This Microsoft Entra ID Vulnerability Could Have Been Catastrophic

Security researcher Dirk-jan Mollema discovered two vulnerabilities in Microsoft's Entra ID identity platform that could have granted attackers administrative access to virtually all Azure customer accounts worldwide. The flaws involved legacy authentication systems -- Actor Tokens issued by Azure's Access Control Service and a validation failure in the retiring Azure Active Directory Graph API.

Mollema reported the vulnerabilities to Microsoft on July 14. Microsoft released a global fix three days later and found no evidence of exploitation. The vulnerabilities would have allowed attackers to impersonate any user across any Azure tenant and access all Microsoft services using Entra ID authentication. Microsoft confirmed the fixes were fully implemented by July 23 and added additional security measures in August as part of its Secure Future Initiative. The company issued a CVE on September 4.

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