Microsoft 365 Copilot: 5 SharePoint and Tenant Permissions to Audit Before Rollout

When an organisation rolls out Microsoft 365 Copilot, the AI model does not bypass permissions—it strictly respects them.

The problem is that in almost every company, existing SharePoint and OneDrive permissions are far wider than leadership realises.

Before Copilot, sensitive files (like executive salary spreadsheets, M&A proposals, or disciplinary notes) were protected primarily through security through obscurity: they were sitting in a folder that employees simply didn't know existed.

Once Copilot is introduced, a simple natural-language prompt like "Summarise executive compensation discussions from last quarter" will immediately index and surface those files if the user has read permissions.

Here are the five critical access controls to audit and harden before assigning Copilot licenses.

1. Audit "Everyone except external users" Group Grants

The default sharing behavior in many historical SharePoint Online migrations has been to grant read permissions to Everyone except external users.

Copilot indexes every document that an identity has permission to view. If an HR or finance folder was configured with broad group access, every licensed employee now has an AI assistant ready to summarise its contents.

Remediation action:

• Run a PowerShell tenant inventory across all SharePoint site collections to flag libraries granting permissions to Everyone except external users or public Microsoft 365 Groups.
• Transition critical departmental repositories to restricted, role-based private security groups.

2. Restrict Sensitive Sites via SharePoint Advanced Management (SAM)

Microsoft provides SharePoint Advanced Management policies, including Restricted SharePoint Search.

Rather than waiting months to remediate every legacy document across hundreds of sites, you can define an explicit list of approved SharePoint sites that Copilot is permitted to search.

Remediation action:

• Enable Restricted SharePoint Search to limit Copilot's tenant-wide indexing to an approved curated list of intranet and knowledge-base sites while deeper data classification takes place.
• Exclude sensitive finance, legal, and executive site collections until permissions have been explicitly attested by data owners.

3. Implement Microsoft Purview Sensitivity Labels with Auto-Inheritance

Sensitivity labels allow you to enforce encryption, visual watermarking, and access restrictions that travel with the file, regardless of where it is copied or shared.

Copilot automatically respects Purview sensitivity labels. If a user does not hold rights to open a document labeled Confidential - Executive Only, Copilot will not use that document to generate responses.

Remediation action:

• Define clear baseline labels: General, Internal, Confidential, and Highly Confidential.
• Implement auto-labeling rules for documents containing National Insurance numbers, banking details, or specific corporate keywords.

4. Eliminate Stale Anonymous & Organization-Wide Sharing Links

Over years of collaboration, employees routinely generate "Anyone with the link" or "People in your organisation with the link" sharing URLs. These links persist indefinitely unless an expiration policy was enforced.

Copilot treats any file accessible via an active organization-wide link as groundable content for anyone who asks relevant questions.

Remediation action:

• Review and reduce tenant-wide sharing link lifetimes (e.g., expire anonymous links after 14–30 days).
• Run a tenant-level report to revoke orphaned organization-wide links on sensitive document libraries.

5. Govern Third-Party AI Extensions & OAuth Grants

Copilot operates within Microsoft 365, but modern knowledge workers frequently install third-party plugins, browser extensions, and unvetted AI tools that request delegated access to read mail and files.

If users authorise unapproved SaaS applications with Mail.Read or Files.Read.All scopes, corporate data is leaked out of the protected tenant boundary into third-party cloud infrastructure.

Remediation action:

• Enforce Admin Consent Workflows in Microsoft Entra ID (formerly Azure AD).
• Block non-admin users from registering multi-tenant OAuth applications or granting consent to unvetted third-party AI assistants.

Plan Your Copilot Security Assessment

A phased, structured review of your tenant's data governance takes days—not months—and eliminates significant privacy, compliance, and commercial exposure.

• Need an independent audit of your Microsoft 365 or Google Workspace environment?
• Explore our Google Workspace & Microsoft 365 Migration and Tenant Hardening package or discuss your requirements with our team.