Carmine Punella, a Microsoft Certified Professional, is renowned for his C# expertise, contributions to the Windows 8 App Hall of Fame, and extensive experience in designing scalable, reliable cloud-based platforms.
Implementing least privilege access is one of the most effective and most overlooked ways to reduce security risk and preserve security posture in Microsoft 365. Implementing true least privilege demands more than just trimming permissions; it requires a structured, phased approach that works across Microsoft Entra ID, Exchange Online, SharePoint, OneDrive, Teams, and all the services your workforce touches daily.
This guide walks you through a practical roadmap for rolling out least privilege access (PoLP) in Microsoft 365 environments.
Implementing least privilege in Microsoft 365 is not a single project. It’s a long-term security program. Taking a phased approach, including audit, design, implementation, and governance, this guide explains and breaks down how to apply the principle of least privilege across key Microsoft 365 workloads. You’ll also learn the operational best practices required for ongoing success, and how a specialized platform such as CoreView can automate the entire program.
General steps to implement least privilege access in M365
Implementing the principle of least privilege in Microsoft 365 is essential defense strategy for reducing the blast radius of account compromise, limiting unnecessary exposure of sensitive data, and ensuring users and workloads have only the permissions they need.
In an environment as interconnected as Microsoft 365, (often default) excessive access rights can quickly snowball into serious security and compliance risks. The shift from on-prem networks to the cloud requires a new perspective on security and access management. In Microsoft 365, overly permissive roles, especially within the Azure AD/Entra ID structure, can unintentionally grant access across SharePoint, Exchange, Teams, and OneDrive. By adopting a least privilege model, organizations can strengthen their security while improving operational control.
In the following four-step framework, we’ll walk through exactly how to design, enforce, maintain and monitor least privilege access across Microsoft 365 so you can build a more secure and resilient environment and eliminate your overprivilege problem.
Audit and Discover
The first and most critical step in implementing least privilege is gaining a complete understanding of the current access landscape. It is not possible to secure what you don’t know you have and don’t know who has access to it. This phase is about discovery, assessment and establishing a clear baseline of your current user access and service permissions.
Key steps:
Identify and inventory all privileged accounts Start with global administrators, application administrators, and other highly privileged roles. Catalog user accounts, admin accounts, service principals, legacy authentication clients, and guest/external accounts.
Map roles and permissions Identify which permissions users currently have, especially delegated admin roles, mailbox access, SharePoint permissions, and Teams ownership. You can use Entra ID’s built-in reporting and PowerShell scripts to map which users belong to which admin and non-admin groups.
Identify shadow admins and privilege sprawl Look for dormant roles or inherited permissions that unintentionally grant elevated access. Look out for users who have been granted too much access “just in case” or role bloat. Disable and remove permissions from accounts that have been inactive for a significant period.
Determine required business function For every role or account, document the specific, legitimate business tasks it performs. For example, a help-desk role needs to be able to reset passwords, not manage tenant-wide settings.
Assess high-risk configurations Examples include accounts without MFA, legacy protocols, global admin overuse, and shared admin credentials.
Document business-critical workflows Understanding how teams actually operate helps ensure that you later assign the right minimum permissions, not just the technically minimum ones.
Use Microsoft Purview and Security tools Microsoft Purview Audit lets you review of historical activity logs to help establish who is using what permissions and when.
Define and Architect
Once you understand your privilege landscape, the second phase of least privilege implementation is to build a security architecture rooted in least privilege principles. This move from discovery to active restructuring and policy setting and enforcement.
Key steps:
Leverage role-based access models (RBAC/RBAC++) Define standardized role profiles for admins, power users, and service accounts. This includes just-in-time and just-enough-access roles that enable temporary assignment of admin roles. Privileged Identity Management (PIM) allows users to elevate their privileges to an administrative role only when needed, for example, for a specific duration and only after a formal approval process.
Define access criteria Determine who needs access, why they need it, and for how long. Pair tasks with the least privileged admin roles possible. Because M365 roles are often too broad by default, it’s important to design custom admin roles in Entra ID where possible, which encompass only the specific permissions required for a role/job.
