Microsoft 365 Security Audit: 10 Settings Every Business Should Review

Microsoft 365 is one of the most widely used business platforms in the world, which also makes it one of the most targeted. Most businesses set it up once, add new employees as they get hired, and rarely revisit the security settings buried in the admin center. Over time, default configurations, forgotten permissions, and outdated settings quietly accumulate into real risk, even for businesses that consider themselves security conscious.

CMIT Solutions of Cincinnati East works with local businesses to audit and tighten their Microsoft 365 environments before those gaps turn into an actual incident, whether the business is a longtime client or exploring a local business technology partnership for the first time. This guide walks through ten specific settings every business should review, why each one matters, and how to know if your environment has drifted away from a secure configuration.

Businesses that have not reviewed their Microsoft 365 setup recently should start with a broader look at their current managed IT services coverage to confirm ongoing monitoring is actually happening.

Why Microsoft 365 Security Audits Matter So Much

Microsoft 365 houses email, files, calendars, and collaboration tools for nearly every employee in a business, which makes it an attractive target for attackers. A single compromised account can expose sensitive data, spread phishing attempts to contacts, or grant access to systems far beyond email alone.

Reasons audits often get skipped, even though they matter:

Default settings feel secure enough without a closer look
IT staff assume Microsoft handles security automatically
No one is specifically assigned to review settings regularly
Growing businesses add users faster than they review permissions
Past audits found no issues, creating false long-term confidence

A structured IT self assessment is a useful starting point before diving into the specific settings below.

Multi-Factor Authentication Enforcement

Multi-factor authentication remains one of the single most effective protections against account compromise, yet many businesses still have it only partially enforced, often exempting certain users or leaving it optional entirely.

What to check:

Confirm MFA is required for every user, including executives and administrators
Review whether legacy sign-in methods bypass MFA requirements
Verify conditional access policies actually enforce MFA consistently
Check for any accounts still using password-only authentication

Comprehensive cybersecurity protection services should include ongoing verification that MFA enforcement has not quietly lapsed for any user group over time.

Conditional Access Policy Review

Conditional access policies determine when and how users can sign in, based on factors like location, device compliance, and risk level. Many businesses set these policies up once and never revisit them, even as remote work patterns and device usage change significantly.

Key areas to review:

Whether sign-ins from unfamiliar locations trigger additional verification
Device compliance requirements for accessing company data
Session timeout settings for shared or public devices
Policies covering access from personal versus company-owned devices

Working with a provider offering ongoing IT security guidance helps ensure these policies evolve alongside how the business actually operates rather than staying frozen at initial setup.

Administrator Role Assignments

Excessive administrator access is one of the most common findings during Microsoft 365 audits. Businesses often grant global administrator rights broadly for convenience, when most staff only need access to a narrow set of specific functions.

Audit questions to ask:

How many users currently have global administrator access?
Are role assignments based on least-privilege principles?
Have former employees or contractors retained admin access?
Is privileged access reviewed on a regular schedule?

This directly supports broader adoption of zero trust adoption principles, which limit access based on verified need rather than default convenience. Firms handling especially sensitive files often go a step further, adopting law firm access controls style permission structures across their entire Microsoft 365 environment, not just legal-specific systems.

Mailbox Forwarding and Auto-Forwarding Rules

Attackers who gain access to an email account frequently set up hidden auto-forwarding rules to quietly receive copies of sensitive emails without the account owner noticing. These rules can sit unnoticed for months, silently leaking information the entire time.

Businesses should regularly check for:

Unauthorized forwarding rules sending mail to external addresses
Rules created outside of normal business hours
Forwarding configured to hide or delete forwarded messages
Bulk review of forwarding rules across all mailboxes, not just flagged accounts

Reviewing recent trends in AI tool risks is also relevant here, since compromised accounts are increasingly used to feed sensitive email content into unauthorized AI tools without detection.

