Microsoft 365 security in Australia is failing at the configuration level — not the product level. According to the ASD’s Annual Cyber Threat Report 2024–25, the average cost of a cyber incident for an Australian medium-sized business is now $97,200, up 55% in a single year. In most cases, the attacker didn’t break through a firewall. They walked in through a misconfigured Microsoft 365 tenant.
Microsoft 365 is an extraordinarily capable platform. But it doesn’t secure itself. The default settings are built for ease of access, not defence-in-depth. If your IT team hasn’t deliberately hardened your tenant, there’s a high probability you’re exposed right now — and you won’t know it until something goes wrong.
This post covers the five most common Microsoft 365 security mistakes Australian SMEs make, why each one matters, and exactly what to do about it.
Microsoft 365 Security Australia – Why MFA Alone Is Not Enough
Multi-factor authentication (MFA) is the single highest-impact security control available in Microsoft 365. Microsoft’s own data shows that phishing-resistant MFA can block 99% of identity-based attacks. Identity-based attacks surged 32% in 2025, with 97% of them involving stolen or weak passwords (Microsoft Digital Defense Report 2025).
Here’s the problem: enabling MFA and enforcing MFA are two different things. Many organisations turn on the feature but leave significant gaps:
- Service accounts and legacy app accounts are excluded — permanently
- Break-glass admin accounts have no MFA because someone was worried about lockouts
- New users are onboarded without MFA applied to their account from day one
- Legacy authentication protocols (SMTP, IMAP, POP3) are still active and bypass MFA entirely
A CoreView analysis of 1.6 million Microsoft 365 users published in March 2026 found that 87% of organisations had at least some administrators operating without MFA, and MFA was not enabled for 28% of administrators across the sample.
The fix: use Conditional Access policies in Microsoft Entra ID to enforce MFA for all users, all apps, on all devices — with no permanent exclusions. Block legacy authentication at the tenant level. Review your Entra ID sign-in logs monthly for gaps.
Mistake 2: Global Admin Accounts Are Used for Day-to-Day Work
Global Administrator is the most privileged role in Microsoft 365. It can modify security policies, reset any password, access any mailbox, and delete anything. It should almost never be used for routine tasks — and it should never be the account a person logs into daily.
Yet in SME environments, it’s common to see a small IT team where two or three people have Global Admin assigned to their regular user accounts. They use these accounts to read email, join Teams meetings, and browse SharePoint. Every one of those sessions is an elevated-risk event.
Best practice is clear:
- Create dedicated cloud-only admin accounts used only for administrative tasks
- Protect those accounts with phishing-resistant MFA (hardware keys or passkeys, not SMS)
- Apply Privileged Identity Management (PIM) so Global Admin access is time-bound and requires justification
- Remove Global Admin from day-to-day user accounts and assign least-privilege roles instead
Microsoft recommends having no more than five Global Administrators in any organisation. Most SMEs we audit have significantly more, often with no visibility into what those accounts have accessed.
Mistake 3: Microsoft Purview Data Loss Prevention Is Disabled or Untouched
Microsoft 365 Business Premium includes Microsoft Purview Information Protection and basic Data Loss Prevention (DLP) policies. Most organisations have never opened the Purview compliance portal, let alone configured a DLP rule.
The consequence: sensitive data — financial records, employee files, client contracts, health information — flows freely via email, Teams chat, and SharePoint sharing links with no guardrails. A single misdirected email or incorrectly shared SharePoint folder can constitute a notifiable data breach under the Australian Privacy Act.
The Australian Information Commissioner received 527 data breach notifications in the second half of 2024 alone. Human error and malicious external actors were the two leading causes. DLP policies directly address both.
