The Hidden Subscription Threat in Your Microsoft Entra Environment: What Every Security Team Needs to Know

Imagine this: You’ve locked down your Microsoft Entra environment, reviewed directory roles, and set up strict RBAC policies. You believe your guest accounts are well-contained, with only temporary, minimal access. But lurking beneath these well-laid defenses is a privilege escalation path that can turn even the most unassuming guest account into a high-impact security threat—all thanks to a lesser-known gap in Azure subscription controls.

Welcome to the new reality of identity security in Microsoft Entra, where the most dangerous privilege escalation doesn’t come from a compromised admin, but from a guest user quietly exploiting billing permissions. In this post, we’ll pull back the curtain on this emerging risk, walk you through how it works, and—most crucially—show you how to defend your environment before it’s too late.

Why Guest Accounts in Entra Aren’t as Harmless as You Think

Most security leaders treat guest users as low-risk. After all, guests are supposed to have sharply limited, temporary access—right? Unfortunately, that assumption is now dangerously outdated.

Here’s the hidden risk: A guest user, with the right billing permissions in their home Microsoft Entra tenant, can create or transfer Azure subscriptions into your environment and retain full “Owner” rights over them. This isn’t an obscure bug or a misconfiguration—it’s a flaw in how Azure handles billing roles versus directory and RBAC roles.

Why does this matter? Because this loophole can allow unprivileged guests to create persistent, privileged footholds in your tenant without ever touching your admin roles or showing up in typical permission audits.

Understanding the Privilege Escalation Path: How Guest Subscription Attacks Work

Let’s break down this attack, step by step, so you can see exactly why it’s so dangerous—and so easy to miss.

1. The Guest User’s Starting Point

The attacker begins with one of two things:

Ownership of a billing account in their own home tenant (this is surprisingly easy: simply spin up a new Azure tenant using a free trial, which grants the account owner full billing privileges).
Compromised credentials of someone else with those billing rights.

2. Gaining Entry as a Guest

The attacker receives an invite to become a guest user in your Entra tenant. By default, any user—including guests—can invite other users. This is a classic example of a small setting with big consequences.

3. Creating a Subscription in Your Tenant

Using the Azure Portal: 1. The guest logs into their home tenant (where they have billing control). 2. Under “Subscriptions,” they click “Add +”. 3. In the “Advanced” tab, they select your directory as the target tenant. 4. The subscription is created—not in the attacker’s tenant, but within yours. 5. The guest user is immediately assigned the Owner RBAC role for that subscription, granting them sweeping powers.

All of this happens without requiring admin consent in your tenant, and it won’t trigger most directory role alarms.

4. Stealthy Privilege Escalation

With that “Owner” role over the new subscription, a guest can: – View powerful accounts in your management hierarchy. – Modify or disable Azure security policies for their subscription. – Create persistent identities that survive even if the original guest account is removed. – Register devices and abuse Conditional Access policies.

And because this attack leverages billing-level permissions—often outside the scope of most security reviews—these new subscriptions (and the access they enable) can go undetected for months.

Why This Azure Subscription Loophole Slips Past Most Defenses

To understand why this attack is so stealthy, let’s look at how permissions are typically managed in Azure:

The Three Permission Realms

Entra Directory Roles: Control identity management (e.g., Global Administrator).
Azure RBAC Roles: Grant access to resources (e.g., Owner, Reader, Contributor).
Billing Roles: Govern who can create, transfer, or manage subscriptions—but these are assigned at the billing account level, not within the Entra directory or Azure RBAC context.

Most security teams focus almost exclusively on Directory and RBAC roles, overlooking billing roles entirely. That’s like locking every door in your house but leaving a side gate wide open.

Here’s why that matters: A guest with a home-tenant billing role can “bring their own subscription” into your environment, sidestepping every Entra role review in the process.

Curious about how Azure’s billing model works? Microsoft’s documentation on Azure billing roles is a great place to start.

Real-World Attack Scenarios: What a Restless Guest Can Actually Do

Let’s get practical. What could an attacker accomplish after gaining “Owner” rights over a new subscription in your tenant?

1. Exposing High-Value Accounts

The guest Owner can view “Access Control (IAM)” role assignments for their new subscription. If your root management group admins are inherited down, those privileged identities become visible—even if guests normally can’t list users. This hands attackers a shopping list of your most important accounts.

2. Disabling Security Controls

With Owner rights, the attacker can alter or remove Azure Policies for their subscription. That means they can suppress security alerts or configure risky resources (e.g., open storage accounts or misconfigured VMs) with very little oversight.

3. Creating Persistent Cloud Identities

By creating a User-Managed Identity in their subscription, the attacker can: – Give it additional permissions—sometimes beyond the subscription. – Use it as a stealthy backdoor, surviving the deletion of the original guest account. – Launch phishing-style consent grant attacks, tricking admins into escalating its privileges.

(Want to understand managed identities? Check Microsoft’s official documentation for more.)

4. Abusing Device Registration and Conditional Access

The attacker can register devices to your Entra directory, which can then appear as “compliant.” If your organization uses dynamic groups or device-based Conditional Access policies (“all compliant devices get X”), the attacker could gain access to sensitive systems or resources.

Why does this matter? Because device-based attacks are notoriously hard to spot, especially when blended with legitimate workflows. Conditional Access best practices from Microsoft outline how device compliance can be a weak link if not properly managed.

The Scope of the Problem: Why This Attack Path Is Growing

This isn’t a theoretical risk. Security researchers—including those at BeyondTrust, who uncovered this gap—have observed real-world attacks exploiting guest subscription creation.

