Facts to Remember
Microsoft 365 audit logs track user, admin, and system activities across services like Exchange, SharePoint, and Teams, helping with security monitoring and compliance.
Logs include details such as timestamps, user identities, activity types, and target items, providing critical insights for detecting unauthorized access and policy violations.
Audit logs have limitations, including retention restrictions (180 days by default) and the inability to store actual file contents, making long-term data recovery reliant on backups.
A robust data protection strategy should integrate audit logs with backup solutions to ensure the recoverability of critical files and emails in case of accidental deletion, cyberattacks, or compliance needs.
Microsoft 365 audit logs record user and admin activity across your organization. They help you track changes, monitor security, and investigate issues. But understanding what these logs capture—and more importantly, how to read them—can be overwhelming.
This article details what M365 audit logs contain and how to interpret them efficiently.
Must-Know Information About Microsoft 365 Audit Logs
Microsoft 365 audit logs provide a detailed record of activities across Exchange Online, SharePoint, OneDrive, Teams, and other Microsoft 365 services. They help you monitor security, investigate incidents, and ensure compliance with regulations like the General Data Protection Regulation (GDPR), the Health Insurance Portability and Accountability Act (HIPAA), and ISO 27001. By tracking user actions, administrator changes, and system events, these logs are a powerful tool for both operational oversight and forensic investigations.
Microsoft 365 audit logs capture events from multiple services, including:
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Exchange Online – Email sends and receives, mailbox access, and delegation modifications.
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SharePoint & OneDrive for Business – File access, sharing, deletions, and modifications.
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Microsoft Teams – Messages sent, channel changes, and file sharing.
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Azure Active Directory (Entra ID) – User sign-ins, failed login attempts, and privilege escalations.
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Power Automate & Power BI – Workflow executions and data access.
These logs track three main types of activities: user activities (opening, editing, deleting files, sending emails, and logging in), administrator activities (creating or deleting accounts, modifying permissions, and enabling or disabling features), and system-generated logs (automatic enforcement of retention policies and background synchronization processes).
Accessing Microsoft 365 audit logs requires appropriate permissions, such as the “Audit Logs” or “View-Only Audit Logs” roles. To search logs in the Microsoft Purview Compliance Portal, sign in to Microsoft Purview Compliance Portal, maneuver through to Solutions > Audit, and then use the search bar to filter logs by user, activity type, service, or time range.
For more advanced searches, you can use PowerShell. To check if audit logging is enabled, run this command: Get-AdminAuditLogConfig | Format-List UnifiedAuditLogIngestionEnabled. This will confirm whether Unified Audit Logging is turned on. If you need to retrieve logs from the past seven days, use: Search-UnifiedAuditLog -StartDate (Get-Date).AddDays(-7) -EndDate (Get-Date).
Microsoft 365 retains audit logs for 180 days by default, but E5 licenses extend retention by up to one year. You can also export logs as CSV files for deeper analysis in Excel, Power BI, or Security Information and Event Management (SIEM) tools.
How to Read and Interpret M365 Audit Logs
Key Components of an M365 Audit Log Entry
Understanding the key components of a Microsoft 365 audit log entry helps you track user activities, detect security threats, and ensure compliance. Each log entry contains structured data fields that provide context about an event, allowing you to analyze what occurred and who was involved.
Each log entry includes several key attributes such as date and time (when the action occurred, recorded in UTC format), user (the account that performed the action, and details such as IP address and device information), activity type (a description of the event, such as file accessed, email sent, or user signed in), target item (the specific object affected, which could be a file, email, or user account), and operation status (whether the action succeeded or failed).
By understanding these components, you can extract meaningful insights from log data. For example, if you see an entry with “FileDeleted” as the activity type and a sensitive document as the target, you should verify whether the action was authorized. This information is critical for security monitoring, troubleshooting, and compliance reporting.
Common M365 Audit Log Events and What They Indicate
M365 audit logs capture a wide range of activities, from user authentication to administrative changes, providing insight into potential risks. Recognizing common log events can help identify security threats and operational issues.
User authentication events play a key role in identifying unauthorized access attempts. Successful login events indicate normal user activity but should be checked for access patterns at unusual hours while failed login attempts, especially multiple failures in a short period, might suggest brute-force attacks. Unusual login locations can signal a compromised account, especially if the access attempt comes from an unexpected geographic region or IP address.
