CISA.MS.SHAREPOINT.1.3: External sharing SHALL be restricted to approved external domains and/or users in approved security groups per interagency collaboration needs.

Not run by Mito today

This check needs a connection to SharePoint Online PowerShell, which Mito’s assessment does not set up. Mito reports it as skipped.

ID	CISA.MS.SHAREPOINT.1.3
Severity	High
Suite	CISA SCuBA baselines
Product	SharePoint
Feature	External sharing
Security area	External access and sharing
Resource type	Tenant
User impact of fixing	Medium
Effort to fix	Medium
Benchmark	CISA SCuBA Secure Configuration Baselines for Microsoft 365 ScubaGear main, 2026-10-11, MS.SHAREPOINT.1.3 (SHALL)
Framework controls	cisa-scuba:MS.SHAREPOINT.1.3 nist-800-53-r5:AC-3 Access Enforcement nist-800-53-r5:AC-6(10) Least Privilege | Prohibit Non-privileged Users from Executing Privileged Functions
MITRE ATT&CK	T1048, T1213.002, T1530
Reads from	SharePoint Online PowerShell

What this checks and how to fix it

External sharing SHALL be restricted to approved external domains and/or users in approved security groups per interagency collaboration needs.

Rationale: By limiting sharing to domains or approved security groups used for interagency collaboration purposes, administrators help prevent sharing with unknown organizations and individuals.

Remediation action:

This policy is only applicable if the external sharing slider on the admin page is set to any value other than Only People in your organization.

1. Sign in to the SharePoint admin center.
2. Select Policies > Sharing.
3. Expand More external sharing settings.
4. Select Limit external sharing by domain.
5. Select Add domains.
6. Add each approved external domain users are allowed to share files with.
7. Select Manage security groups
8. Add each approved security group. Members of these groups will be allowed to share files externally.
9. Select Save.

Related links

• CISA 1 External Sharing - MS.SHAREPOINT.1.3v1
• CISA ScubaGear Rego Reference

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Mito check, based on CISA ScubaGear. Author: soulemike; contributors: SamErde. Open-source licences.