Microsoft 365 Tenant Security Audit: The Complete Guide
Identity, email, data, endpoints, compliance, and Copilot readiness. EPC Group's 47-Point Framework covers what Microsoft Secure Score misses.
Why Tenant Security Audits Matter Now
Quick Answer: A Microsoft 365 tenant security audit examines six domains — identity, email, data protection, endpoints, compliance, and Copilot readiness — to identify misconfigurations, permission gaps, and compliance risks. The average enterprise has 15-25 critical findings in their first audit. With Copilot now inheriting user permissions, unaudited tenants are exposing sensitive data through AI-powered search without knowing it.
Your Microsoft 365 tenant is the operating system of your business. Email flows through it. Documents live in it. Meetings happen on it. Identity is managed by it. And now, with Microsoft Copilot, AI queries every piece of data inside it. A security gap in your tenant is not a theoretical risk — it is an active exposure surface that grows every time a new user is onboarded, a new site is created, or a new sharing link is generated.
Yet most organizations treat M365 security like a one-time setup task. They configure MFA during initial deployment, set some basic DLP policies, and never revisit. Configuration drift, staff turnover, new service deployments, and the introduction of Copilot create gaps that accumulate silently. The average enterprise tenant we audit has been live for 5-8 years with no comprehensive security review.
EPC Group has audited over 700 Microsoft 365 tenants across healthcare, financial services, government, and Fortune 500 enterprises. Our 47-Point Security Framework was developed from patterns we see repeatedly — the same 15-20 critical gaps appear in nearly every tenant we assess. This guide walks you through what to audit, how to audit it, and when to bring in professionals.
The Copilot Factor: Before Copilot, a SharePoint site with overshared permissions was a latent risk — someone would have to navigate to the site and browse its contents to find sensitive data. With Copilot, that same overshared content is now surfaced proactively in response to natural language queries. Every permission gap in your tenant becomes an active data exposure path the moment you enable Copilot.
What to Audit: The Six Security Domains
A thorough M365 tenant audit covers six interconnected domains. Gaps in one domain compound risks in others — weak identity controls make data protection policies ineffective, and missing endpoint management undermines Conditional Access.
Identity & Access Management
- MFA enforcement across all user accounts and admin roles
- Conditional Access policies — location, device, risk-based
- Privileged Identity Management (PIM) for admin roles
- Guest and external user access review
- Service account inventory and credential rotation
- Break-glass emergency access account configuration
- Legacy authentication protocol elimination
- Sign-in risk and user risk policies (Entra ID P2)
Email Security
- Anti-phishing policies (impersonation protection, mailbox intelligence)
- Safe Attachments and Safe Links configuration
- DMARC, DKIM, and SPF record validation
- Outbound spam and bulk mail policies
- Mail flow rules audit (hidden forwarding rules)
- Quarantine policies and end-user access
- Attack simulation training enrollment
Data Protection
- Sensitivity label taxonomy and deployment status
- Auto-labeling policies for PII, PHI, financial data
- DLP policies across Exchange, SharePoint, Teams, OneDrive
- SharePoint external sharing settings (tenant and site level)
- SharePoint permission inheritance audit — broken inheritance sites
- OneDrive sharing defaults and link expiration
- Information barriers between regulated departments
- Azure Information Protection scanner results
- Copilot data exposure analysis (permission inheritance)
Endpoint Management
- Intune device compliance policies
- Conditional Access device trust requirements
- App protection policies (MAM for BYOD)
- Windows Update for Business ring configuration
- BitLocker encryption enforcement
- Microsoft Defender for Endpoint onboarding status
- Device inventory and stale device cleanup
Compliance & Governance
- Unified audit log enabled and retention configured
- Retention policies across Exchange, SharePoint, Teams
- eDiscovery case management and hold policies
- Communication compliance policies (if regulated)
- Insider risk management configuration
- Data lifecycle management automation
- Compliance Manager score and improvement actions
- Regulatory compliance mapping (HIPAA, SOC 2, FedRAMP)
Copilot & AI Readiness
- SharePoint oversharing analysis (sites accessible to "Everyone")
- Sensitivity label enforcement on Copilot-accessible content
- DLP policies for Copilot-generated outputs
- Teams meeting recording and transcription policies
- Information barriers preventing cross-department data leakage
- Guest access review (Copilot can surface guest-shared content)
- Stale and outdated content inventory
- Copilot usage monitoring and audit logging
EPC Group's 47-Point Security Framework
Our 47-Point Framework was built from auditing 700+ tenants. It covers the 23 critical areas that Microsoft Secure Score misses entirely — including SharePoint permission inheritance analysis, Copilot data exposure modeling, and compliance-specific configurations for HIPAA, SOC 2, and FedRAMP.
