Access Reviews in Microsoft Entra: A Comprehensive Guide

Introduction: Why Access Governance Matters

In the modern digital landscape, the perimeter of an organization is no longer defined by a physical office or a protected local network. Instead, the identity of a user—their account, their permissions, and their behavior—has become the new security boundary. As organizations adopt cloud-based applications, collaborative tools, and hybrid work environments, the number of permissions granted to users grows exponentially. Over time, this leads to "permission creep," a phenomenon where employees retain access rights long after they are necessary for their job functions.

Access Reviews within Microsoft Entra (formerly Azure Active Directory) are a critical governance mechanism designed to solve this problem. They provide a structured, repeatable, and automated way to audit who has access to what, and more importantly, whether that access should still exist. By implementing Access Reviews, organizations can significantly reduce the risk of unauthorized access, ensure compliance with regulatory requirements, and maintain a "least privilege" security posture. This lesson explores the mechanics of Access Reviews, how to deploy them, and how to integrate them into a broader security strategy.

Understanding the Core Concepts of Access Reviews

At its heart, an Access Review is a process where an administrator or a designated business owner confirms whether a specific user or group still requires access to a resource. This could be a Microsoft 365 group, an application in the Entra ID portal, or a specific Azure role. Without these reviews, permissions tend to accumulate indefinitely, creating a massive attack surface that could be exploited if a user account is compromised.

Access Reviews operate on a lifecycle model. You define a scope, select who performs the review, set the duration, and decide what happens to the access if the reviewer fails to take action. This automated lifecycle ensures that the process is not just a one-time audit, but a continuous cycle of verification.

Key Components of an Access Review

To effectively use Access Reviews, you must understand the following building blocks:

• Reviewers: These are the people responsible for deciding if access is still appropriate. You can assign the user themselves (self-review), their manager, a specific group owner, or a designated administrator.
• Scope: This defines what is being reviewed. It could be members of a security group, users assigned to a specific SaaS application, or users assigned to a privileged Entra role.
• Recurrence: Access Reviews are most effective when they happen periodically. You can configure them to run monthly, quarterly, or annually to ensure that permissions are constantly audited.
• Automation: You can configure the system to automatically revoke access if a reviewer denies the request or fails to respond within the designated window.

Callout: Access Reviews vs. Privileged Identity Management (PIM) While Access Reviews and PIM both fall under the umbrella of identity governance, they serve different purposes. PIM is focused on "just-in-time" access to highly sensitive roles, where a user must request elevation for a limited window. Access Reviews, conversely, are focused on "just-enough" access, ensuring that the permanent permissions a user holds are still valid and necessary for their ongoing job role.

The Business Value of Regular Auditing

Why should an organization invest the time and effort to configure Access Reviews? The benefits extend beyond simple security hygiene. First, there is the compliance aspect. Many regulatory frameworks, such as GDPR, HIPAA, or SOC2, require organizations to periodically review and document who has access to sensitive data. Automating this via Entra ID provides an audit trail that satisfies auditors without requiring manual spreadsheet tracking.

Second, Access Reviews reduce the operational burden on IT departments. Instead of IT staff manually checking lists of users and guessing if they still need access, the responsibility is shifted to the business owners who actually understand the day-to-day requirements of their teams. This decentralization of governance ensures that decisions are made by those with the most context.

Third, it helps in cleaning up "stale" accounts. Users often move between departments or leave the organization entirely. While automated lifecycle management (like account disabling) is the first line of defense, Access Reviews act as a safety net to catch permissions that might have been granted manually or through secondary processes.

Setting Up Your First Access Review

Setting up an Access Review in the Microsoft Entra admin center is a straightforward process, but it requires careful planning to avoid "review fatigue," where reviewers are overwhelmed by too many requests.

