SharePoint Security: A Complete Guide With Best Practices

SharePoint is one of the most powerful collaboration platforms in Microsoft 365. Teams use it to co-author documents, share information inside and outside the organization, and store business-critical data. 

Since it’s embedded in everyday work, however, SharePoint is often exposed to accidental data leaks, insider risk, and misconfigured access.

While Microsoft provides strong built-in security for SharePoint, most SharePoint incidents aren’t caused by exploited vulnerabilities (though sometimes they are). They usually happen when default settings aren’t adjusted, permissions are too broad, or sharing lacks proper controls.

This guide covers how to manage SharePoint Online security and its key best practices. Keep reading to learn how to control sharing, tighten permissions, and protect sensitive data across your SharePoint environment.

How Secure is SharePoint?

SharePoint Online is built on Microsoft’s enterprise-grade cloud infrastructure and benefits from the same security investments that protect Microsoft 365 and Azure as a whole. 

At a platform level, Microsoft handles physical security, service availability, encryption at rest and in transit, and baseline threat protection.

However, SharePoint security is only as strong as its configuration. Most data exposure incidents don’t occur because Microsoft’s platform was compromised but because external sharing was too open or permissions were assigned directly to users instead of groups.

How SharePoint Security Works

SharePoint security is built on several interconnected layers that determine who can access content, how they access it, and what actions they can perform.

Identity and Authentication

Every SharePoint access request starts with identity and authentication. SharePoint Online relies on Microsoft Entra ID (Azure AD) to authenticate users, including internal employees and external guests.

Authorization and Permissions

Once a user is authenticated, SharePoint evaluates what they’re allowed to do. This is handled through permissions, which determine whether a user can read, edit, share, or manage content.

Sharing and Collaboration Controls

Sharing settings define how content moves inside and outside your organization. 

These controls include:

• Tenant-wide external sharing settings.
• Site-level sharing options.
• Link types and expiration policies.

Managing SharePoint Online Security

Managing SharePoint security is a shared responsibility among Microsoft 365 admins, SharePoint admins, site owners, and compliance teams. Most security issues arise don’t occur because the platform is weak but because teams don’t change default settings, use overly broad permissions schemes, or have unclear ownership of security responsibilities. 

Now that you’ve got the basics, let’s examine how you can manage SharePoint Online security — which is an ongoing process that never ends.

Start with Tenant-Level Security Settings

Tenant-level settings define the outer security boundary for your entire SharePoint Online environment. These settings apply globally and should be reviewed before users begin actively collaborating or sharing data.

To adjust these settings, access the SharePoint Admin Center.

To begin:

1. Go to Microsoft 365 Admin Center and sign in to your work or school account.​​​​​​​

2. Navigate to Admin centers → SharePoint.

3. You are now in the SharePoint Admin Center, where all tenant-wide security and sharing policies are configured.

This is the first place administrators should check out when locking down SharePoint Online.

Configure Tenant-Level Sharing Policies

Uncontrolled sharing is one of the most common causes of SharePoint data exposure. By default, SharePoint may allow very permissive external sharing, including anonymous access links. 

To manage sharing settings, navigate to the SharePoint Admin Center, and go to Policies → Sharing.

Review the sharing slider for SharePoint and OneDrive.

This slider determines how content can be shared across your organization.

If your goal is keeping data safe, these settings must be intentionally configured.

Apply Advanced External Sharing Controls

Beyond the main sharing slider, SharePoint provides granular controls to reduce risk even further.

Restrict External Sharing by Domain

You can explicitly allow or block sharing with specific external domains. Here’s how:

1. Go to Policies → Sharing.
2. Scroll to More external sharing settings.

3. Enable Limit external sharing by domain.
4. Choose:

• Allow only specific domains (recommended for partners).
• Or Block specific domains.

This ensures users cannot accidentally share files with untrusted or personal email domains.

Control Access to SharePoint from Devices and Locations

SharePoint Online includes access controls that limit how and from where users can access content.

Configure Access Control Policies

To configure access controls:

1. Go to the SharePoint Admin Center.
2. Navigate to Policies → Access control

These controls are especially valuable for organizations with remote workers or bring your own device (BYOD) environments.

Manage Permission Inheritance Carefully

There are legitimate cases where specific libraries or documents require restricted access.

To break inheritance:

1. Navigate to the library or document.

2. Open Settings → Site Permissions.

3. Select Stop inheriting permissions from Permissions menu.

4. Remove default groups if necessary.

5. Add only the users or groups that need access to the shared document.

Use this approach sparingly. Excessive item-level permissions make environments difficult to audit and increase security risks.

