Microsoft Entra Conditional Access Bypasses Exposed in Brokered and Resource-Exclusion Flows

Researchers disclosed two separate Microsoft Entra Conditional Access bypasses that could let attackers obtain Microsoft Graph access without the intended controls, including MFA in some cases. NetSPI reported that Nested App Authentication (NAA), also called BroCI, allowed certain brokered application flows to exchange an Azure Portal refresh token for Graph access tokens without Conditional Access enforcement. The issue affected specific clients, including ADIbizaUX and two Microsoft Intune portal extension clients, and was primarily useful as a persistence mechanism after an attacker had already stolen an Azure Portal refresh token through methods such as phishing or adversary-in-the-middle collection. Microsoft classified that issue as medium severity and deployed a fix; post-patch testing returned AADSTS53003 access-blocked errors for the previously successful exchanges.

A separate disclosure showed that Entra policies configured for all resources but with at least one excluded resource could also be bypassed to obtain Graph tokens without the expected Conditional Access checks. The researcher said the gap was broader than Microsoft had publicly documented and warned that some Microsoft first-party applications appeared able to reach Entra ID data through Graph beyond the scopes visible in issued tokens, enabling tenant enumeration and potentially modification where user privileges allowed it. Microsoft later acknowledged the problem and began rolling out baseline scope enforcement changes, with enforcement starting June 15 and an early opt-in option available through the Entra Admin Center; according to the researcher, enabling that enforcement closes the Graph token bypass and restores proper Conditional Access evaluation.