External Sharing Settings in SharePoint and OneDrive

Default sharing settings in SharePoint and OneDrive often allow broader external access than most businesses realize, sometimes permitting anonymous links to sensitive files without any additional verification required.

Settings worth reviewing:

Whether anonymous, no-login-required sharing links are enabled
Expiration dates on external sharing links
Whether external sharing is limited to approved domains only
Visibility into how many files are currently shared externally

Ongoing data backup protection should be reviewed alongside sharing settings, since overly permissive sharing can complicate recovery efforts if sensitive files are exposed or modified without authorization. Businesses relying on broader cloud services support should confirm sharing policies are reviewed as part of that ongoing relationship rather than left to a one-time setup.

Legacy Authentication Protocols

Older authentication protocols were not designed with modern security threats in mind and often bypass multi-factor authentication entirely. Many businesses still have these protocols enabled without realizing it, simply because disabling them was never revisited after initial setup.

What to disable or restrict:

Basic authentication for email protocols like POP and IMAP
Legacy versions of Exchange ActiveSync where not needed
Older authentication methods still supported for compatibility reasons
Any protocol that does not support modern conditional access policies

This is a common gap uncovered during broader reviews of cybersecurity mistakes owners make when managing cloud platforms, since legacy protocols rarely get attention until an audit specifically looks for them.

Audit Logging and Alert Configuration

Microsoft 365 includes extensive logging capabilities, but many businesses never turn on the right alerts or review logs regularly enough to catch suspicious activity early. Without proper logging, a compromised account can go unnoticed for weeks.

Logging and alerting should cover:

Unusual sign-in locations or impossible travel scenarios
Mass file downloads or unusual data access patterns
Failed multi-factor authentication attempts in high volume
Changes to administrator roles or security policy settings

Reliable network security management practices should extend into cloud platforms like Microsoft 365, not just on-premises network infrastructure.

Data Loss Prevention Policies

Data loss prevention policies help prevent sensitive information, such as financial data or personal records, from being shared inappropriately, whether intentionally or by accident. Many businesses never configure these policies at all, missing a valuable layer of protection.

Areas to configure:

Detection rules for sensitive data types relevant to your industry
Policies restricting sharing of flagged content outside the organization
Notifications alerting users when a policy violation is detected
Regular review of policy effectiveness and false positive rates

Businesses in regulated industries should pair this with ongoing compliance monitoring services to confirm data handling practices meet applicable regulatory requirements. Evaluating new security add-ons through proper licensing procurement services also helps avoid purchasing overlapping tools that duplicate built-in Microsoft 365 protections.

Mobile Device Management and Access Controls

Employees increasingly access Microsoft 365 from phones and tablets, which introduces risk if those devices are not properly managed. Lost or stolen devices, outdated operating systems, and unmanaged personal devices can all become entry points for unauthorized access.

Mobile access review should include:

Whether company data can be accessed from unmanaged personal devices
Remote wipe capabilities for lost or stolen devices
Minimum operating system requirements for device compliance
App protection policies separating business and personal data

This is especially relevant for businesses expanding their use of unified communications support across mobile devices, since communication tools often carry sensitive conversations that need the same level of protection as email.

Microsoft Teams External Access Settings

Teams has become a primary communication hub for many businesses, but default settings often allow broader external access than intended, letting outside users join calls or send messages without proper restrictions in place.

Settings to review:

Whether external users can freely message internal employees
Guest access permissions and how they are approved
Screen sharing and file sharing permissions for external participants
Whether external access is limited to approved partner organizations

Reviewing Microsoft 365 support options that include Teams-specific configuration review helps ensure this widely used tool does not become an overlooked security gap.

Signs Your Microsoft 365 Environment May Already Be Compromised

Beyond a scheduled audit, certain warning signs suggest an account or environment may already be at risk:

Employees reporting emails they never sent appearing in their sent folder
Unexpected password reset notifications
Colleagues receiving suspicious emails that appear to come from internal staff
Unfamiliar sign-in locations appearing in account activity
New forwarding rules or mailbox settings no one recalls configuring

Understanding how frequently small business targeting occurs through compromised cloud accounts reinforces why these warning signs should never be dismissed as minor annoyances.

