Modify or Disable Azure Policies

They can weaken or disable default security policies attached to the subscription, hiding their actions from detection tools.

Create User-Managed Identities

They can introduce user-managed identities tied to the Entra tenant, which:

• Persist beyond the guest's access

• Request elevated permissions

• Mimic legitimate service accounts

Register Trusted Devices

Attackers can register fake compliant devices and bypass Conditional Access Policies — a known exploit path using dynamic device groups.

Why Is This a Major Concern?

Guest subscription creation:

• Bypasses most security team audits

• Exploits billing roles, which are often overlooked

• Doesn’t trigger alerts in Entra role or RBAC reviews

• Affects B2B Entra scenarios (common in enterprise)

Security teams assume “guest” means limited power — this exploit flips that assumption.

How to Protect Your Entra Tenant from Guest Subscription Attacks

1. Block Subscription Transfers by Guests

Use Microsoft’s Subscription Policies to restrict who can create or transfer subscriptions into your tenant. [Reference: Microsoft Docs]

2. Harden Guest Access

• Disable guest-to-guest invitations

• Regularly audit guest accounts

• Remove stale or unused guests

3. Monitor Subscriptions

• Review newly created subscriptions

• Look for unexpected subscription owners

• Track all Security Center alerts, even inconsistent ones

4. Audit Device Enrollment

Especially if you're using dynamic groups to assign access based on device compliance — these can be easily spoofed.

Tools That Can Help

Platforms like BeyondTrust Identity Security Insights offer visibility into:

• Guest-created subscriptions

• Abnormal identity behavior

• Hidden “Paths to Privilege™”

These tools flag the unusual patterns that most native Entra security tools miss.

Identity Is the New Perimeter

In 2025, identity misconfiguration is more dangerous than software exploits. And the growing complexity of cloud identity ecosystems like Entra ID means:

• Every account can be an attack surface

• Every guest can be a potential foothold

• And every misconfigured trust setting can be an open door

Conclusion: Don't Let Guests Rule Your Tenant

What was once considered low-risk access has now become a major attack vector. By understanding this new path to privilege and adjusting your controls accordingly, you can shut the door on one of the most stealthy escalation tactics in modern identity infrastructure.

Rethink guest access today — before attackers exploit it tomorrow.

FAQ:

What is Microsoft Entra ID?

Microsoft Entra ID, formerly known as Azure Active Directory, is Microsoft's cloud-based identity and access management service that helps organizations manage users and secure access to resources.

What is a guest account in Entra ID?

A guest account in Entra ID is a user from an external organization invited to collaborate within a tenant, typically with limited access rights.

How can guest users pose a security threat in Entra?

Guest users can exploit billing permissions from their own tenant to create or transfer subscriptions into a target Entra tenant and gain full ownership of them.

What is the new Entra guest subscription vulnerability?

The vulnerability allows guest users to create subscriptions in their home tenant and move them into the invited tenant, gaining RBAC "Owner" access over those subscriptions.

Why is subscription ownership dangerous?

Subscription ownership allows users to deploy resources, modify permissions, and change security policies, giving them significant control within the tenant.

What roles are commonly overlooked in Entra security?

Billing roles are often overlooked. These roles exist outside typical RBAC and Entra Directory roles but still allow actions like subscription creation and transfer.

Can guest users escalate privileges in Entra?

Yes, by creating subscriptions they own, guest users can gain elevated privileges and visibility into critical tenant components.

What is the impact of guest users modifying Azure policies?

Guest users can disable or weaken security policies within their subscription, hiding malicious activities from security monitoring tools.

How does this attack affect conditional access policies?

By registering trusted devices via compromised subscriptions, attackers can bypass Conditional Access Policies and gain unauthorized access.

What are dynamic device groups in Azure?

Dynamic device groups automatically assign permissions based on device compliance or attributes, which attackers can spoof using this exploit.

What is a user-managed identity in Azure?

It’s a cloud identity tied to an Azure resource that can persist independently and be used to gain further access if created by a malicious actor.

How do attackers get billing roles?

They can create their own Azure tenant using a free trial or compromise an existing user with billing privileges.

Can any guest user invite others into an Entra tenant?

By default, yes. This increases the risk of malicious accounts being invited to escalate access.

How does Microsoft define billing permissions?

Billing permissions are scoped to the billing account and allow users to manage subscriptions, which can be used in this attack path.

Why do many security teams miss this risk?

Because these actions fall outside standard RBAC and Entra Directory roles, and aren’t caught during regular permission reviews.

Can organizations prevent guest subscription transfers?

Yes, Microsoft provides a subscription policy that restricts guest users from transferring or creating subscriptions in the tenant.

What are the signs of a guest-based attack?

Unexpected subscription creation, policy changes, unmanaged devices, or new user-managed identities may indicate guest-based threats.

What tools can detect guest subscription abuse?

Tools like BeyondTrust Identity Security Insights provide visibility into guest-created subscriptions and unusual privilege paths.

What’s the difference between Entra Directory roles and Azure RBAC roles?

Entra Directory roles control identity-related settings, while RBAC roles govern access to Azure resources. Billing roles exist separately from both.

Are B2B tenants more vulnerable?

Yes. In B2B scenarios, tenants are often controlled by different organizations, increasing trust boundaries and attack surfaces.

Is MFA enforced on guest users?

Not always. Because guest authentication is federated through the home tenant, your tenant’s MFA may not apply.

Can attackers use this for lateral movement?

Yes, once inside, attackers can explore lateral paths by listing admin roles and exploiting exposed services.

What are “Paths to Privilege”?

These are hidden or misconfigured access paths that allow a user or attacker to escalate privileges inside a cloud environment.

How can I audit guest access in Entra?

Use the Entra portal to review guest accounts, their permissions, and subscription ownership under role assignments.

What’s a good first step to secure Entra tenants?

Enable the subscription policy to block guest-created subscriptions and conduct a full guest access audit.

Why are identity misconfigurations dangerous?

They often go unnoticed and can be exploited for stealthy, long-term access or privilege escalation.

What are Microsoft’s best practices for guest access?

Limit guest invites, enforce Conditional Access, restrict permissions, and monitor all subscription activity regularly.

Is this exploit theoretical or active?

It’s active. Security researchers and BeyondTrust have observed it being used in real-world environments.

Can attackers hide their actions with this method?

Yes. By disabling policies or using service identities, attackers can stay under the radar of traditional monitoring tools.

How can my organization test for this vulnerability?

Review all active subscriptions, audit owner roles, and use detection tools to identify guest-controlled resources.