Neither SharePoint Online nor on-premises SharePoint is inherently more secure. Online shifts protection and maintenance of the service infrastructure to Microsoft, while your organization remains responsible for tenant identity, sharing, access and data-governance settings. On premises gives you more direct control over the infrastructure and data location, but also makes you responsible for operating and securing the farm. Hybrid adds a connection and trust boundary between the two.
How the security responsibilities differ
| Deployment | Who operates the service infrastructure? | What the organization must secure |
|---|---|---|
| SharePoint Online | Microsoft operates and protects the Microsoft 365 service infrastructure. | The organization configures and governs tenant identity, access, sharing, devices, data protection and monitoring. |
| SharePoint Server on premises | The organization operates the SharePoint farm and its supporting environment. | The organization secures and maintains the servers, databases, network boundaries, SharePoint configuration, access and integrations. |
| Hybrid | Microsoft operates the cloud service; the organization operates its on-premises farm and the connection between them. | Both sides need appropriate controls, with additional attention to identities, trust, certificates, endpoints and cross-environment access. |
That division matters more than the labels “cloud” and “on premises.” Microsoft’s SharePoint deployment diagrams illustrate different deployment architectures, but an architecture alone does not establish that a particular environment is secure.
What security risks and protections apply to SharePoint Online?
Microsoft describes SharePoint and OneDrive data as protected in transit and at rest, with authenticated access redirected to HTTPS. It also describes service-side operational controls, including multifactor authentication for engineering administration and just-in-time rather than standing engineer access. These are Microsoft-described service protections; they do not mean a customer tenant is automatically configured to limit access appropriately. See Microsoft’s cloud data security measures for SharePoint and OneDrive.
Risks the customer still needs to manage
Common exposure risks arise from tenant configuration and content access: overly broad sharing, weak identity protections, access from unmanaged devices, inappropriate permissions, or inadequate monitoring. These are practical consequences of the customer controls Microsoft recommends, not a published comparison of breach rates between cloud and on-premises deployments.
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Tenant controls to plan and review
- Identity: Require multifactor authentication and review sign-in protections.
- Devices and sessions: Consider device-based Conditional Access to restrict unmanaged devices, alongside session controls appropriate to your requirements.
- External sharing: Set sharing policies deliberately and review who can share content with people outside the organization.
- Data protection: Use data loss prevention policies where appropriate, and verify that the required features are available under your licensing and configuration.
- Monitoring: Plan how to review activity through the Management Activity API or Cloud App Security, investigate suspicious sign-ins with Entra ID Protection, and use Secure Score to assess the tenant against a baseline. Feature availability and licensing vary, so confirm entitlements before relying on a control.
What must an organization secure with SharePoint Server on premises?
With an on-premises deployment, the organization operates the SharePoint farm, database environment and surrounding network. That means it must protect the servers and their roles, control service and port configuration, maintain firewall boundaries, and manage updates and day-to-day operations. Microsoft’s SharePoint Server security hardening guidance is role-specific and calls for a firewall between farm servers and outside requests.
Where operational risk can arise
- A farm exposed to outside requests or insufficiently segmented from other systems.
- Unpatched or unsupported software, including server components and dependencies.
- Overly broad administrative access or weak operational procedures.
- Integrations that create additional communication paths to file shares, SQL Server, web services or other external data sources.
- Gaps in monitoring, backup and recovery, or incident response.
These are risks implied by the responsibilities and hardening requirements of operating a farm; Microsoft’s cited guidance does not rank on-premises SharePoint against SharePoint Online by incident rate. Greater control over infrastructure and location can be useful, but it delivers a security benefit only when the organization can maintain that environment competently.
When data-location requirements may matter
Some organizations select on-premises SharePoint or OneDrive because industry restrictions or internal rules limit transmitting data over the internet. Microsoft discusses these considerations in its planning guidance for OneDrive in Microsoft 365 or SharePoint Server. A local deployment does not, by itself, prove compliance or make data safer; validate the actual legal, regulatory and contractual requirements that apply to the content.
What extra security considerations does hybrid SharePoint add?
Hybrid SharePoint connects a Microsoft 365 tenant to an on-premises web application; it is not simply two separate systems with no shared trust. Microsoft’s hybrid connectivity guidance describes cloud-originated requests passing through a reverse proxy to a designated on-premises web application and calls for planning certificates and authentication.
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Trust, identity and connection points
Hybrid configurations can involve synchronized or federated user accounts and server-to-server trust between SharePoint Server and Microsoft 365. The accounts guidance for hybrid configuration and testing describes accounts and trust used to enable access across environments. The Hybrid Configuration Wizard creates a server-to-server/OAuth connection.
Each integration brings configuration that must be owned and reviewed: credentials and privileges, exposed endpoints, certificates and renewals, permissions, and monitoring. This is an architectural expansion of the trust boundary, not evidence of a measured increase in breach rates.
Limit privileged setup and test access
The wizard requires privileged roles, but Microsoft recommends using the least-privileged roles possible and reserving Global Administrator use for emergency cases when an existing role cannot be used. As part of setup and ongoing operations, assign owners for certificate renewal and endpoint exposure, review account privileges, and test that permitted users can access the required resources while disallowed users cannot.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Does SharePoint Server version support change the security decision?
Yes. Product support affects the maintenance and security calculus for any on-premises farm. Microsoft’s US Lifecycle listing gives SharePoint Server 2019 an extended-support end date of July 15, 2026, while Microsoft’s upgrade overview states July 14, 2026. The sources differ by one day; both dates have passed as of October 4, 2026. Check the current SharePoint Server 2019 Lifecycle record for the date applicable to operational decisions, and do not assume an installed 2019 farm receives ordinary product support after the listed end date.
Microsoft lists SharePoint Server Subscription Edition as “In Support” under the Modern Lifecycle Policy, with no retirement date shown in the accessed listing. That status is not a substitute for installing supported updates, securing Windows Server and SQL dependencies, and following current servicing guidance.
How to choose a deployment model for your security needs
| Decision area | Questions to answer | Security implication |
|---|---|---|
| Data location and transfer | Must particular content remain in a controlled environment? Are internet transfers restricted? | Requirements may constrain cloud or hybrid designs; validate the actual rules and the content they cover. |
| Control and responsibility | Which infrastructure, identity, access and data controls must your organization operate directly? | Online shifts service-layer operations to Microsoft but still requires tenant governance. On premises adds farm and infrastructure duties. |
| Operating capability | Can your staff and processes handle farm patching, network protection, backup and recovery, monitoring and incident response? | Direct control over a farm is useful only if it can be maintained securely. |
| Identity and sharing | How will you govern multifactor authentication, Conditional Access, external users, device restrictions and permissions? | Online controls require deliberate tenant configuration; hybrid identity must work securely across both environments. |
| Hybrid connectivity | Which endpoints, certificates, reverse proxies and trust relationships are required? | Every connection needs an owner, narrow exposure, credential governance, monitoring and renewal. |
| Version and servicing | Which exact SharePoint Server version and build are deployed, and are they supported? | Unsupported versions change the maintenance and migration calculus. Check the lifecycle record for the installed product. |
There is no universal winner in the available Microsoft guidance. Choose based on the data-location rules you actually need to meet, the controls your organization must manage itself, its ability to operate a farm, its identity and integration requirements, and the support status of its exact SharePoint Server version.
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