Industry-Specific Microsoft 365 Considerations

Different industries face different risks when it comes to cloud collaboration platforms, and audits should reflect those specific concerns.

Legal practices handling confidential client files should prioritize legal practice protection measures around external sharing and mailbox forwarding rules.
Accounting firms managing financial data face frequent accounting firm targeting attempts, making mailbox security review especially critical during tax season.
Engineering firms storing proprietary designs need strong access restrictions around SharePoint and OneDrive external sharing to keep sensitive project files protected.
Healthcare practices should align Microsoft 365 settings with broader healthcare security practices covering patient data protection requirements.
Manufacturers investing in modern systems should review Microsoft 365 alongside other manufacturer cybersecurity investment decisions ahead of scheduled audits.

New Threats Making These Settings More Important Than Ever

Attack methods continue to evolve, making regular Microsoft 365 audits even more important than they were just a few years ago. Newer tactics like QR code phishing are specifically designed to bypass traditional email security filters, making conditional access and multi-factor authentication even more critical layers of defense.

Businesses should also watch how competitors using AI tools are integrating with Microsoft 365 environments, since new AI features often request broad permissions that deserve the same scrutiny as any other third-party integration. A dedicated AI readiness assessment can help determine which AI integrations are safe to enable within your current environment.

Building an Ongoing Review Process

A one-time audit provides value, but Microsoft 365 environments change constantly as employees join, leave, and adopt new features. A sustainable review process should include:

Quarterly review of administrator roles and permissions
Monthly check of new or unusual mailbox forwarding rules
Ongoing monitoring of sign-in activity and failed authentication attempts
Annual full review of conditional access and sharing policies
Immediate review of settings after any reported suspicious activity

Reviewing available security service packages helps clarify what level of ongoing Microsoft 365 monitoring is included as part of a broader IT support relationship. Growing companies building new systems from scratch should also reference a solid startup technology foundation to make sure Microsoft 365 security is built in from day one rather than added later. Working with dedicated IT support also ensures identified issues actually get resolved rather than sitting in a report no one acts on.

Choosing a Partner to Handle These Reviews

Not every provider treats Microsoft 365 security with the depth it deserves. Businesses should confirm a potential partner has specific experience auditing cloud collaboration platforms, not just general network security.

An experienced security provider should be able to walk through findings clearly and provide a prioritized remediation plan. Working with local security team members who understand regional compliance requirements adds an extra layer of confidence that nothing gets overlooked during the review process.

Ready to Find Out What Your Microsoft 365 Environment Is Missing?

Default settings rarely stay secure forever, and small gaps in Microsoft 365 configuration can quietly expose a business to real risk. From multi-factor authentication to external sharing settings, each of these ten areas deserves regular attention rather than a one-time check. CMIT Solutions of Cincinnati East helps local businesses review these settings thoroughly and build a plan to keep them secure going forward.

If your Microsoft 365 environment has not been reviewed recently, schedule a consultation to find out exactly where your current setup stands.

Frequently Asked Questions

1. How often should a business audit its Microsoft 365 security settings?+

A full review at least twice a year is a practical baseline for many businesses, with more frequent checks for high-risk areas such as administrator roles, mailbox rules, third-party app permissions, and suspicious sign-in activity.

2. Is multi-factor authentication really necessary for every employee?+

Multi-factor authentication should be enforced wherever possible for all users, with especially strong protection for administrators, executives, finance staff, and accounts with access to sensitive information.

3. What is conditional access, and why does it matter?+

Conditional access applies security rules based on factors such as user identity, device status, location, application, and sign-in risk. It allows businesses to require stronger verification or block access when conditions do not meet approved security requirements.

4. How many people should have global administrator access?+

Global administrator access should be limited to the smallest practical number of trusted users. Routine tasks should be assigned through more limited administrative roles whenever possible to reduce unnecessary privilege.

