Hardening our digital defenses with Microsoft Baseline Security Mode

Security isn’t just a feature—it’s a foundation.

As threats grow more varied, widespread, and sophisticated, enterprises need to rethink how they protect their environments. That’s why we, in Microsoft Digital, the company’s IT organization, took a necessary step forward and deployed Microsoft Baseline Security Mode internally across the company.

Baseline Security Mode is a new approach to endpoint protection that enforces secure-by-default configurations across our enterprise. And it’s not just about locking things down—it’s about doing so in a way that’s scalable, manageable, and respectful of user experience.

This is a story for every organization trying to balance usability with security. Baseline Security Mode is designed to help IT teams enforce protections without breaking productivity. It’s a shift toward proactive defense with standardized secure settings.

Understanding the need for Microsoft Baseline Security Mode

Security must evolve with the environment.

At Microsoft Digital, we’ve built a strong foundation of endpoint protection over the years. But as our ecosystem expanded—more devices, more workloads, more diverse user needs—we saw an opportunity to take our security posture to the next level.

Our existing configurations were effective, but they reflected the natural complexity of a large enterprise. Different teams had different requirements. Some relied on legacy technologies that had served them well. Others needed flexibility to support specialized workflows. Over time, this led to variation in how security policies were applied.

We wanted to unify that approach.

Baseline Security Mode emerged as a way to streamline and strengthen our defenses. It was about building on what worked. We started by identifying areas where legacy protocols and configurations could be modernized. That included technologies like ActiveX controls and older authentication flows, which we carefully evaluated and phased out where appropriate.

We also improved how we gather and use telemetry. Initially, we had limited visibility into how certain features were used. That made it harder to predict the impact of changes. So, we ran pilots, collected feedback, and refined our approach. Baseline Security Mode was a game changer here, providing built-in reports that gave us the visibility we needed to observe the impact of applying settings in our environment. For example, when we reviewed blocking legacy file formats, we discovered that some workflows depended on them. We responded quickly, offering alternatives and guiding users through the transition.

Ease of use was a priority.

We built intuitive controls into the Microsoft 365 admin center, allowing IT admins to manage policies with just a few clicks. No more manual scripts. No more guesswork. We also introduced exception handling to support specialized needs, ensuring that security didn’t come at the cost of productivity.

We worked closely with internal stakeholders, including compliance teams and work councils, to validate every step and build trust. We made sure the experience was smooth, the tools were reliable, and the changes were clearly communicated.

This wasn’t just a technical upgrade—it was a cultural shift.

Baseline Security Mode gave us a way to unify our security posture while honoring the diversity of our environment. It’s a smarter, more scalable way to protect our endpoints, and it reflects everything we’ve learned from years of experience.

Putting consistent security configuration into practice

Baseline Security Mode establishes a new standard, enabling organizations to be secure by default.

It is the result of a collaborative effort of multiple product teams at Microsoft, building on their security and incident-handling expertise.  It’s designed to simplify and strengthen endpoint protection across Windows and Microsoft 365. The feature lives in the Microsoft 365 admin center, where IT admins can enforce modern security policies with just a few clicks.

“When we blocked certain file formats, users were confused by the error messages and thought they were blocked from saving the file. So, we ran pilots, gathered feedback, and helped the product team build an improved error experience to save blocked formats to safe, newer formats.”

Harshitha Digumarthi, senior product manager, Microsoft Digital

The product teams delivered 20 features across five workloads: Office, OneDrive and SharePoint, Teams, Substrate, and Identity. Each one targets a specific risk—blocking legacy authentication, disabling insecure protocols, restricting ActiveX, and more.

When we deployed Baseline Security Mode as Customer Zero at Microsoft Digital, our job was to validate these features and controls in real-world enterprise conditions.

We pushed for exception handling.

Some users still relied on legacy formats or protocols. Certain teams, for example, needed access to older Office features. So, we worked with the product team to ensure exceptions could be built into the UI.

That flexibility was key. We knew from experience that without it, customers might hesitate to adopt the feature.

“When we blocked certain file formats, users were confused by the error messages and thought they were blocked from saving the file,” says Harshitha Digumarthi, a senior product manager at Microsoft Digital. “So, we ran pilots, gathered feedback, and helped the product team build an improved error experience to save blocked formats to safe, newer formats.”

We also pushed for better telemetry.

“When we heard about Baseline Security Mode, it was still in ideation. There were no tools in the Microsoft 365 admin center yet. We had to figure out how to enable this internally while the product team built the capabilities in parallel.”

Markus Gonis, senior service engineer, Microsoft Digital

At first, we had only a few days of data. That wasn’t enough to understand how features were used or what impact they would have. So we worked with the product team to expand telemetry, improve error reporting, and reduce false positives, including identifying bugs that skewed metrics and made troubleshooting harder.

We ran the deployment through our Tenant Trust Program and work council reviews to ensure global compliance. That gave us—and our customers—confidence.

Baseline Security Mode isn’t just a feature. It’s a shift in how we think about security, and we’re proud to have helped shape it.

Deploying Baseline Security Mode at Microsoft Digital

Rolling out Baseline Security Mode wasn’t just a technical exercise—it was a cross-team effort that demanded precision, patience, and partnership.

Microsoft Digital took the lead on deployment. We acted as Customer Zero, testing every feature in real-world conditions before it reached customers. That meant working closely with the product team to validate functionality, identify bugs, and shape the user experience.

