Well at least someone could log in using Entra ID!

Impressive work!

This makes me wonder if Microsoft’s commitment to long-term support is part of the problem: instead of deprecating these ancient APIs they keep them on life-support, but forget some "regression-test" on how they interact with the shiny new surfaces.

Feels like P0’s Windows Registry talks, most of the vulns weren’t in the new code, they were in the how legacy behaviors interacted with newer features.

failed to properly validate the originating tenant

One wonders whether those who designed all this ever considered what that field in the token is for.

The word "tenant" is also very telling --- you're just renting, and the "landlord" always has the keys.

Absolutely insane. Security so weak, it seems like you discovered an intentional backdoor.

I recently had to deal with Entra ID for the first time to setup Microsoft OAuth for our site and my god why is it so badly designed.

Just creating a tenant is a PITA and you get a default tenant you can't change without paying for Microsoft 365? Then you have subscriptions, Microsoft partners, Enteprise vs individual accounts, etc. All mixed with legacy AD naming and renaming, documentation with outdated screenshots, Microsoft Partners bullshit.

I imagine this paid out quote the bounty; exploited, it's hard to think of a more damning security flaw.

Microsoft, Azure, why am I not surprised?

after 36 years kerberos seems pretty stable, secure, and well supported finally. why do we need Entra?

Wow the keys to all the enterprise castles! That’s wild!

Was there a bounty?

Oh man, I was close with this a few times as I ran powershell in different ISE windows and sometimes copied/pasted things over for different tenants, darn - it really seemed so obvious of an exploit!