5. What are mailbox forwarding rules, and why are they a security concern?+

Mailbox forwarding rules automatically send copies of messages to another destination. Attackers sometimes create hidden or unexpected rules after compromising an account, allowing them to monitor sensitive communications without the user realizing it.

6. Should external sharing be disabled entirely in SharePoint and OneDrive?+

Not necessarily. External sharing can support legitimate collaboration, but it should be governed with appropriate permissions, expiration settings, authentication requirements, and restrictions on anonymous or overly broad links.

7. What is legacy authentication, and why should it be disabled?+

Legacy authentication refers to older sign-in methods that may not support modern controls such as multi-factor authentication and conditional access. Where no longer required for legitimate systems, disabling older protocols can reduce account compromise risk.

8. Does Microsoft 365 include built-in security logging?+

Yes. Microsoft 365 and Microsoft Entra provide audit, sign-in, and security-related logging capabilities. Their usefulness depends on licensing, configuration, retention, alerting, and whether someone is actively reviewing the information.

9. What is a data loss prevention policy?+

A data loss prevention policy uses rules to identify and help protect sensitive information from being shared, copied, or transmitted in ways that violate the organization’s security or compliance requirements.

10. How does mobile device management improve Microsoft 365 security?+

Mobile device management can enforce security requirements on devices accessing company data, such as screen locks, encryption, compliance checks, approved applications, and remote removal of business information from lost or unmanaged devices.

11. Are Microsoft Teams settings often overlooked during security audits?+

They can be. Guest access, external communication, app permissions, file sharing, meeting settings, and team ownership should all be reviewed to ensure they still match the organization’s collaboration and security requirements.

12. What are common signs an account has already been compromised?+

Warning signs can include unfamiliar sign-ins, unexpected password or MFA changes, unusual sent messages, new mailbox forwarding rules, suspicious inbox rules, unfamiliar applications, and login activity from unexpected devices or locations.

13. Do small businesses really need a formal Microsoft 365 audit?+

Yes. Small businesses depend heavily on Microsoft 365 for email, files, identities, and collaboration, so reviewing configuration and permissions can uncover security gaps that may otherwise remain unnoticed.

14. How does AI tool adoption affect Microsoft 365 security?+

AI integrations may request access to email, documents, calendars, contacts, or other Microsoft 365 data. Their permissions, vendor security, data handling, and business purpose should be reviewed just like other third-party applications.

15. Can Microsoft 365 security settings affect regulatory compliance?+

Yes. Identity controls, logging, retention, information protection, sharing, device management, and data loss prevention settings can affect an organization’s ability to meet applicable privacy, security, contractual, and industry requirements.

16. What is the biggest mistake businesses make with Microsoft 365 security?+

A common mistake is assuming the initial or default configuration will remain appropriate indefinitely. Security settings, permissions, applications, users, and business requirements should be reviewed as the organization changes.

17. How long does a full Microsoft 365 security audit typically take?+

The timeline depends on the number of users, applications, administrative roles, compliance requirements, and audit scope. A smaller environment may take several days, while a more complex review can require one or two weeks or longer.

18. Should audit findings be addressed immediately or can they wait?+

Findings should be prioritized according to severity, likelihood, exposure, and business impact. High-risk issues such as excessive administrator access, weak authentication, suspicious forwarding rules, or exposed data should generally receive prompt attention.

19. Can a Microsoft 365 audit help with cybersecurity insurance requirements?+

Yes. A documented audit can help businesses verify controls such as multi-factor authentication, administrative access, logging, email security, and cloud permissions when responding to cyber insurance applications or renewal questionnaires.

20. Where should a business start if it has never reviewed these settings?+

Start by reviewing multi-factor authentication, administrator roles, legacy authentication, external sharing, suspicious mailbox rules, third-party app permissions, and sign-in activity. These areas often provide a strong foundation for a broader Microsoft 365 security audit.

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