What You Get
- 47 specific security checkpoints across 6 domains
- Pass / Fail / Partial rating for each checkpoint
- Risk severity classification (Critical, High, Medium, Low)
- Specific remediation steps with estimated effort
- Copilot readiness score with data exposure analysis
- 40+ page report with executive summary
- Prioritized remediation roadmap (30/60/90 day)
- Compliance mapping to HIPAA, SOC 2, or FedRAMP
What Secure Score Misses
- SharePoint permission inheritance analysis
- Copilot data exposure risk modeling
- Sensitivity label enforcement effectiveness
- Cross-service data flow analysis
- Custom DLP policy quality assessment
- Teams meeting recording policy gaps
- Guest access cumulative exposure
- Stale content and outdated policy detection
DIY Audit vs. Professional Assessment
| Criteria | DIY (Secure Score + Admin Center) | Professional (EPC 47-Point) |
|---|---|---|
| Coverage | 40-50% of security gaps | 95%+ of security gaps |
| Identity & Access | MFA and basic CA policies | PIM, risk policies, service accounts, break-glass |
| SharePoint Permissions | Not covered by Secure Score | Full inheritance analysis across all sites |
| Copilot Readiness | Not covered | Data exposure modeling and remediation plan |
| Compliance Mapping | Generic compliance score | Industry-specific (HIPAA, SOC 2, FedRAMP) |
| Remediation Plan | Generic Microsoft recommendations | Prioritized 30/60/90 day roadmap with effort estimates |
| Cost | Free (staff time only) | $15,000 (2-3 week engagement) |
| Time to Complete | 1-2 weeks (part-time) | 2-3 weeks (dedicated team) |
Our Recommendation: Start with a DIY review using Microsoft Secure Score to address the obvious gaps — enable MFA, disable legacy auth, configure basic DLP. Then bring in a professional assessment for the deeper analysis: SharePoint permission inheritance, Copilot data exposure, compliance-specific configurations, and cross-service risk analysis. The $15,000 investment pays for itself by preventing a single data exposure incident.
Audit Frequency: How Often Should You Review?
Annual: Full 47-Point Assessment
Every organization should conduct a full-scope security audit annually. Configuration drift, staff turnover, new Microsoft features, and evolving threat landscape require a comprehensive reassessment. Annual audits are also required by most compliance frameworks (HIPAA, SOC 2, FedRAMP).
Quarterly: High-Risk Domain Review
Review identity and access (new admin accounts, Conditional Access changes), SharePoint sharing settings (new sites, changed permissions), and DLP policy effectiveness quarterly. These areas change most frequently and have the highest impact when misconfigured.
Trigger-Based: Event-Driven Audits
Conduct targeted audits after: deploying Copilot or other AI services, experiencing a security incident or near-miss, completing a merger or acquisition (tenant-to-tenant migration), regulatory requirement changes, significant staff turnover (especially IT admins), or enabling new M365 services (Teams Phone, SharePoint Premium, Viva).
Continuous: Automated Monitoring
Supplement periodic audits with continuous monitoring: Microsoft Secure Score tracking, Defender for Cloud Apps alerts, unified audit log analysis, and Copilot usage monitoring. Automated alerts catch configuration changes and anomalous access patterns between formal audits.
Post-Audit Remediation: The 30/60/90 Day Approach
An audit without remediation is a report that gathers dust. EPC Group delivers every audit with a prioritized remediation roadmap organized into three phases based on risk severity and implementation effort.
Days 1-30: Critical Fixes
- Enforce MFA on all admin accounts (same day)
- Disable legacy authentication protocols
- Revoke "Everyone except external users" permissions on sensitive SharePoint sites
- Enable unified audit log if not already active
- Configure break-glass emergency access accounts
- Remove stale guest accounts and external sharing links
Days 31-60: High Priority
- Deploy Conditional Access policies (location, device, risk-based)
- Implement sensitivity label taxonomy and begin deployment
- Configure DLP policies for Exchange, SharePoint, Teams, and OneDrive
- Complete SharePoint permission inheritance remediation
- Enable Privileged Identity Management (PIM) for admin roles
- Deploy Intune compliance policies for managed devices
Days 61-90: Optimization
- Auto-labeling policies for PII, PHI, and financial data
- Information barriers between regulated departments
- Retention policies aligned with compliance requirements
- Copilot readiness validation and controlled pilot deployment
- Insider risk management policy configuration
- Continuous monitoring dashboards and alert configuration
Frequently Asked Questions
How do you audit your Microsoft 365 tenant for security?
