Restrict Guest Access to Allowlisted Domains for Government & Public Sector
How government & public sector organizations should implement EXT-03 for Microsoft 365 security and compliance.
For government & public sector companies using Microsoft 365, restrict guest access to allowlisted domains is a security priority. This guide explains how EXT-03 helps government & public sector organizations protect their identity infrastructure while meeting industry-specific compliance mandates.
Why Government & Public Sector Organizations Need This Control
Government & Public Sector organizations face specific regulatory requirements including fedramp, nist-800-53, cis. The EXT-03 control helps address these requirements by:
- 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
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.
Industry-Specific Considerations
When implementing EXT-03 in a government & public sector environment, consider:
- **Regulatory requirements**: fedramp, nist-800-53, cis may mandate specific configurations
- **Risk tolerance**: Government & Public Sector organizations typically have moderate to low risk tolerance
- **Audit frequency**: Plan for regular compliance reviews
- **Documentation**: Maintain detailed records for regulatory inspections
How to Configure
EXT-03 requires the following 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
Configures cross-tenant access policy to block B2B direct connect by default. Partner allowlisting requires manual configuration.
With TrueConfig, you can implement this control automatically using our one-click remediation feature.
Government Compliance Requirements
Government organizations must comply with these frameworks, all of which address restrict guest access to allowlisted domains:
Why This Control Matters for Government
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.
Common threats in government & public sector:
- • Nation-state espionage campaigns
- • Ransomware targeting critical services
- • Insider threats from privileged users
For government & public sector organizations, EXT-03 is a key component of a compliant Microsoft 365 security posture. TrueConfig helps you implement and maintain this control while meeting industry-specific requirements.
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