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Introduction:
In the modern collaborative enterprise, Microsoft 365 tenants often become inundated with external guest accounts. While essential for business operations, these accounts frequently outlive their usefulness, transforming from productivity tools into significant security liabilities. Proactive identity governance through tools like Entra ID Access Reviews is no longer a best practice but a critical necessity for maintaining a secure and compliant cloud environment.
Learning Objectives:
- Understand the security risks associated with unmanaged and inactive guest accounts in Entra ID.
- Learn how to configure and deploy both single-stage and multi-stage Access Reviews for automated guest user lifecycle management.
- Gain practical knowledge through step-by-step guides using both the Entra Admin Center and PowerShell for automation and reporting.
You Should Know:
1. The Hidden Dangers of Guest Account Sprawl
Inactive guest accounts are not merely digital clutter; they represent a tangible expansion of your organization’s attack surface. These orphaned accounts, often belonging to former vendors, consultants, or short-term collaborators, can be compromised through credential stuffing or phishing attacks. Once compromised, they can be used for lateral movement, data exfiltration, or as a foothold for more advanced attacks, all while flying under the radar of typical user monitoring.
- Configuring a Single-Stage Access Review in the Entra Admin Center
A single-stage review is the most straightforward method to automate the cleanup process. It automatically removes users who do not respond to a re-authentication prompt.
Step-by-step guide:
- Navigate to the Azure Portal > Azure Active Directory > Identity Governance > Access Reviews.
- Click New access review to create a new policy.
- In the “Select what to review” section, choose Teams + Groups or Applications. For a broad guest cleanup, select “Teams + Groups” and choose all relevant Microsoft 365 Groups or Teams.
- Under “Scope”, select Guest users only. This is crucial to ensure member accounts are not affected.
- In the “Specify reviewers” section, you can select specific users or, for automation, choose Guest users review their own access. This forces guests to attest to their own continued need for access.
- Under “Advanced settings,” configure the duration and recurrence. Set a recurrence (e.g., monthly or quarterly) to make this a continuous process.
- Enable the Auto apply results setting. This ensures that guests who fail to respond are automatically removed from the resources.
- Create the review. It will now run automatically based on your schedule, sending emails to guests and cleaning up inactive accounts without manual intervention.
3. Implementing a Multi-Stage Review for Critical Resources
For highly sensitive data or resources, a multi-stage review adds a layer of managerial oversight before any account is removed, providing an extra validation step.
Step-by-step guide:
1. Follow steps 1-5 from the single-stage guide.
- Instead of enabling “Auto apply results,” leave it disabled for the first stage. This creates a recommendation stage.
- After creating the first review, create a subsequent review for the same set of groups/resources.
- For this second review, select specific Manager or Selected reviewer(s) as the reviewer.
- The reviewers in this stage will see the results of the first stage (the guests’ self-attestation) and can make the final approval or denial, which will then be applied.
4. Automating Access Reviews with Microsoft Graph PowerShell
For large-scale deployments or integration into existing scripts, PowerShell provides a powerful automation interface.
Step-by-step guide:
1. Install the Microsoft Graph PowerShell module:
Install-Module Microsoft.Graph -Scope CurrentUser
2. Connect to Graph with the necessary scopes:
Connect-MgGraph -Scopes "AccessReview.ReadWrite.All", "Group.ReadWrite.All"
3. Use the following script as a template to create a new access review for a specific group’s guest members:
Import the module
Import-Module Microsoft.Graph.IdentityGovernance
Define parameters
$params = @{
displayName = "Quarterly Guest User Review for Marketing Team"
description = "Automated review of guest users in the Marketing Team group"
scope = @{
query = "/groups/<Your-Group-ID-here>/members"
queryType = "MicrosoftGraph"
}
reviewers = @(
@{
query = "./members/microsoft.graph.user/?`$filter=userType eq 'guest'"
queryType = "MicrosoftGraph"
}
)
settings = @{
mailNotificationsEnabled = $true
reminderNotificationsEnabled = $true
justificationRequiredOnApproval = $true
autoApplyDecisionsEnabled = $true Enables auto-removal
decisionHistoriesForReviewersEnabled = $true
}
recurrence = @{
pattern = @{
type = "absoluteMonthly"
interval = 3 Runs every 3 months
}
range = @{
type = "noEnd"
startDate = Get-Date -Format "yyyy-MM-dd"
}
}
}
Create the access review
New-MgIdentityGovernanceAccessReviewDefinition -BodyParameter $params
Replace `
5. Monitoring and Reporting on Access Review Findings
Creating the review is only half the battle. Continuous monitoring is essential to measure its effectiveness and demonstrate compliance.
Step-by-step guide:
- Within Identity Governance > Access Reviews, select a completed review.
- Click on Results to see a detailed breakdown of which guests were approved, denied, or did not respond.
- For advanced reporting, use PowerShell to export this data:
Get all access review definitions $definitions = Get-MgIdentityGovernanceAccessReviewDefinition -Filter "displayName eq 'Your-Review-Name'" Get the instances of that definition $instances = Get-MgIdentityGovernanceAccessReviewDefinitionInstance -AccessReviewScheduleDefinitionId $definitions.Id Get the decisions for a specific instance $decisions = Get-MgIdentityGovernanceAccessReviewDefinitionInstanceDecision -AccessReviewScheduleDefinitionId $definitions.Id -AccessReviewInstanceId $instances.Id $decisions | Select-Object ResourceDisplayName, Decision, ReviewedBy, ReviewedDateTime | Export-Csv -Path "AccessReviewResults.csv" -NoTypeInformation
- Use this data to track trends in guest account usage, identify departments with high guest sprawl, and provide evidence for audit purposes.
What Undercode Say:
- Inactive identities are low-hanging fruit for attackers. Automated de-provisioning is not an IT convenience; it is a foundational security control.
- The principle of least privilege must be applied dynamically. Access that is not continuously validated and reaffirmed becomes a standing privilege, which is a core vulnerability in any identity-centric security model.
The shift-left security philosophy must be applied to identity governance. Waiting for an audit finding or a security incident to clean up guest accounts is a reactive and risky posture. By implementing automated Access Reviews, organizations move from a static, perimeter-based defense to a dynamic, identity-aware security posture. This process continuously validates the “need-to-know” principle, drastically reducing the attack surface available to threat actors. The administrative overhead is minimal compared to the potential cost of a breach originating from a forgotten, compromised guest account.
Prediction:
The convergence of AI-driven identity analytics and automated governance will redefine cloud security. In the near future, we predict that Entra ID Access Reviews will evolve from a scheduled task into a real-time, behavior-based system. Using machine learning, it will automatically flag anomalous guest account activity for immediate review, seamlessly integrate with SaaS Security Posture Management (SSPM) tools for cross-platform policy enforcement, and move access certification from a quarterly chore to a continuous, intelligent process. Organizations that fail to adopt these proactive, automated identity hygiene practices will find themselves disproportionately targeted in the evolving landscape of cloud-based cyber threats.
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IT/Security Reporter URL:
Reported By: Pavithra Pavee – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