“When we heard about Baseline Security Mode, it was still in ideation,” Gonis says. “There were no tools in the Microsoft 365 admin center yet. We had to figure out how to enable this internally while the product team built the capabilities in parallel.”

Telemetry was limited. We had only 30 days of data to work with. That made it hard to predict how changes would affect users, so we ran pilots with internal user acceptance testing cohorts and we deployed in phases.

“It was a great Customer Zero experience. Our security teams stood to benefit from Baseline Security Mode features, and we helped the product team find bugs and the issues that just hadn’t come up in early testing or at a large scale. It was a win-win situation”

John Philpott, principal product manager at Microsoft Digital

For some legacy protocols, usage was low. In these cases, the features being deployed made removing these protocols seamless. Where usage was higher or unclear, a more detailed approach was required.

First, a few thousand users. Then 50,000. Then 100,000. Eventually, the entire Microsoft tenant. We paused between each wave to monitor help desk tickets, gather feedback, and confirm that our mitigation strategies were working.

Communication was critical.

We ran targeted campaigns, sent individual emails, and published technical reports explaining what was changing, why it mattered, and how users could adapt. We even used Viva Engage to notify users directly. It was important to explain to users why longstanding functionalities were being removed. We had to explain what we were doing and how to mitigate any impact.

We did a lot of work with the product team to ensure the user experience and the IT pro experience both exceeded expectations.

“It was a great Customer Zero experience,” says John Philpott, principal product manager within Microsoft Digital. “Our security teams stood to benefit from Baseline Security Mode features, and we helped the product team find bugs and the issues that just hadn’t come up in early testing or at a large scale. It was a win-win situation.”

We flagged inconsistencies in policy syntax, pushed for better error handling, and worked with the product team to align deployment tools across workloads.

But we didn’t stop at deployment. We tracked progress, validated telemetry, and signed off on each feature before it moved into broader rollout. We even helped pave the way for the next iterations, identifying features that needed more design work or deeper telemetry before they could be deployed.

This was a true partnership. The product team built the features. We tested them, validated them, and helped make them better.

Baseline Security Mode is now live across Microsoft. And it’s ready for the world.

Capturing real benefits

Baseline Security Mode is more than a set of policies—it’s a platform for proactive defense.

The product team built it to reduce legacy risks and enforce modern security standards across Microsoft 365 workloads. Microsoft Digital validated it in production, surfacing bugs, shaping telemetry, and confirming that the features worked as intended.

We tested 22 features across Office, OneDrive & SharePoint, Substrate, Identity, and Teams. Each one targeted a specific vulnerability—like blocking ActiveX controls, disabling Exchange Web Services, or enforcing phishing-resistant authentication for admins.

We flagged critical ActiveX dependencies in third-party apps —something the product group hadn’t found—which enabled them to initiate removal. That kind of early detection helped fix issues before the features reached customers.

We found regressions in PowerShell and legacy authentication flows. The OneDrive and SharePoint team caught a high-impact bug and worked with the product team to resolve it.

That validation mattered.

We also helped shape the admin experience.

Exception handling was built into the UI. Admins could create security groups, assign users, and manage exclusions directly in the Microsoft 365 admin center.

“There’s no need to handle everything manually,” Philpott says. “Simply click here and then here to disable. It’s a much simpler process.”

Extending benefits to Microsoft customers

Baseline Security Mode is ready for enterprise.

We’ve tested it. We’ve hardened it. And we’ve made it easier to adopt.

Microsoft Digital’s deployment journey helped shape the product into something customers can trust. We didn’t just validate features—we made sure they worked in real-world environments, across diverse teams, and under the pressure of scale.

 The product team designed the features to be enterprise-ready. We ran them through our Tenant Trust Program and work council reviews to ensure compliance across global regions. That gave us confidence—and gave customers confidence too.

The benefits are clear. We’ve reduced our attack surface. We’ve improved compliance. We’ve made it easier for IT teams to enforce security without disrupting workflows. And we’ve laid the groundwork for secure-by-default computing across Microsoft.

 Customers can do the same.

Start small. Run pilots. Monitor impact. Use the tools in the Microsoft 365 admin center to deploy policies, manage exceptions, and guide users through the change. And don’t be afraid to ask for help—our journey has shown that collaboration between deployment teams and product teams makes all the difference.

Baseline Security Mode is ready, and we’re ready to help others adopt it.

Looking ahead

The first wave of Baseline Security Mode—BSM 2025—delivered 22 features across five major workloads. Microsoft Digital helped validate and deploy those features across the enterprise. And the next wave of features is already in motion.

And it’s bigger, with 46 features, more than double what we had in the first round. The product team is expanding coverage to include deeper protocol restrictions, broader app controls, and more granular authentication policies.

We’re also preparing for broader industry adoption.  

Governments, regulators, and enterprise customers are asking for secure-by-default configurations. Baseline Security Mode is our answer. And the next version will make it even easier to adopt.

We’ll continue to lead as Customer Zero. We’ll test new features, validate insights surfaced by telemetry, and share feedback with the product team. We’ll run pilots, monitor impact, and guide users through the change. And we’ll keep pushing for simplicity, scalability, and trust.

Because security isn’t a one-time project— It’s a mindset, and it’s Microsoft’s highest priority.