Hardening Microsoft 365: Stay Tuned to Your Risk Appetite

Microsoft 365 is a powerful, multifunctional platform — but its complexity can pose real challenges for IT risk and security managers tasked with maintaining a resilient security posture.

Default configurations seem convenient, but they're frequently a security risk. An example is BingBang, a security misconfiguration found in Microsoft's Azure Active Directory identity management system, affecting up to 25% of multi-tenant Azure applications.

More importantly, with continuous updates, patches, tweaks, and IT changes, your Microsoft environment can become a complex surface area that must be hardened continually to stay resilient against evolving threats.

Gartner suggests 99% of security breaches result from misconfiguration errors, even when tools are in place. And, acccording to Vectra AI, 71% of Microsoft 365 tenants have experienced at least one account takeover, averaging seven incidents per year per tenant.

The Reality of Hardening M365

IT and security teams often face these core challenges when locking down Microsoft 365 environments:

• Configuration drift: As permissions, policies, and features change, security configurations can slip out of alignment with an organisation’s risk posture.
• Lack of visibility: It's difficult to know whether your controls across workloads (Exchange, OneDrive, SharePoint, etc.) are working as intended.
• Time constraints: Teams are stretched thin between BAU demands and ongoing security initiatives. Reviewing every config, setting, and user entitlement manually? Unrealistic.
• Misaligned policies: Default settings may not reflect what’s ideal for your specific risk profile—or compliance requirements.

Why Configuration Matters

A misconfigured tenant isn’t just a weak link—it can become an attacker’s launchpad. With threat actors increasingly targeting identity and access vectors, getting granular with configurations is no longer optional.

To proactively manage risk and support resilience across Microsoft 365, I recommend security managers should zero in on these areas:

How to assess your Microsoft environment

Microsoft Secure Score is a security analytics tool within Microsoft 365 that assesses and scores an organisation's security posture. It provides a numerical score, ranging from 0 to 100%, indicating how well an organisation is implementing recommended security controls. A higher score signifies a stronger security posture and a lower risk of security breaches. 

In my experience, many organisations still have a significant gap to reach my recommended minimum threshold of 80%. And of note, it’s only a point-in-time assessment. Enforcement controls switched off as applications are upgraded, systems built or unique use-cases enacted can affect your posture thereafter.

Tuning Security to Your Risk Appetite

Aligning your Microsoft 365 setup with your security and compliance goals requires ongoing vigilance. To validate the effectiveness of your configuration strategy:

• Establish a baseline security posture aligned to your risk appetite.
• Measure current configurations against this baseline regularly.
• Set automated alerts for deviations and track remediation progress.
• Incorporate compliance mapping to standards like ISO 27001, PCI DSS, and ISM.

How can Vectra help?

Our Microsoft 365 Hardening & Compliance Service ensures your Microsoft 365 environment is continuously aligned with industry best practices such as CIS Benchmarks, Essential 8, NIST, and ISO 27001 — fully managed by our Network Operations Team.

The service integrates directly with Microsoft Graph APIs and Azure AD to collect configuration data across key services such as Exchange Online, Teams, SharePoint, and OneDrive. It continuously evaluates tenant settings against selected benchmarks or controls (e.g., CIS, NIST, ISO 27001), detects configuration drift, and automatically remediates deviations based on predefined policies.

All actions and alerts are logged and monitored through our NOC. Clients are then advised of any risks relating to the alert which may have been triggered by a change, that has affected the policy in place. Monthly compliance reports and change summaries are delivered to clients. This ensures an always-secure, always-auditable Microsoft 365 environment without manual overhead.

The outcome? A secure modern workplace monitored with least manual effort, to deliver maximum risk management. If you’re interested in how this works for your organisation, reach out for a demo.

We can help gain visibility into your security posture within minutes and get your tenancy aligned just as quickly. A current snapshot can be viewed within minutes, not days or weeks.

The Bigger Win: Operational Confidence

Empowering your IT staff with automated insights means less time manually chasing misconfigurations and more time focusing on strategic security initiatives. It also helps bridge the gap between security and operations—creating shared visibility across teams.

Hardening isn't a one-and-done. With Microsoft 365 constantly evolving, your defenses should too. Make sure your configurations move in lockstep with your risk strategy.