The CISO’s guide to Microsoft 365 security: your immediate actions to avoid hidden risks before it’s too late

During the pandemic, organisations had no choice but to rapidly shift to cloud services like Microsoft 365 to maintain operational continuity. Now, as businesses rely more on these platforms, the security risks and hidden vulnerabilities from these rushed migrations are surfacing. CISOs are realising that default settings and hasty configurations have left their organisations exposed to advanced cyber threats. It’s time to address these risks before threat actors exploit your unseen vulnerabilities.

The good news is that security reviews don’t only identify risks; they also unveil unexpected benefits. In every assessment we conduct, we discover multiple useful capabilities that are available but unused. This, combined with the security benefits of identifying and closing vulnerabilities, provides a return on investment (ROI) that often greatly exceeds the cost of the assessment. This dual benefit of enhanced security and improved ROI makes a compelling case for regular security audits.

Cloud and the new threat landscape

The shift from on-premises infrastructure to cloud services has fundamentally altered the security landscape. For example, data isn’t protected the way it used to be behind corporate firewalls; it’s now available via the internet. This increased accessibility, while beneficial for productivity, also expands the attack surface and requires a complete overhaul of security strategies.

One of the primary issues stemming from rapid cloud adoption is the misconfiguration of security settings. In the rush to get systems up and running, many IT teams relied on default configurations provided by Microsoft, assuming they would be sufficient to protect their organisation’s data. Unfortunately, these default settings are often not optimised for an organisation’s specific security needs, leaving gaps that cybercriminals eagerly exploit.

A stark example of this is the misconfiguration of multifactor authentication (MFA) policies. We’ve seen a case where an organisation inadvertently set up its MFA policies in reverse, authorising users from non-approved countries to log in without MFA, while enforcing it for approved locations. Such errors, which can easily go unnoticed in a rapid deployment, negate the security benefits of MFA and leave the organisation vulnerable to unauthorised access.

The complexity of Microsoft 365’s security features further compounds these challenges. There are tens of thousands of settings, and no human can manually review them all. That’s why we’ve developed specialised tools to assess these environments effectively. These tools help organisations review everything IT teams have implemented over the past three years, identifying misconfigurations, unused features, and potential vulnerabilities that may have been overlooked during the initial migration.

Assess, uplift, and support

The process of securing a Microsoft 365 environment typically follows a cycle of assessment, uplift, and continuous support. This helps organisations identify and address immediate security concerns while maintaining a robust security posture over time

CISOs can mitigate cloud security risks in their Microsoft 365 environment immediately by:

• Performing a comprehensive security assessment: identify misconfigurations and vulnerabilities that have gone unnoticed.
• Prioritising critical fixes: focus on high-impact misconfigurations, like MFA setup or access permissions, that have immediate security consequences.
• Leveraging automated security tools: use specialised tools to continuously monitor and correct configuration drift.
• Maintaining continuous security support: adopt a long-term strategy that includes ongoing security reviews, updates, and human oversight to complement automated systems.

Advanced technologies introduce new threats, which is why it’s also important not to overlook fundamental security measures. We can’t forget the basics. Recent events have reminded us that software bugs are still among the most prominent threats in IT. This emphasis on basics extends to practical considerations often overlooked in digital-centric planning. For instance, having a 100-page incident response manual is great, but if it’s inaccessible during an outage, it’s worthless.

More importantly, as organisations continue to evolve their cloud strategies, new considerations emerge. This means that assessments must keep pace with new features and capabilities introduced by Microsoft. For example, we now assess Copilot configurations as part of our security reviews.

Businesses can mitigate the risks of moving to the cloud too quickly and secure their operations with the correct controls by adopting a proactive approach to security, which includes regular assessments, continuous improvement, and balancing advanced tools with human expertise. Attackers are also constantly testing defences, and configuration drift can quickly open unseen vulnerabilities. Regular assessments and uplifts protect an organisation’s digital assets.

Partnering with Fujitsu Cyber provides the expertise, tools, and support you need to navigate the complex landscape of modern cybersecurity threats and incident response.

Schedule a one-hour consultation with our cybersecurity experts today and take the first step towards securing your Microsoft 365 environment against hidden threats.