Architect for Zero Trust Incorporate identity-based controls, conditional access, and risk-informed access decisions.
Document approval workflows For privileged access requests, define who approves changes and how requests are logged and reviewed.
Plan for automation Decide what parts of least privilege enforcement can be automated (provisioning, deprovisioning, role assignments, access expiration).
Implement and Enforce
In the third phase of the least privilege implementation process, least privilege becomes operational.
Key steps:
Apply reduced permissions Remove unnecessary roles, excessive group membership, direct resource permissions, and stale admin accounts. This includes limiting (or reducing) the number of global admin accounts to the barest minimum.
Use time-bound or just-in-time access Enable Privileged Identity Management (PIM) to ensure elevated roles are only active when needed.
Harden critical roles Introduce stricter controls for global admins, SharePoint admins, and Exchange admins.
Update provisioning workflows Ensure new employees automatically receive only the permissions required for their job function (not inherited or historical permissions).
Monitor and Govern
Least privilege is not a “set and forget” aspect of maintaining your security posture. Instead, it should be approached as a part of your lifecycle governance process, requiring constant validation and monitoring.
Key steps:
Continuously audit permissions Track role changes, access anomalies, risky sign-in events, and admin activity logs.
Automate periodic access reviews Review access quarterly (or monthly for high-risk groups and resources).
Enforce compliance with policy monitoring Alert or auto-remediate when new accounts are created with excessive permissions.
Measure program maturity through KPIs Examples include number of active global admins, privileged activation frequency, stale accounts, and access-related incident trends.
Integrate with your SIEM and SOAR Make least privilege part of your larger security operations strategy.
Program-specific steps for deploying least privilege access in Microsoft environments
Each Microsoft 365 workload has its own permission model. Below are the high-level tasks you must accomplish in each environment.
Deploying PoLP in Microsoft Entra ID
Microsoft Entra ID is the control plane for the entire Microsoft 365 ecosystem, making it the highest priority for PoLP implementation.
Limit global administrators
Reduce to 2–4 break-glass global admin accounts stored securely. These must be highly protected, used only for emergencies, and their usage must trigger immediate, high-priority alerts.
Convert day-to-day global admins into workload-specific roles. Admins who manage Exchange Online, SharePoint or security policies should be assigned their specific, scoped roles instead of an all-powerful global administrator role.
Require MFA and conditional access for every admin. Enforce not just for sign-in but with strict controls like requiring trusted locations and compliant devices.
Use specific admin roles
Replace broad roles with fine-grained ones such as:
Authentication Admin for managing user credentials and MFA settings
Cloud Application Admin for managing the creation and membership of apps
User Administrator for managing the properties and lifecycle of standard users
Groups Administrator for managing the creation and membership of groups
Manage roles with PIM
Require approval workflows for elevated role activation. Implement a process where a peer or manager must approve the request before the elevated role is granted.
Enforce least privilege through:
Time-bound activation. Roles should be active for the minimum necessary duration and automatically expire.
Justification notes. Require admins to provide specific reasons for role elevation.
Automatic role expiration. Ensure active assignments are temporary.
Monitor PIM logs to identify unusual or frequent activations. High-frequency activation might indicate a need for a standing, lower-privileged custom role, or a user inappropriately using PIM for daily tasks.
Implement conditional access
Require MFA universally. This should be the default policy for all users, regardless of role.
Create targeted policies for:
High-risk users: Block or require password changes/MFA re-registration for users flagged by Entra ID Identity Protection
High-risk sign-ins: Apply stricter controls, like session limits for sign-ins flagged as suspicious
Admin roles only: Enforce the most stringent controls for all admin roles
Unmanaged devices: Block access to sensitive resources from personal or non-corporate devices.
Apply session controls (persistent browser sessions, app-enforced restrictions). For example, you can enforce that users must download content only to managed devices or prevent them from downloading content entirely, forcing them to use the browser-based viewer.
Deploying PoLP in Exchange Online
The mailbox is a prime target for data exfiltration and impersonation, making strict control over Exchange Online permissions vital.