Control How Users Share Content at the Site Level

SharePoint allows site owners to control who can share files, folders, and sites.

Configure Sharing Permissions for Site Members

From Site Settings → Site Permissions → Site Sharing settings, choose one of the following:

• Owners and members can share everything.
• Only owners can share the entire site.
• Only owners can share files, folders, and the site.

Organizations new to SharePoint or handling sensitive data often start with owner-only sharing and relax permissions over time as users become more security-aware.

SharePoint Security Best Practices

Effective SharePoint security requires a dual approach. 

First, you must secure SharePoint as an environment by tightening tenant-wide and site-level configurations that control access and sharing. Second, you need to secure the data stored within SharePoint by applying protections that follow the content wherever it goes.

Secure SharePoint as an environment

Securing SharePoint as an environment focuses on controlling who can access SharePoint, how they can access it, and how sharing behaves by default. These controls form the foundation of your SharePoint security posture. 

Follow these best practices to secure your SharePoint.

1. Review and Tighten Tenant-Level Sharing Settings

Tenant-level sharing settings act as the first security gate for SharePoint Online. They define the maximum level of sharing allowed across SharePoint Online. 

Leaving these settings at their defaults is one of the most common causes of data exposure.

How to implement

1. Open the SharePoint Admin Center.
2. Navigate to Policies → Sharing.
3. Review the external sharing slider for SharePoint and OneDrive.

Best practice

• Avoid anonymous “Anyone” links whenever possible.
• Prefer sharing with authenticated external guests.
• Align OneDrive sharing with SharePoint sharing to avoid loopholes.

2. Restrict External Sharing by Domain and Security Group

Not all external collaboration carries the same level of risk. SharePoint allows you to control who can share and with whom.

How to implement

• Configure allowed or blocked external domains.
• Limit external sharing privileges to a dedicated security group.
• Require expiration on external sharing links.

3. Control Access From Unmanaged Devices and Locations

Accessing SharePoint from unmanaged or insecure devices significantly increases risk.

How to implement

1. Open SharePoint Admin Center.
2. Go to Policies → Access control

3. Configure:
   • Restrictions for unmanaged devices.
   • Automatic sign-out after inactivity.
   • Allowed network locations.
   • App-based access limitations.

4. Use SharePoint Groups Instead of Individual Permissions

Managing permissions at the user level quickly becomes unmanageable and risky.

Best practice

• Use SharePoint’s default groups (Owners, Members, Visitors).

• Add Microsoft 365 or Entra ID security groups to SharePoint groups.
• Avoid assigning permissions directly to individual users.

Secure the Data Stored Within SharePoint

Once the environment is locked down, the next priority is protecting the data itself. These best practices focus on preventing unauthorized access, accidental exposure, deletion, and data exfiltration.

5. Protect Sensitive Documents with Structured Access

Sensitive content should not live in general-purpose libraries.

Best practice

• Store sensitive files in dedicated libraries.
• Restrict access using SharePoint groups.
• Enable content approval for sensitive libraries and lists.

6. Reevaluate Default “People in Your Organization” Links

Organization-wide sharing links can expose content more broadly than intended.

Best practice

• Assess whether organization-wide links are appropriate per use case.

• Use more restrictive link types for confidential content.

• Encourage intentional link selection during sharing.

7. Apply Sensitivity Labels and Data Loss Prevention (DLP)

Permissions alone are not enough to protect sensitive information.

Best practice

• Apply Microsoft 365 sensitivity labels to SharePoint files.
• Use encryption, watermarks, headers, and footers.
• Deploy DLP policies to detect and restrict sensitive data sharing.

8. Prepare for Ransomware and Malicious Activity

Cloud platforms are not immune to ransomware-related incidents.

Best practice

• Monitor for unusual file activity or mass changes.
• Immediately stop sync activity if ransomware is suspected.
• Be prepared to restore affected content quickly.

Wrapping Up: How Spin.AI Strengthens SharePoint Security

Even with a strong configuration, SharePoint data can still be lost due to user error, ransomware, or malicious activity. Native recycle bins and retention policies have limitations and are not designed for fast, granular recovery.

If you’re looking to lock down your SharePoint environment, Spin.AI can help.

Spin.ai provides an additional layer of protection with automated backup, rapid recovery, and security insights for your entire Microsoft 365 ecosystem, including SharePoint Online.→ Get started with Spin.ai’s Microsoft 365 Backup & Recovery solution today and strengthen your SharePoint security.

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