Here’s why this threat is multiplying: – B2B Collaboration is on the rise. Many companies now invite hundreds or thousands of guests from partner organizations. – Self-service tenant creation (via Azure Free Trial, for example) puts billing-owner capabilities in many hands. – Default settings often allow guests to invite other guests, and don’t restrict subscription creation. – Most security tooling ignores billing roles and focuses on traditional Entra or RBAC assignments.

This means attackers have more opportunities, with less risk of detection.

Why Typical Azure Security Models Miss This Threat

Let’s be honest: Most Azure security playbooks don’t even consider the possibility of a guest user creating a subscription. They focus on: – Directory role reviews – RBAC assignments audits – Resource-level access controls – Conditional Access enforcement

But because the guest’s route to privilege is through the billing account, none of these controls will show the new subscription or its Owner. It’s an “invisible” risk—until something goes wrong.

If your environment leverages Entra ID B2B Guest features, this path exists unless you’ve explicitly closed it. Most organizations are simply unaware.

How to Defend Against Guest-Made Subscription Attacks: Practical Mitigations

You’re probably wondering: How do I close this gap in my own environment? Fortunately, there are steps you can take right now.

1. Block Guest Subscription Transfers

Microsoft now allows you to configure a Subscription Policy that blocks guests from bringing subscriptions into your tenant. This is the single most effective defense.

How to enable it: See Microsoft’s official documentation on subscription restrictions.

2. Audit and Harden Guest Access

Review all guest accounts regularly. Remove those that no longer need access.
Restrict guest-to-guest invitations by disabling or tightly controlling who can invite new users.
Harden Conditional Access for guests. Require MFA, restrict device registration, and audit dynamic group memberships.

3. Monitor for Unusual Subscriptions and Resources

Regularly review all subscriptions in your tenant. Look for subscriptions owned by guest accounts or those created unexpectedly.
Monitor Azure Security Center for alerts—while imperfect, it may catch unusual activity.
Audit device registrations, especially if device compliance is tied to access.

4. Modernize Your Threat Model

Expand your threat models to include billing roles and subscription management risks.
Integrate guest subscription detection into your SIEM or identity security solution.

5. Leverage Automated Tools

Products like BeyondTrust Identity Security Insights offer built-in detection for guest-created subscriptions, providing visibility that’s otherwise hard to achieve.

Identity Security: The New Attack Surface

Let me put this bluntly: Identity misconfigurations are the new exploits.

Attackers are patient, creative, and increasingly focused on identity pathways rather than traditional network vulnerabilities. Every overlooked default, every misconfigured guest invitation policy, and every unmonitored subscription is an open door.

Here’s what you can do today: – Revisit your guest access and billing role policies. – Prioritize identity governance and visibility. – Stay informed about emerging attack paths.

The organizations that adapt fastest to these identity-centric risks will be the ones least likely to fall victim to the next wave of attacks.

Frequently Asked Questions (FAQ): Guest Subscription Risk in Entra

1. Can a guest user really create a subscription in my Entra tenant without my approval?

Yes—if the guest has the right billing role in their home tenant and your tenant hasn’t explicitly blocked subscription transfers from guests, they can create or transfer a subscription and become its Owner in your environment.

2. How do I know if there are guest-owned subscriptions in my tenant?

Regularly audit your Azure subscriptions. Check the “Owner” role assignments for each subscription and flag any that are assigned to guest (external) user accounts.

3. What’s the difference between Directory Roles, RBAC Roles, and Billing Roles in Azure?

Directory Roles: Control identity management within the Entra tenant (e.g., Admins).
RBAC Roles: Control access to Azure resources and subscriptions.
Billing Roles: Control the ability to create, transfer, and manage subscriptions, and are assigned at the billing account (not directory) level.

4. How do I block guest users from transferring subscriptions into my tenant?

Configure the “Restrict Subscription Transfer” policy in your Azure portal, as described in Microsoft’s guidance.

5. Is this risk present in all Entra tenants, or only certain configurations?

Any Entra tenant that allows guest invitations and hasn’t restricted subscription transfers is potentially vulnerable, especially if it operates in a B2B context.

6. What tools can help me detect and manage this risk?

Identity security platforms like BeyondTrust Identity Security Insights and robust auditing within Azure Security Center can help, but manual reviews are still essential.

Key Takeaway: Rethink Your Guest Access and Billing Security—Now

Guest accounts are no longer “low risk” by default. The ability for a guest with billing permissions to create or transfer subscriptions into your tenant is a blind spot—one that attackers are already exploiting in the wild.

Your next steps: – Audit your guest users and subscriptions. – Harden your invitation and billing policies. – Leverage modern identity security solutions for visibility. – Stay educated and proactive—this is an evolving threat landscape.

Don’t wait until an attacker uses this hidden door to compromise your environment. Take action today to secure your Entra tenant from this stealthy privilege escalation risk.

For more expert guidance and a free assessment of your identity security posture, explore BeyondTrust’s Identity Security Risk Assessment. And if you found this article helpful, consider subscribing for future deep dives on emerging cloud security challenges.

This article was contributed by Simon Maxwell-Stewart, Senior Security Researcher at BeyondTrust. Simon has over a decade of experience advancing identity security, with a track record of uncovering and mitigating hidden privilege escalation risks in the world’s largest cloud platforms.

Further Reading: – Microsoft Docs: Azure Subscription and Service Limits, Quotas, and Constraints – Azure Security Best Practices – BeyondTrust: Identity Security Insights Overview

Stay secure, stay curious—and always look for the hidden paths to privilege in your environment.

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The Hidden Subscription Threat in Your Microsoft Entra Environment: What Every Security Team Needs to Know

Why Guest Accounts in Entra Aren’t as Harmless as You Think