Replace “Organization Management” with smaller role groups. This is the Exchange Online equivalent of a Global Admin. Instead, create role groups for specific tasks.
Audit mailbox delegation (Send As / Full Access). Scrutinize all ‘Send As’ and ‘Full Access’ permissions. These are common vectors for lateral movement and impersonation and should be removed if not actively needed.
Apply mailbox auditing and alerting for abnormal activity. Use auditing for non-owner mailbox access and create alerts for suspicious activities like mass export requests, bulk deletion of items, or access from unusual locations.
Deploying PoLP SharePoint Online
SharePoint holds vast amounts of corporate data, requiring a layered approach to permissions.
Remove “Site Collection Admin” access except where absolutely required. This role grants full control over the site's content and permissions. For most daily operations, lower-level roles like 'Site Owner' or 'Site Member' are sufficient.
Use modern SharePoint admin roles and site-level permissions. Leverage the fine-grained roles available in the SharePoint Admin Center (e.g., SharePoint Administrator, SharePoint Reader) and rely on the modern permissions structure (Owners, Members, Visitors) at the site level.
Eliminate “Everyone” and “Everyone except external users” from high-value sites. This provides excessive broad access. Instead, use specific Entra ID groups (security or Microsoft 365 groups) to grant access explicitly.
Enforce sensitivity labels and DLP policies. Use Microsoft Purview Sensitivity Labels to automatically manage and restrict access to highly confidential documents, often overriding or tightening standard site permissions. Data Loss Prevention (DLP) should be used to monitor and prevent sensitive data from leaving the controlled environment.
Ensure Teams-connected SharePoint sites inherit proper permissions. For sites provisioned via Microsoft Teams, ensure the Team owners are the only ones with site ownership permissions and that guest access settings in the Team are correctly reflected in the SharePoint site's external sharing settings.
Deploying PoLP OneDrive for Business
Personal file storage must be protected from both internal administrators and external threats.
Restrict admin access to individual user drives. Default administrative access to a user's OneDrive should be blocked. Note that this is a process you need to enact rather than an actual function or control to prevent a global admin from gaining access to someone’s OneDrive. Access should only be possible via a strictly controlled process (e.g., using eDiscovery or Content Search) that is fully auditable and requires a specific compliance or legal justification.
Prevent broad eDiscovery of user content. Limit who has permissions to run eDiscovery or Content Search across all user OneDrives. Utilize role groups to scope discovery searches to only the necessary custodians.
Apply conditional access policies for personal storage. Use Conditional Access to enforce strict controls like device compliance or trusted locations specifically for users accessing their OneDrive content, especially for high-value users.
Enforce external sharing restrictions based on sensitivity. Use SharePoint/OneDrive administration controls to prevent anonymous links and limit external sharing to specific domains or approved partners, aligning with the sensitivity of the data stored.
Monitor unusual OneDrive file-sharing or sync activity. Configure alerts for mass file downloads, sharing of numerous files externally, or synchronization of files to a large number of devices, which could indicate a compromise or internal threat.
Deploying PoLP Microsoft Teams
Teams is a collaborative hub that requires least privilege control over group creation, membership, and application access.
Limit who can create teams and Microsoft 365 groups. By default, all users can create groups. Restrict this ability to a small, controlled group of individuals or use an automated provisioning process that enforces governance.
Review and control group owners—no more than 2–3 per team. Having too many owners increases the blast radius if an account is compromised. Clearly defined ownership is essential for managing membership and settings.
Restrict third-party app access and permission scopes. Implement a formal app governance policy. Require that any third-party app requesting access be reviewed and explicitly approved by IT/Security, with its required permission scopes carefully scrutinized and limited to the absolute minimum needed.
Prevent default global access to apps or bots. Utilize the Teams Admin Center to manage which users or groups can install or use specific apps, rather than allowing unfettered access across the entire organization.
Use sensitivity labels to control guest access and external sharing. Apply Microsoft Purview Sensitivity Labels to Teams to automatically manage critical security settings, such as preventing the addition of guest users (external sharing) for sensitive teams and enforcing encryption for meetings.
