Microsoft’s Entra ID Exposed: Guests Can Seize Admin Rights

Microsoft Entra ID security vulnerability exposes organizations to unauthorized privilege escalation through guest account exploitation

Three Key Facts

• Guest users can create unauthorized subscriptions within Microsoft Entra ID tenants, bypassing standard directory and role-based access controls through billing-level permissions that operate outside typical oversight mechanisms.
• Application Administrator roles enable privilege escalation to Global Administrator status, as discovered by Semperis security researchers who found actions occurring beyond expected OAuth 2.0 authorization controls.
• Microsoft experiences over 1,287 password attacks per second and 5.8 billion monthly breach replay attempts, while 92% of productivity accounts now use phishing-resistant multi-factor authentication as the company phases out legacy authentication by March 2026.

Introduction

Microsoft Entra ID organizations face a previously unrecognized security vulnerability that allows guest users to escalate privileges through subscription manipulation. Security researchers at Semperis have identified critical gaps in access control that enable unauthorized users to gain ownership rights within target tenants.

The vulnerability exploits billing-level permissions that operate beyond standard directory controls. Guest accounts, typically considered low-risk due to restricted access, can leverage home tenant privileges to create subscriptions in target environments where they should maintain limited permissions.

This design flaw challenges conventional security assumptions about guest account limitations. Organizations that rely on standard threat models may overlook these attack vectors, leaving critical infrastructure exposed to lateral movement and privilege escalation attempts.

Key Developments

The Semperis security research team documented a systematic process by which attackers exploit Entra ID’s architecture. The attack begins when threat actors control users with billing roles capable of creating or owning subscriptions, often achieved through Azure free trial accounts that automatically grant billing account owner roles.

Once invited as guests in target tenants, attackers access the Azure Portal through their home directory credentials. They navigate to the “Advanced” tab and designate the defender’s directory as the target for new subscription creation, instantly gaining “Owner” status within the victim environment.

The research reveals that certain Microsoft application service principals perform privileged actions without defined permissions. The Device Registration Service can modify membership in privileged roles, creating additional pathways for privilege elevation that bypass traditional security controls.

Microsoft’s Security Response Center has collaborated with Semperis to address these vulnerabilities. The timeline shows ongoing efforts to patch discovered threats while maintaining system functionality for legitimate business operations.

Market Impact

Identity security investments are accelerating as organizations recognize the financial implications of access control failures. Microsoft’s Entra platform deployment reduces IAM complexity and operational costs while improving security postures across enterprise environments.

The discovery affects organizations using guest account strategies for cost reduction and operational efficiency. Companies that extensively rely on B2B collaboration through Entra ID face immediate review requirements for their current access control implementations.

BeyondTrust’s Identity Security Insights product addresses growing demand for comprehensive identity risk assessment tools. The market responds to increased awareness that identity-based attacks represent more common threat vectors than traditional “hacking in” approaches.

Strategic Insights

The vulnerability highlights fundamental tensions between cloud cost optimization and security controls. Organizations implementing Zero Trust models must reconsider guest account permissions and billing role assignments as part of comprehensive identity governance strategies.

AI-driven security enhancements emerge as both defensive tools and potential attack targets. Microsoft’s Security Copilot automates identity lifecycle management and optimizes conditional access policies, though machine learning assessments of sign-in risks remain susceptible to false positives and negatives.

The shift toward hardware-based authentication methods reflects industry recognition that password-based systems cannot adequately protect against sophisticated identity attacks. Organizations investing in phishing-resistant MFA solutions position themselves advantageously against evolving threat landscapes.

Cloud adoption expansion increases attack surfaces through privilege vulnerabilities. Companies must balance operational efficiency with robust identity-based access controls, particularly as AI applications become both security tools and potential compromise targets.

Expert Opinions and Data

Simon Maxwell-Stewart, Senior Security Researcher at BeyondTrust, emphasizes examining identity misconfigurations as growing attack surfaces beyond traditional administrative security policies. His research underscores the importance of comprehensive access reviews that include guest account activities and subscription governance.

According to The Hacker News, standard security practices typically overlook risks associated with unprivileged guests creating subscriptions, making these threats particularly difficult for security teams to detect through conventional monitoring approaches.

Industry experts stress that attackers more commonly exploit legitimate authentication pathways than technical system vulnerabilities. This observation drives emphasis on identity security as a fundamental business requirement rather than a secondary technical consideration.

Microsoft’s threat intelligence data reveals the scale of identity-focused attacks, with over 5.8 billion password breach replay attempts occurring monthly across their platform ecosystem. These statistics demonstrate the persistent nature of credential-based attack strategies.

Conclusion

Microsoft Entra ID’s guest account vulnerabilities represent systematic risks that require immediate organizational attention and policy adjustments. The ability for guest users to create unauthorized subscriptions and escalate privileges challenges fundamental assumptions about cloud identity security.

Organizations must implement comprehensive auditing of guest accounts, subscription monitoring, and enhanced access controls to mitigate these newly identified threats. The collaboration between security researchers and Microsoft demonstrates ongoing efforts to address identity infrastructure vulnerabilities.

The findings reinforce the critical importance of Zero Trust implementation and least-privilege access principles in modern cloud environments. Companies that fail to address these identity security gaps face significant exposure to sophisticated privilege escalation attacks.