Data Strategy Breakdown Series - Secure Collaboration (3)

Introduction

Welcome back to the Data Strategy Breakdown Series. If you're joining us for the first time, here’s Part 1 on building a smarter data strategy and Part 2 on basic security hygiene. In this installment, we’re zooming in on a problem that’s become way too common in modern cloud environments: over-sharing, under-securing, and mismanaging collaboration.

Yes, we’re talking about secure collaboration - the thin red line between productivity and a front-page data breach. Let's break it down the Microsoft way (plus a few real-world insights from me).

Table of Contents

Why secure collaboration matters now

Top 15 secure collaboration controls

Conclusion

Why secure collaboration matters now

Cloud collaboration tools are the backbone of hybrid work, but with flexibility comes exposure. The convenience of sharing documents with one click often overrides caution, leading to data leaks, shadow IT, and unwanted AI visibility (hello, Copilot).

Even internal collaboration isn’t automatically safe. Microsoft 365 features often assume a “productivity-first” stance – security has to be layered in deliberately. Worse, default settings often expose more than intended, especially in SharePoint, OneDrive, and Teams.

Enter: collaboration controls. They’re not glamorous, but they are foundational.

Top 15 secure collaboration controls

I do want to point out that this list is by no means exhaustive when it comes to secure collaboration. If I were to list every single tiny setting within an M365 tenant that could improve your organisation's security, we’d be here for ages, and I’d probably spend every evening writing about secure-by-default tenants that still aren’t as secure as we’d hope. Also, there are instances where I’ve deliberately left out certain solutions because I’ll be covering them in a future post - just a heads-up in case anyone comes at me in the comments or DMs! Additionally, I don’t aim to rewrite Microsoft’s official documentation here, though I know it can sometimes be tough to navigate amidst thousands of pages. As always, consider this my personal list of top recommendations - but for the most up-to-date advice, I highly recommend checking Microsoft’s documentation. And, before making any changes in your environment, be sure to review the potential repercussions and test in a safe environment before applying it to production.

Here’s how Microsoft proposes to handle secure collaboration, along with direct documentation links and my interpretation of what it actually means in practice.

1. Do not use public Microsoft 365 Groups

Public groups = visibility to all tenant members, plus potential data sprawl into Copilot’s indexed corpus.

• Fix: Convert all your public M365 groups into private ones and apply container-level sensitivity labels to enforce private access.

  Reference: Learn about container labels

  
  

There are many different ways of making a group private and applying a container label to it.

One of them is in the M365 admin centre:

Navigate to admin.microsoft.com > Teams & groups > Active teams & groups > click into a group > Settings (tab) > Change privacy to 'Public' & under 'Sensitivity label' settings, choose a label that's been published and is scoped to cover containers.

2. Use the most restrictive guest user access setting

By default, guests can enumerate users and groups – not ideal.

• Fix: Set Guest user access to most restrictive in Entra ID.

  Reference: Configure guest access

  

  
  

3. Restrict user ability to create security + M365 groups and SharePoint sites

Unmanaged group/site sprawl = governance chaos.

• Reference: Limit group creation

4. Block self-service Copilot plugins and integrated apps

Copilot extensibility = potential for shadow AI plugins.

• Reference: Manage app extensions for Copilot

5. Use “Specific People” as default sharing setting

This forces conscious data sharing decisions, not accidental org-wide leaks.

• Reference: Configure OneDrive/SharePoint default sharing link

6. Set expiration for anonymous links

Anonymous access needs a kill switch.

• Reference: Manage anonymous sharing expiration

7. Expire guest access to OneDrive/SharePoint after X days

Guests don’t get Copilot now, but this policy is futureproofing.

• Reference: Guest access expiration policies

8. Prevent guests from sharing content they don’t own

Guests should never be content distribution vectors.

• Reference: Disable guest sharing permissions

9. Use data access governance reports for SharePoint

Label usage + sharing tracking = visibility you need for audits.

• Reference: Enable access governance reports

  

  
  

10. Enforce reauthentication via verification codes

Reauthentication reduces session hijack risk, especially on shared links.

• Reference: Configure reauth for shared links

  

  
  

11. Idle session sign-out on unmanaged devices

People walk away from unlocked laptops. This mitigates that.

• Reference: Set idle timeout policies

12. Review SharePoint/OneDrive org-wide sharing policies

There’s no “one-size” here - balance collaboration and risk.

• Reference: Overview: sharing settings

13. Block communication from Teams trial tenants

Trial tenants are increasingly used for phishing. Block them.

• Reference: Restrict external access in Teams

14. Require CAPTCHA for anonymous meeting joiners

Prevents bots from snooping on meetings.

• Reference: Set Teams CAPTCHA setting

15. Restrict Power Platform cross-tenant data connections

Tenant isolation prevents silent exfiltration of sensitive data.

• Reference: Enable tenant isolation

Conclusion

When we talk about secure collaboration, we’re talking about intentional data control. This list is designed to make your Microsoft 365 environment less permissive, more predictable, and drastically harder to misuse - both by accident and design.

Security shouldn’t be the price of productivity. But in reality, security must be the framework of productivity - or your collaboration platform will become your weakest link.

If you're overwhelmed: start with five. Build into your deployment pipeline. Work with your governance, compliance, and security teams together. Secure collaboration is not just an IT problem - it’s a business survival issue.

🛡️ Got questions? Need help implementing any of these? Reach out, comment, or connect. Let’s make data collaboration safe - without slowing you down.

Other references:

• https://learn.microsoft.com/en-us/microsoft-365/solutions/groups-teams-access-governance?view=o365-worldwide

• https://learn.microsoft.com/en-us/microsoft-365/solutions/microsoft-365-limit-sharing?view=o365-worldwide

• https://learn.microsoft.com/en-us/microsoft-365/solutions/setup-secure-collaboration-with-teams?view=o365-worldwide

• https://learn.microsoft.com/en-us/microsoft-365/solutions/best-practices-anonymous-sharing?view=o365-worldwide

• https://learn.microsoft.com/en-us/microsoft-365/solutions/create-secure-guest-sharing-environment?view=o365-worldwide

• https://learn.microsoft.com/en-us/microsoft-365/solutions/share-limit-accidental-exposure?view=o365-worldwide

• https://learn.microsoft.com/en-us/entra/external-id/external-collaboration-settings-configure

• https://learn.microsoft.com/en-us/sharepoint/teams-connected-sites

• https://learn.microsoft.com/en-us/sharepoint/change-external-sharing-site

• https://learn.microsoft.com/en-us/microsoft-365/admin/manage/manage-copilot-agents-integrated-apps?view=o365-worldwide

• https://learn.microsoft.com/en-us/microsoft-365/solutions/manage-creation-of-groups?view=o365-worldwide https://learn.microsoft.com/en-us/purview/sensitivity-labels-teams-groups-sites

• https://learn.microsoft.com/en-us/entra/identity/users/users-restrict-guest-permissions