Practical steps for Australian SMEs:
- Enable the Australia-specific DLP templates in Purview (Tax File Numbers, Medicare numbers, credit card data)
- Set policies to audit first — review what’s actually being shared before you block
- Configure sensitivity labels so users understand what data classification means in practice
- Set external sharing restrictions in SharePoint so guest access requires explicit approval
Mistake 4: Microsoft 365 Secure Score Is Ignored
Microsoft Secure Score is a free, built-in dashboard that measures your security posture across identity, devices, apps, and data. Most mid-market companies operating in Australia operate between 40% and 60% (Trusted Tech Team, 2026). A score below 40% is a serious risk indicator.
The problem isn’t just the score itself — it’s that most SMEs never look at it. Secure Score is only useful if someone reviews the recommended actions, prioritises them by impact, and actually implements them. Without that discipline, the gap between where your tenant is and where it should be widens every quarter.
High-impact actions that move the score significantly:
- Enable Microsoft Defender for Office 365 Safe Links and Safe Attachments on all mail
- Require password expiry for non-passwordless accounts
- Enable audit logging across all workloads (it’s off by default in some tenants)
- Configure Microsoft Defender for Business to cover all enrolled devices
At Cloud Solution IT, our clients’ Secure Score increases by more than 30 points within 90 days of engagement — part of the same process that delivers an 87% average reduction in IT incidents. Our team monitors Secure Score continuously as part of a fixed monthly subscription, so there’s no project-by-project cost or guesswork.
Mistake 5: Microsoft 365 Security Australia — No Real Backup Exists
This is the most dangerous misconception in the Microsoft 365 ecosystem: that Microsoft backs up your data. It does not — not in the way you need for recovery.
Microsoft’s shared responsibility model makes this explicit. Microsoft is responsible for infrastructure uptime and replication across data centres. You are responsible for your data. If a user accidentally deletes a SharePoint site, a ransomware attack encrypts your OneDrive files, or a disgruntled employee wipes a shared mailbox, Microsoft’s native retention features will only protect you if they’ve been configured correctly — and even then, retention periods are limited.
The ASD 2024–25 Cyber Threat Report documents cases where Australian businesses lost critical data permanently after ransomware attacks, despite believing they had a backup strategy in place.
The solution is straightforward:
- Implement a dedicated Microsoft 365 backup solution (Veeam, Datto SaaS Protection, or equivalent)
- Back up Exchange Online, SharePoint, OneDrive, and Teams data daily
- Test restoration quarterly — not just backup completion, but actual file and mailbox recovery
- Store backups in a separate tenancy or geographic region so a tenant-level compromise doesn’t affect backup integrity
Frequently Asked Questions
Is Microsoft 365 Business Premium worth the extra cost for security?
For most SMEs with 20 to 200 staff, Business Premium is the right plan. It includes Microsoft Defender for Business, Intune device management, Azure AD Premium P1 (Conditional Access), and Microsoft Purview Information Protection. The security features justify the price difference over Business Standard for any organisation that takes its cyber risk seriously.
How do I check my Microsoft 365 Secure Score?
Log into the Microsoft 365 Defender portal (security.microsoft.com) and navigate to Secure Score. You’ll see your current score, a breakdown of recommended actions, and the estimated score improvement each action delivers. Start with actions marked as high impact and low implementation effort.
Do I need a separate security tool if I have Microsoft 365?
It depends on your plan and risk tolerance. Microsoft Defender for Business (included in Business Premium) covers endpoint detection and response for up to 300 users. For organisations that need 24/7 monitoring, a managed SOC service that wraps around your Microsoft 365 security in Australia gives you detection and response capability without building an in-house security team.
The Bottom Line
Microsoft 365 is one of the most powerful productivity and security platforms available — but it does not secure itself. The five mistakes above are preventable. They require configuration work, not additional spend, and in most cases the tools are already included in your existing subscription.
The ASD’s data is blunt: the average cyber incident now costs Australian medium businesses $97,200 (ASD Annual Cyber Threat Report 2024–25). If you want to know where your Microsoft 365 security stands in Australia today, CSIT offers a no-obligation security assessment to review your configuration against Microsoft best practice. Explore our Microsoft 365 security and compliance services and get in touch to book your assessment.