11/21/2025
Guest accounts pile up fast—and they rarely leave on their own. Here’s a tight, practical baseline:
Do this today
- Discover: Export all guests + external shares (Entra/SharePoint/OneDrive, Google Drive/Groups).
- Expire & attest: Turn on guest expiration and quarterly access reviews (Entra ID Governance / Google reviews).
- Restrict sharing: Org-wide default to “Specific people” links; set domain allow/deny lists for external sharing.
- Limit capabilities:
M365: Conditional Access for guests (MFA, web-only, block download on unmanaged).
Google: Context-Aware Access (device/user/IP levels; view-only for unmanaged).
- Separate external from chat/collab sprawl: Tune Teams external/guest vs B2B Direct Connect; in Google, lock Drive/Chat external permissions by OU/group.
- Monitor: Alert on new guest invites, public links, and dormant guest sign-ins.
Small habit, big supply-chain risk reduction.
When did you last review who outside your org can still log in?