Step-by-Step Configuration

1. Navigate to Identity Governance: Log into the Microsoft Entra admin center and select Identity Governance from the left-hand menu.
2. Create a New Access Review: Select Access reviews and then click New access review.
3. Define the Scope: Choose what you want to review. You can select "Teams + Groups" to review members of a specific group, or "Applications" to review users assigned to a particular enterprise app.
4. Select Reviewers: This is a crucial step. For most scenarios, selecting "Manager" is the best practice, as they have direct oversight of the user’s work. You can also select "Group owners" or specific users if the manager is not available.
5. Configure Settings: Set the duration of the review (e.g., 14 days) and choose what happens if no action is taken. A common best practice is to "Remove access" for non-responsive reviews if the security policy is strict.
6. Enable Recurrence: Set the review to occur on a schedule. Quarterly is a common starting point for most organizations.

Note: Be cautious when setting up "Auto-apply" features. If you choose to automatically remove access, ensure that your reviewers are well-informed about the timeline so they do not accidentally revoke access for critical business users.

Practical Examples and Scenarios

To illustrate the power of Access Reviews, let’s look at three common real-world scenarios.

Scenario 1: Reviewing Guest Users

Guest users are a common source of risk. They often gain access to specific SharePoint sites or Teams, and that access is forgotten long after the project is finished. By creating an Access Review specifically for "All Guest Users" in your directory, you can force project leads to confirm every quarter whether their external collaborators still need access.

Scenario 2: Privileged Role Reviews

For highly sensitive Entra roles (like Global Administrator or Security Administrator), you should implement a monthly review. Because these roles grant immense power, the review should be performed by a high-level security officer rather than a direct manager. This ensures that only those who absolutely need these powers retain them.

Scenario 3: SaaS Application Access

If your organization uses SaaS apps like Salesforce or Slack, you can use Access Reviews to audit user assignments. If a user is assigned to the application via an Entra group, the Access Review will audit the group membership. If they are assigned directly, the review will audit the direct assignment. This ensures that as users change roles, they lose access to apps they no longer use.

Integrating Access Reviews with Automation (Graph API)

While the user interface is excellent for most tasks, you may need to programmatically manage Access Reviews if your organization has thousands of groups or applications. Microsoft Graph API allows you to automate the creation and tracking of these reviews.

Example: Creating an Access Review via PowerShell/Graph

To create an Access Review using the Microsoft Graph PowerShell SDK, you first need to define the review definition object. Here is a simplified code snippet to illustrate how this is structured:

# Define the parameters for the Access Review
$params = @{
    displayName = "Quarterly Review for Finance App"
    description = "Reviewing access to the Finance SaaS Application"
    reviewType = "AccessReview"
    settings = @{
        mailEnabled = $true
        reminderEnabled = $true
        autoApplyDecisionsEnabled = $true
    }
    instanceEnumerationScope = @{
        "@odata.type" = "#microsoft.graph.accessReviewQueryScope"
        query = "/servicePrincipals/{app-id}/appRoleAssignedTo"
    }
}

# Create the review
New-MgIdentityGovernanceAccessReviewDefinition -BodyParameter $params

Explanation of the Code:

• displayName and description: These help you track the review in your admin portal.
• autoApplyDecisionsEnabled: This is set to true to ensure that when a reviewer clicks "Deny," the user is automatically removed from the assignment.
• query: This points the review to the specific application role assignments, ensuring that only the relevant users are included in the audit.

Warning: Always test your automation scripts in a development or sandbox tenant before deploying them to your production environment. Incorrectly scoped API calls could inadvertently trigger massive access removals across your entire organization.

