Microsoft 365 guide
Understanding External Sharing Security in Microsoft 365
A comprehensive checklist to secure external sharing across SharePoint, OneDrive, and Teams while maintaining collaboration efficiency.
By Spreeze team · Published · 2 min read
The Challenge of External Sharing
As organisations increasingly rely on Microsoft 365 for collaboration, external sharing has become both a necessity and a security concern. Whether you're working with clients, partners, or contractors, you need to ensure that sensitive information remains protected while enabling seamless collaboration.
Key Security Considerations
When implementing external sharing in Microsoft 365, there are several critical security layers to consider:
1. Tenant-Level Controls
Start by defining your organisation's external sharing policy at the tenant level. This establishes the baseline security posture for all SharePoint sites, OneDrive accounts, and Teams workspaces. Consider whether you need to allow sharing with anyone, only with authenticated external users, or only with specific domains.
2. Site and Document Level Permissions
Even with tenant-level controls in place, you can apply more restrictive settings at the site or document level. This granular approach ensures that highly sensitive content receives additional protection beyond your standard baseline.
3. Expiration and Access Reviews
Implement automatic expiration dates for external sharing links and conduct regular access reviews. This helps prevent the accumulation of outdated permissions that create security vulnerabilities over time.
Best Practices for Secure External Sharing
- Use sensitivity labels to automatically apply sharing restrictions to sensitive documents
- Enable Microsoft Entra ID (formerly Azure AD) B2B for better control over external user identities
- Implement conditional access policies that require multi-factor authentication for external users
- Monitor sharing activity through the Microsoft 365 compliance center
- Train users on secure sharing practices and the risks of oversharing
Conclusion
External sharing in Microsoft 365 doesn't have to be a security risk. With the right configuration, policies, and user training, you can enable secure collaboration with external partners while protecting your organisation's sensitive information.