How to Audit Your Microsoft 365 Security Posture — A Complete Guide

Why audit your Microsoft 365?

Most companies set up Microsoft 365 once and never revisit the security settings. Meanwhile, Microsoft adds new features, threats evolve, and the configuration that was "good enough" 6 months ago no longer is.

A security audit shows you exactly where the gaps are — not what you think is configured, but what's actually active.

What to evaluate in an Microsoft 365 security audit

1. Multi-Factor Authentication (MFA)

MFA is the #1 defense against credential theft. Microsoft reports that 99.9% of account attacks are prevented with MFA enabled.

What to check:

• Is MFA enabled for ALL users, not just administrators?
• Are strong methods (authenticator app) used instead of SMS?
• Are there exceptions that weaken the policy?

Common finding: MFA is enabled for admins but not for regular users. An attacker compromises a regular account, escalates privileges, and bypasses MFA entirely.

2. Conditional Access policies

Conditional Access policies are the brain of your identity security. They define who can access what, from where, on which devices, and under what conditions.

What to check:

• Are there policies that block access from unrecognized locations?
• Do unmanaged devices have restricted access?
• Is MFA required for high-risk actions (admin portals, sensitive data)?

Common finding: No Conditional Access policies exist at all. Any user, from any device, in any country, can access all company data with just a password.

3. Email authentication (SPF, DKIM, DMARC)

Email is the #1 attack vector for SMBs. Without proper email authentication, anyone can send emails pretending to be your domain — and your customers won't be able to tell the difference.

What to check:

• Is SPF configured and limiting authorized senders?
• Is DKIM active for your domain?
• Is DMARC set to "reject" or "quarantine" (not just "none")?
• Is automatic mailbox forwarding disabled?

Common finding: DMARC is set to "none" (monitoring only) — meaning spoofed emails are delivered to recipients without any warning. This is the single most impactful email security fix for most businesses.

4. Data protection (DLP and external sharing)

Data leakage is silent. An employee shares a file with "anyone with the link" and sensitive information is exposed without anyone noticing.

What to check:

• Is external sharing in SharePoint/OneDrive controlled?
• Are there DLP policies for sensitive data (credit cards, personal IDs, tax IDs)?
• Do sharing links expire automatically?

Common finding: OneDrive external sharing is set to "anyone" — meaning any file shared externally is accessible to the entire internet via a guessable URL.

5. Devices and endpoints

If a device is compromised, the attacker inherits all the user's permissions. Without device management, you have no visibility into which machines are accessing your data.

What to check:

• Is Intune configured for device management?
• Is Microsoft Defender active on all endpoints?
• Are there compliance policies that block non-compliant devices?

Common finding: No device management exists. Personal phones, shared computers, and unpatched laptops all have full access to company data.

How to run this audit automatically

simiriki's free scanner evaluates the 155 Microsoft Graph rules of the 201-rule library against your Microsoft 365 tenant. Connect your tenant with one click and read-only access. The preview typically appears in minutes. The complete report is delivered on a best-effort basis, with a non-guaranteed estimated target of up to 1 hour. The 46 Azure Resource Manager controls require separate admin consent and Reader access.

No installation required. No access to emails or files. Just security configuration analysis.

Scan your Microsoft 365 + Azure for free →

What happens after the scan?

Your results include:

• Security posture score (0-100) with letter grade
• Critical findings that need immediate attention
• High-severity findings that represent ongoing risk
• Trend tracking if you subscribe to Operación

For a complete action plan with guided remediation, our free Auditoría includes expert analysis and a 90-day security roadmap.

FAQ

How long does a manual audit take?

A thorough manual audit takes 2-3 days of specialist work. Our automated scanner does it in 90 seconds.

Do I need to give admin access?

No. The scan uses read-only access to security configuration. We don't access emails, files, or user data.

How often should I audit?

At least quarterly. With Operación, scans run automatically every week with email alerts.

What if I find critical issues?

Each finding includes a remediation recommendation. For guided implementation, our Security Audit includes a complete action plan and 30-minute results session.

Does this work for any Microsoft 365 plan?

Yes — Business Basic, Business Standard, Business Premium, E3, E5. The scanner adapts its rules based on your license level.