Industry Best Practices for Access Reviews

Implementing Access Reviews is not just a technical task; it is a change management process. Here are the industry-standard best practices to ensure your program is successful:

• Start Small: Don't try to review every single group and application on day one. Start with the most sensitive resources (e.g., Global Admin roles, Finance apps) and expand your scope as you become comfortable with the process.
• Communicate Clearly: Before launching a review, inform the managers and owners who will be doing the reviewing. Explain why this is important and provide them with clear instructions on how to perform the review.
• Monitor Completion Rates: Use the reporting dashboard to track how many reviews are being completed on time. If completion rates are low, it usually means your reviewers are overwhelmed or don't understand the process.
• Use Self-Reviews for Low-Risk Apps: For low-risk applications, you can allow users to perform a "self-review." This saves time for managers while still putting the onus on the user to justify their continued access.
• Integrate with SIEM: Export your Access Review logs to your SIEM (like Microsoft Sentinel) to correlate access removals with other security events. This helps you understand if access was removed as a result of a security investigation.

Common Pitfalls and How to Avoid Them

Even with the best intentions, organizations often hit roadblocks. Here are the most common mistakes:

1. Excessive "Review Fatigue"

If you send a manager 50 different review requests in a single month, they will likely just click "Approve" on everything to get rid of the notifications.

• Solution: Space out your reviews. Stagger the schedules so that managers are only reviewing a manageable number of items each month.

2. Lack of Actionable Data

If a reviewer doesn't know who a user is or why they have access, they won't know whether to approve or deny.

• Solution: Use the "Reviewer Decision Helper." Entra ID provides data such as "last sign-in date." If a user hasn't signed into an app for 90 days, the system can highlight this to the reviewer, making it much easier to decide to deny access.

3. Ignoring the "Deny" Workflow

Some organizations set up reviews but fail to configure what happens when a reviewer denies access.

• Solution: Always enable "Auto-apply" or ensure your IT team has a manual process to follow up on "Deny" decisions immediately. If a denial is not followed by a removal, the review is useless.

Quick Reference Table: Reviewer Types

Frequently Asked Questions (FAQ)

Q: Can I review access for users who are not in my Entra ID? A: No, Access Reviews are built specifically for identities managed within Microsoft Entra. For external systems, you would need to export data or use an identity governance platform that integrates with those specific systems.

Q: What happens if I don't select a fallback reviewer? A: If the assigned reviewer (e.g., the manager) is unavailable or doesn't respond, the system will not be able to complete the review. It is best practice to always assign a fallback reviewer or a group of administrators to ensure the process continues.

Q: Can I customize the email notifications for reviewers? A: While you cannot change the core structure of the email, you can customize the "Additional content for reviewer email" field in the review settings. This is a great place to provide links to internal documentation or contact information for questions.

Q: Does an Access Review remove the user from the organization? A: No, it only removes the user's access to the specific resource (group, application, or role) being reviewed. The user account remains active in your directory.

Key Takeaways

1. Identity is the Perimeter: In modern cloud environments, managing access is the most effective way to secure your infrastructure. Access Reviews are your primary tool for maintaining a "least privilege" environment.
2. Automation is Essential: Do not rely on manual spreadsheets. Use Entra ID's native Access Reviews to automate the lifecycle of permissions, from notification to revocation.
3. Context Matters: Use features like "last sign-in date" to provide reviewers with the context they need to make informed decisions. An informed reviewer is much more likely to make an accurate, secure choice.
4. Governance is a Cycle: An Access Review is not a one-time project. It must be a recurring process to account for the constant movement of employees and the evolution of job roles.
5. Balance Security and Productivity: If you make the review process too difficult, users will find ways to bypass it. Keep the process simple, provide clear instructions, and ensure that access is only removed when the business case for it is truly gone.
6. Accountability: Always ensure that every review has a clear owner. If a manager leaves the company, make sure your processes automatically update the review ownership so that security audits do not stall.
7. Audit and Improve: Use the data from your Access Reviews to identify patterns. If you notice specific applications are constantly being flagged for removal, perhaps your automated provisioning process for that app needs to be adjusted.

By following these principles and implementing a consistent Access Review strategy, you transform identity governance from a tedious compliance requirement into a powerful security asset that protects your organization from the inside out. Remember that security is not a static destination; it is a continuous process of verification, and Access Reviews are the heartbeat of that process.