SharePoint Share-Invite Lure from External Tenant (T1566.003)
This rule detects potential phishing attempts where users receive SharePoint sharing invitations or links from external tenants that are not part of the organization's trusted SharePoint environment. It identifies inbound emails from SharePoint notification senders containing URLs to external SharePoint tenants and also flags internal SharePoint sharing events (invitations or anonymous link creations) initiated by accounts whose domain differs from the home tenant. This could indicate an attacker attempting to lure users to malicious external SharePoint sites or using compromised accounts to facilitate external sharing.
Microsoft Sentinel (KQL)
