The most common Copilot surprise is not the AI. It is the discovery that a document nobody meant to share has been reachable by the whole company for three years — and Copilot, asked a perfectly innocent question, helpfully found it.
Why this happens
Copilot respects permissions exactly: it can only use what the person asking can already open. But SharePoint and OneDrive accumulate loose permissions over time. "Anyone in the organisation with the link" was clicked once in 2022. A folder inherited access from a site that was open to everyone. A leaver's OneDrive was handed over wholesale. Nothing was breached; Copilot just made the existing state visible.
How to find out before roll-out
- Run a sharing report. Microsoft 365 can list files shared with "everyone" or via organisation-wide links. It is usually a longer list than expected.
- Check site permissions on the sites that hold HR, finance and contracts.
- Look for "Everyone except external users" — a group that quietly appears in permissions and is exactly what it sounds like.
How to fix it
- Restrict sharing defaults so new links are "specific people" rather than "anyone".
- Move sensitive content into sites with deliberate, role-based access.
- Apply sensitivity labels to confidential documents — Copilot honours them and will not surface labelled content to people outside its scope.
- Use restricted search or Copilot's site-exclusion settings for the most sensitive libraries while the clean-up finishes.
Our approach
Before Copilot is enabled for any customer we run this review and fix what it finds — usually a day or two of tidy-up that also improves security regardless of AI. The aim is that the first search a manager runs finds the customer proposal they wanted, and nothing they did not.
