Microsoft deployment blueprint - Address oversharing concerns for your M365 Copilot deployment

Overview: 

In regulated industries, internal oversharing can compromise data integrity and Copilot effectiveness. This episode defines what “Foundational” means for Microsoft 365 E3 customers and outlines actionable steps to mitigate oversharing risks during Copilot deployment.

What Does “Foundational” Mean? 

Foundational deployment focuses on establishing baseline protections using native Microsoft 365 E3 capabilities. It emphasizes manual controls, visibility, and basic automation to reduce oversharing risks. 

Pilot Phase (2–4 Days) 

Goal: Deploy Copilot to a subset of users with access to low-risk content. 

• Identify Popular Sites: Use SharePoint Admin Center to export the top 100 most visited sites. 

• Assess Oversharing: Run SharePoint Advanced Management (SAM) permission state reports and use Purview Content Explorer to identify sensitive information types (SITs). 

• Grant Access: Cross-reference reports to select up to 100 low-risk sites for Copilot access. 

• Enable Restricted SharePoint Search (RSS): Optionally limit Copilot discovery to selected sites. 

• Audit & Protection: Disable “Everyone Except External Users” (EEEU) and enable Microsoft Purview Audit and DLP policies in simulation mode. 

Deploy Phase (2–4 Weeks) 

Goal: Expand Copilot deployment while securing sensitive data. 

• Discover Risks: Use data access governance reports for SharePoint sites, in particular the permission state reports to flag overshared sites and files. 

• Restrict Access: Initiate site access reviews for Data access governance and apply Restricted Access Control (RAC) to critical sites. 

• Privacy Controls: Create and configure sensitivity labels and their policies, mark sites as ‘Private’ to limit sharing. 

• Enforce DLP Policies: Activate enforce-mode DLP policies to restrict sensitive data exposure. 

• Disable RSS: Allow full Copilot experience once protections are in place. 

Operate Phase (1+ Months) 

Goal: Maintain and improve data security practices. 

• Oversight: Automate SAM reports and lifecycle policies to manage permissions and ownerless sites. 

• Remediation: Use Microsoft Purview Portal to manage DLP alerts and apply sensitivity labels. 

• Retention: Implement SharePoint retention/deletion policies to reduce data surface. 

• Site Hygiene: Identify and restrict or delete inactive sites. 

References: 

Microsoft 365 Copilot admin guide for E3 + SAM licenses