How to Fix: Restrict Guest Access to Allowlisted Domains
Step-by-step guide to implement restrict guest access to allowlisted domains in your Microsoft 365 environment.
5-10 minutes
Estimated Time
4
Steps
high
Severity
Maximum Security
Baseline Level
Why This Matters
At Level 3, external collaboration is tightly controlled. Only pre-approved partner organizations can access your tenant. This prevents social engineering and limits data exposure to vetted third parties.
Prerequisites
- 1Global Administrator or appropriate admin role in Microsoft Entra ID
- 2Access to Microsoft Entra admin center (entra.microsoft.com)
- 3Microsoft Entra ID P1 or higher license
Expected Configuration
- Guest invitations are restricted to an allowlist of trusted domains
- Cross-tenant access policies block all other external tenants
- External sharing in SharePoint/OneDrive is restricted to allowed domains
Remediation Steps
Review Current Configuration
Assess your current configuration in Microsoft Entra admin center.
- •Navigate to the relevant section in Entra admin center
- •Document current settings
- •Compare against expected state
Plan Implementation
Determine the changes needed to meet the expected configuration.
- •Review expected configuration requirements
- •Identify affected users or resources
- •Plan rollout strategy
Implement Changes
Apply the necessary configuration changes.
- •Make required configuration updates
- •Apply to appropriate scope
- •Document changes made
Validate and Monitor
Verify the changes are working as expected.
- •Run TrueConfig scan to verify compliance
- •Test affected functionality
- •Set up ongoing monitoring
Auto-Remediation Available
TrueConfig can automatically fix this control for you. Enable auto-remediation to have this configuration applied and maintained automatically.
Learn about auto-remediationRelated Resources
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