Microsoft Copilot 沿用用戶權限，啟用前須審查過度分享

Disclosure: I co-founded Mitosis Labs, which runs Private SuperIntelligence. This is an adaptation of the original guide written for family offices.

If you run IT for a small organization on Microsoft 365, Copilot changes one thing about your permissions model: it removes the effort it used to take to find things. This post walks through Microsoft's own pre-rollout guidance with the small-tenant case in mind.

The access model in one sentence

From Microsoft Learn: "Microsoft Copilot only surfaces organizational data to which individual users have at least view permissions." The semantic index honors each user's access boundary.

The privacy side is well covered. Microsoft states that prompts, responses and data accessed through Microsoft Graph aren't used to train foundation LLMs, that Copilot services have opted out of Azure OpenAI abuse monitoring with human review, and that Purview sensitivity labels and their usage rights are honored. Microsoft also describes classifiers that help block jailbreak and cross-prompt injection attacks.

So the risk surface is your existing ACLs.

What Copilot can reach

Source	Reach
Email, chats, documents, meetings, calendar, contacts	Anything in Microsoft Graph the user can access
SharePoint and OneDrive	SharePoint permissions, including sharing links
Teams shared channels	Includes access granted to external people
Graph connectors	Third-party data, if the user has permission
Agents	A query built from the prompt, activity history and the user's M365 data, sent to admin-allowed agents
Web search	A generated query sent to Bing

Microsoft's three-step blueprint

1. Remediate oversharing. Use Purview Data Security Posture Management and the SharePoint Advanced Management (SAM) Content Management Assessment to find overshared, ownerless or inactive sites. Apply Restricted Content Discovery to keep sensitive sites out of Copilot while you work. Run site access reviews, remove groups like "Everyone except external users", and fix broken permission inheritance.

2. Set guardrails. Restricted Access Control on business-critical sites, restrict Anyone links and company-wide sharing at tenant level, require sensitivity labels, and add Purview DLP policies so labeled files or sensitive prompts are excluded from Copilot.

3. Meet regulations. Set retention for audit logs and Copilot interactions; use Purview eDiscovery to search and preserve Copilot content.

Licensing notes from Microsoft: SAM is included with Copilot licenses; the blueprint needs at least foundational Purview features in Microsoft 365 E3, with some optimized features in E5 or E7. Viewing the Copilot security dashboard needs Global Reader; changes need AI Administrator.

Two things people miss

Activity history is a record. Prompts and responses (with citations) are stored, searchable via Content search or Purview, and subject to your retention policies. Treat them like email for legal hold.
Processing location. Microsoft routes to the closest regional data centers but may use other regions under high load. EU traffic stays within the EU Data Boundary; outside the EU, queries may be processed in the US, the EU or elsewhere. If admins enable Anthropic models inside Copilot, Microsoft notes they are currently excluded from the EU Data Boundary.

Five questions before you switch it on

Who holds Global Reader and AI Administrator in our tenant?
Which SharePoint sites hold trust, estate or principal documents, and who can open them today?
Have we run an oversharing assessment and turned on Restricted Content Discovery for sensitive sites?
How long do we keep Copilot interactions, and who decided?
Which connectors and agents are allowed, and have we read their terms?

Why this matters more in a family office

A family office tenant can hold trust, estate and principal documents, alongside an old sharing link to an outside accountant or a site for a sold operating company that nobody owns any more. Before Copilot, a junior analyst would have had to go looking for them; with Copilot, a question about "the 2019 trust distributions" can surface them. The audit above is what keeps that answer inside the right audience. We built Private SuperIntelligence as an AI concierge for one family, working across the family's own email, documents and data with citations, within permissions the family sets.

Speak with the founders

Private SuperIntelligence takes a limited number of families at a time so every one gets the same standard of service. Book a private call (ref CPL1-DEV) to talk through your office with Alex Morris.

Prakshal Jain (PJ), Co-founder and CTO, Private SuperIntelligence (by Mitosis Labs)

Alexander Morris, Co-founder and CEO, Private SuperIntelligence (by Mitosis Labs)

Originally published at privatesuperintelligence.si.

Sources (Microsoft Learn, snapshot 2026-10-24): Data, Privacy, and Security for Microsoft Copilot https://learn.microsoft.com/en-us/microsoft-365/copilot/microsoft-365-copilot-privacy; Security for Microsoft Copilot https://learn.microsoft.com/en-us/microsoft-365/copilot/security-microsoft-365-copilot; Secure and governed data foundation for Microsoft Copilot (deployment blueprint) https://learn.microsoft.com/en-us/microsoft-365/copilot/secure-govern-copilot-foundational-deployment-guidance; Configure a secure and governed foundation https://learn.microsoft.com/en-us/microsoft-365/copilot/configure-secure-governed-data-foundation-microsoft-365-copilot.