Best practices for deploying least privilege access in Microsoft environments
Implementing the principle of least privilege is a foundational pillar of a Zero Trust security model in Microsoft 365. This means ensuring that every user and application is granted only the minimum permissions necessary to perform their required tasks, and nothing more.
We know from the 2025 CoreView State of Microsoft 365 Security that while organizations are becoming much more vigilant and careful about assigning admin-level access, they are not as judicious about assigning read-write access to Entra apps. Best practice least privilege means looking at the entire picture for all users and applications.
Continuously monitor all access activities to detect anomalies
Monitoring must be proactive, automated, and near real-time. Anomalies to track include excessive admin role changes, elevation requests, and unusual file-access behaviors.
Security monitoring involves constantly analyzing user and administrator sign-in activities, resource access logs, and configuration changes for unusual or suspicious patterns. Anomalies could include sign-ins from unexpected geographic locations, access attempts outside of normal business hours, bulk data downloads, or unauthorized configuration changes.
A continuous monitoring program allows for near-real-time alerting and automated response to threats. This is critical because standing privileges are a primary target. For instance, if an admin account, even with limited permissions, starts attempting to access the CEO's mailbox, an alert should fire immediately.
Mandate MFA for all accounts
MFA is the foundational control that makes least privilege viable. Admin accounts, in particular, should never authenticate without MFA. MFA requires users to provide two or more verification factors (e.g., a password and a code from an authenticator app) to prove their identity before access is granted.
While MFA should be mandated for all user accounts, it is absolutely critical for any account with administrative privileges (e.g., Global Admin, Exchange Admin, User Administrator). Studies show that accounts with MFA enabled are over 99.9% less likely to be compromised.
Use separate dedicated admin accounts for privileged tasks
Workforce accounts should never be used for administrative actions. Create separate “admin-only” identities governed by strict controls to minimize the risk of a common account compromise escalating into a tenant-wide breach.
Administrators should have a standard, non-privileged user account for day-to-day work (email, web browsing, etc.) and a completely separate account reserved only for administrative tasks.
The administrative account should never be used for email, browsing, or other high-risk, non-admin activities. This prevents the admin's highly privileged credentials from being exposed to typical user threats like phishing emails or drive-by malware downloads. This practice creates a clear delineation of privilege and makes monitoring easier. Best practice further dictates that these dedicated admin accounts should be cloud-native (not synchronized from on-premises AD) and should not have a mailbox.
Automate the Entra ID configuration process through a third-party tool
Automation is essential for avoiding privilege drift, misconfigurations, and manual errors. Leveraging a management and automation platform allows IT to manage user provisioning, de-provisioning, role assignments, and permission changes with predefined, consistent workflows instead of manual, error-prone processes.
Manual processes frequently lead to privilege creep, where users or apps accumulate permissions they no longer need over time. Automated workflows ensure that when a user's role changes, their permissions are automatically updated to reflect the new principle of least privilege for that job function. This also helps with the lifecycle of guest users, ensuring their access expires automatically.
How CoreView helps automate and streamline deploying least privilege access in M365
CoreView provides a purpose-built platform to operationalize, automate, and govern least privilege across all of Microsoft 365. CoreView enhances native Microsoft 365 functionality by providing centralized and granular visibility across your entire tenant. It helps you identify overpermissioned accounts and monitor for configuration drift, and its automation capabilities can trigger automated remediation actions upon detection.
CoreView is also designed to address the overprivilege challenge by enabling functional delegation using Virtual Tenants and custom roles.
Organizations use CoreView to:
Automate provisioning with role-based templates
Enforce least privilege by auto-remediating risky configurations
Replace global admins with scoped, granular virtual admin roles
Execute continuous access reviews with automated workflows
Provide deep audit trails and real-time activity monitoring
Identify and remove shadow admins or excessive permissions
Enforce consistent policies across all M365 workloads
Instead of manually reviewing hundreds of permissions and logs across multiple admin centers, CoreView gives enterprises the tools they need to ensure that least privilege is continuously applied and monitored.
