(laid off) Microsoft PM here that worked on the patch described as a result of the research from Wiz.
One correction I’d like to suggest to the article: the guidance given is to check either the “iss” or “tid” claim when authorizing multi-tenant apps.
The actual recommended guidance we provided is slightly more involved. There is a chance that when only validating the tenant, any service principal could be granted authorized access.
You should always validate the subject in addition to validating the tenant for the token being authorized. One method for this would be to validate the token using a combined key (for example, tid+oid) or perform checks on both the tenant and subject before authorizing access. More info can be found here:
https://learn.microsoft.com/en-us/entra/identity-platform/cl...