Jun 12 2019 04:43 AM - edited Jun 12 2019 12:47 PM
After seeing a tweet about a site that could return the tenant identifier for any Azure or Office 365 tenant, I was a tad suspicious. After all, this data should be private - or so you'd think. In fact, the WhatIsMyTenantId.com site simply takes records available to enable OAuth 2.0 sign-ins and extracts the tenant identifier from their content. It's an easy way to get hold of tenant identifiers.
https://www.petri.com/finding-identifier-azure-office-365-tenants
Jun 12 2019 08:21 AM