A comprehensive M365 tenant security audit examines six domains: identity and access management (Entra ID, MFA, Conditional Access), email security (anti-phishing, DMARC, safe attachments), data protection (sensitivity labels, DLP policies, sharing settings), endpoint management (Intune compliance, device policies), compliance posture (retention policies, audit logs, eDiscovery), and Copilot readiness (permission inheritance, oversharing). EPC Group's 47-Point Framework covers all six domains in a structured assessment that takes 2-3 weeks to complete.
How often should you perform a Microsoft 365 security audit?
Organizations should perform a full M365 security audit at minimum annually, with quarterly reviews for high-risk areas. Trigger-based audits should occur after: deploying new services (Copilot, Teams Phone, SharePoint Premium), experiencing a security incident, changing compliance requirements, completing mergers or acquisitions, or significant staff turnover. Continuous monitoring through Microsoft Secure Score, Defender for Cloud Apps, and audit log analysis supplements periodic full audits.
What is Microsoft Secure Score and why does it matter?
Microsoft Secure Score is a numerical representation (0-100%) of your tenant's security posture based on Microsoft's recommendations. The average enterprise scores 40-55%. Scores above 70% indicate strong security hygiene. However, Secure Score has significant blind spots: it doesn't evaluate SharePoint permission inheritance, sensitivity label enforcement effectiveness, Copilot data exposure risk, or custom DLP policy quality. EPC Group's 47-Point Framework covers 23 areas that Secure Score misses entirely.
What are the most common M365 tenant security gaps?
The five most common security gaps we find during audits are: 1) MFA not enforced for all accounts — 34% of enterprises still have admin accounts without MFA, 2) SharePoint "Everyone except external users" permissions granting access to sensitive sites, 3) No sensitivity labels deployed or labels configured but not enforced, 4) Legacy authentication protocols still enabled (a top vector for credential stuffing attacks), 5) No DLP policies for Teams chat or Copilot-generated content. Most organizations have 15-25 critical findings in their first audit.
Should I do a DIY security audit or hire a consultant?
DIY audits using Microsoft Secure Score and the M365 admin center catch approximately 40-50% of security issues — primarily configuration-level gaps with clear Microsoft recommendations. Professional audits catch the remaining 50-60%: permission inheritance analysis, cross-service data flow risks, compliance gaps specific to your industry (HIPAA, SOC 2, FedRAMP), Copilot readiness assessment, and contextual risk prioritization. For regulated industries, a professional audit is not optional — auditors and regulators expect third-party validation.
What does EPC Group's 47-Point Security Framework include?
EPC Group's 47-Point Framework covers six security domains: Identity & Access (8 points: MFA enforcement, Conditional Access policies, PIM configuration, guest access controls, service account audit, break-glass accounts, legacy auth elimination, sign-in risk policies), Email Security (7 points), Data Protection (9 points), Endpoint Management (7 points), Compliance & Governance (8 points), and Copilot & AI Readiness (8 points). Each point receives a Pass/Fail/Partial rating with specific remediation steps, priority level, and estimated effort. The assessment takes 2-3 weeks and includes a 40+ page report with executive summary.
How much does a Microsoft 365 security audit cost?
Professional M365 security audit costs range from $8,000-$50,000 depending on scope: Basic audit (identity + email only): $8,000-$15,000. Comprehensive audit (all six domains): $15,000-$30,000. Enterprise audit with remediation roadmap (6+ domains, compliance mapping, Copilot readiness): $25,000-$50,000. EPC Group's 47-Point Security Review is $15,000 for the full six-domain assessment with detailed remediation roadmap. Remediation is typically scoped separately at $150-$250/hour depending on complexity.
Get Your Tenant Audited by the Experts
EPC Group performs Copilot & M365 Tenant Security Reviews for enterprises across all industries. With 700+ tenants secured and 29 years of Microsoft expertise, we identify exactly what Copilot can access that it shouldn't.
Start with our 47-Point Security Review ($15,000). You will receive a 40+ page report with Pass/Fail ratings, risk classifications, and a prioritized 30/60/90 day remediation roadmap.