Microsoft Graph and Permissions Model

Quick Answer: Microsoft Graph is the unified API for Microsoft 365 data. Copilot retrieves organizational content through Graph using the signed-in user's permissions — it does not bypass SharePoint, OneDrive, or Exchange access controls. The semantic index pre-indexes tenant content respecting those same permissions.

Understanding Microsoft Graph and the permissions model is essential for AB-900 because every Copilot data exposure question ultimately asks: "What can this user already access?" Graph is the bridge between identity, workload permissions, and AI responses.

What Is Microsoft Graph?

Microsoft Graph is a REST API and data platform that exposes Microsoft 365 resources through a single endpoint (https://graph.microsoft.com). It aggregates data from:

Applications — including Microsoft 365 Copilot, custom agents, and third-party integrations — call Graph to read and write M365 data on behalf of a user or as an application.

Delegated vs Application Permissions

Graph supports two permission models. AB-900 focuses on the concepts:

On the Exam: Microsoft 365 Copilot uses delegated permissions through the signed-in user's identity. It cannot surface data the user lacks permission to read. Custom Copilot Studio agents may combine delegated and application permissions depending on configuration — a governance concern for Domain 3.

How Copilot Accesses Data

When a user interacts with Microsoft 365 Copilot:

1. User authenticates through Entra ID (MFA, Conditional Access evaluated).
2. Copilot queries the semantic index and Microsoft Graph for relevant organizational content.
3. Graph returns only resources the user has permission to access in Exchange, SharePoint, OneDrive, and Teams.
4. Copilot synthesizes a response grounded in that permitted content plus optional web grounding (if enabled).
5. DLP and sensitivity labels may further restrict what Copilot can include in generated output.

Copilot does not:

• Grant users access to files they cannot already open.
• Use a hidden Global Admin service account to read all tenant data.
• Override sensitivity label restrictions on protected content.
• Index content from workloads the user has no license for.

The Semantic Index

The semantic index is Microsoft 365's pre-built index of organizational content that enables Copilot to find relevant information quickly:

Common Trap: The semantic index does not fix oversharing. If a file has an "Anyone" link or excessive site membership, the index correctly reflects that the user can access it — and Copilot will too.

Permission Inheritance Chain

AB-900 scenarios often require tracing the permission chain:

Entra ID User Identity
    → Group Memberships (security groups, M365 groups)
        → SharePoint Site Permissions (Owners, Members, Visitors)
            → Document Library / File ACLs
                → Sharing Links (Anyone, Org, Specific people)
                    → Copilot / Graph Query Result

A user in a Team's Members group gets access to the team's SharePoint site. Copilot can then reference files in that site. Removing the user from the Team breaks the chain.

Microsoft Graph and Custom Agents

Microsoft Copilot Studio agents can connect to knowledge sources (SharePoint sites, files, websites, Dataverse) and actions (Power Automate flows). Each connection has permission implications:

Admins govern agent permissions through Power Platform admin center (environment DLP, connector policies) and M365 admin center (Integrated apps, agent approval workflows). AB-900 Domain 3 covers agent lifecycle; Domain 1 requires understanding that agents ultimately query data through Graph or configured connectors.

Integrated Apps and Graph Connectors

The Integrated apps section in the M365 admin center manages third-party and custom integrations:

• Copilot plugins extend Copilot with external data or actions.
• Graph connectors index third-party data (file shares, ServiceNow, etc.) into Microsoft Search/Copilot.
• Admins control which integrations are approved to prevent ungoverned data access.

Each integration requires admin consent for Graph permissions. AB-900 tests that you understand admin consent gates tenant-wide data access for applications.

Graph Permissions Quick Reference for AB-900

Master this table and you can answer most Domain 1 and Domain 2 crossover questions about Copilot data exposure.