M365 Security Myths That Could Be Costing You

Microsoft 365 offers a comprehensive security stack, but pervasive myths can lull organisations into a false sense of safety. Countering these misconceptions raises awareness and prompts targeted reviews—without prescribing every configuration change.

Myth 1: “M365 Is Secure by Default”

Reality: Default Teams and SharePoint settings permit external sharing on new sites. Without proactive configuration, sensitive files can leak. Regularly review sharing reports in the Security & Compliance Centre and apply tenant-wide sharing restrictions where needed.

Myth 2: “Once MFA Is On, We’re Covered”

Reality: MFA is foundational, but must be paired with Conditional Access policies. For instance, block legacy authentication protocols (basic auth) to prevent bypass, and require device compliance for high-risk applications.

Myth 3: “Audit Logs Aren’t That Useful”

Reality: Unified audit logs provide critical forensic evidence—who accessed what, when and from where. If retention is set too low (default 90 days for some events), you may lack evidence for investigations. Extend audit log retention for key events (e.g. mailbox access, admin role changes).

Myth 4: “Secure Score Tells the Whole Story”

Reality: Secure Score offers prioritised recommendations, but organisational context matters. A high Secure Score doesn’t guarantee zero risk; it simply indicates best practices coverage. Use it as a guide, not a compliance certificate.

Raising Awareness Through Targeted Insights

Instead of step-by-step guides, share mini case studies:

• A financial services firm discovered an open Teams channel with client data because they’d never adjusted default sharing settings.

• An education provider saw reduced phishing success rates after blocking legacy auth and enforcing Conditional Access.

Prompt readers to ask themselves: “When was the last time we audited external sharing? Have we blocked basic auth in legacy protocols? Does our retention policy align with investigation needs?” These questions drive self-assessment without prescribing every technical command.