How to overcome Azure AD B2C Sign Up accepts tempo

问题:

Azure AD B2C Sign Up user flow accepts temporary email (like mailinator.com) and sends verification code. The Reset Password user flow also behaves similar.

This means a malicious attacker easily can write a script which floods your AD B2C with zillions of users.

Question

Is there any supported way to prevent this, or any idea of workaround(s)?

Reasoning

• Microsoft guards itself against creating Microsoft accounts using temporary emails. (you can not create a Microsoft account using such an email). It is a reasonable security decision. Using B2C you also would like to have a similar guard for your application accounts.

• Implementing the guard logic in your application logic is not a solution, because the train has gone: the account already created.