File and data access events help track how users interact with sensitive information. File accessed/viewed logs show user activity but should be monitored for unauthorized access to confidential data. File downloaded/copied in large volumes or by an unusual user might indicate data exfiltration attempts. File deletions and restorations can indicate accidental loss, insider threats, or attempts to erase evidence of malicious actions.
Administrative and security changes can reveal security risks if unauthorized modifications occur. Permission changes should be reviewed to ensure users don’t receive unnecessary privilege escalations, while account creations/deletions might indicate legitimate user management but should be investigated if unexpected. Altered security settings, such as multi-factor authentication (MFA) or audit policy changes, may suggest an attacker is trying to establish persistence.
Best Practices for Identifying Suspicious or Anomalous Activities
Detecting suspicious activity in Microsoft 365 audit logs requires a structured approach. Isolated events can be misleading, but recognizing patterns and correlations helps you identify risks more effectively.
First, set up alerts for high-risk events to catch potential security threats in real time. Configure notifications for failed login attempts, admin role changes, and file deletions in critical locations. These events often signal unauthorized access attempts or insider threats.
Next, monitor patterns instead of individual events to detect attacks like credential stuffing. A single failed login is common, but multiple failures followed by a successful login could indicate an attacker gaining access. Look for sequences of suspicious actions instead of isolated incidents.
Also, compare logs across different Microsoft 365 services to see the full picture. Events in Entra ID, Exchange, and SharePoint might seem unrelated, but analyzing them together can reveal coordinated attacks or policy violations.
To streamline analysis, use filters to narrow down logs based on date, user, or activity type. This helps you quickly focus on anomalies instead of manually sifting through large volumes of raw data.
Regularly review and export logs to maintain visibility beyond Microsoft’s default retention periods. Long-term monitoring allows you to detect slow-moving threats that unfold over weeks or months.
For more advanced detection, leverage PowerShell or third-party SIEM tools to automate log analysis. These tools can flag unusual patterns, reducing the burden of manual review and improving response times.
Limitations of Microsoft 365 Audit Logs
Microsoft 365 audit logs provide valuable insights into user activity but have significant limitations that impact security, compliance, and data retention. Understanding these constraints helps determine whether additional measures are necessary to protect your data.
Retention policies and storage constraints are major challenges. Standard Microsoft 365 licenses (E3 and lower) retain logs for only 180 days, while an E5 license extends this to one year. Long-term retention requires manual exports or third-party solutions since Microsoft controls log storage, limiting archiving and retrieval beyond the retention period. In high-volume environments, logs may take time to generate, delaying access to historical data, and once expired, they are permanently lost.
Audit logs also have critical gaps in the information they capture. While they track user actions, they do not store actual file contents, meaning deleted documents cannot be recovered from logs alone. Logs are not always generated in real time, and attackers with privileged access can disable or erase them to cover their tracks. Additionally, third-party applications integrating with Microsoft 365 may operate outside audit logging, creating blind spots in monitoring.
Because of these limitations, audit logs alone cannot ensure data protection. They provide visibility but do not prevent data loss, recover deleted files, or protect against ransomware and insider threats. Many industries require long-term retention beyond Microsoft’s capabilities, making a dedicated backup solution like Nexetic Backup for Microsoft 365 essential for compliance and data recovery. Start a free trial or schedule a consultation to see how it works for your organization.
Strengthening Data Protection: The Role of Backup in Microsoft 365
Data protection in Microsoft 365 depends on both audit logs and backup solutions, but they serve different purposes. Audit logs can show what happened but cannot restore the lost information. A dedicated backup solution complements audit logs by ensuring that files, emails, and other critical data remain recoverable. Backups create snapshots of data at regular intervals, offering a way to restore information even if audit logs are erased or altered.
This protects against accidental deletions, insider threats, and ransomware attacks. Also, backups help organizations meet compliance requirements by retaining data beyond Microsoft’s default retention periods.
To maximize security, businesses should integrate audit logs with a robust backup strategy:
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Enable continuous logging and backup to maintain real-time visibility and data protection.
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Use audit logs to monitor unusual activity and verify that critical data is backed up before incidents occur.
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Set up automated alerts for high-risk events, such as mass deletions, and ensure backup versions exist for affected files.
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Regularly test data recovery to confirm that backups are functional and meet compliance needs.
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Store backups separately from Microsoft 365 to prevent attackers from erasing both logs and backup data.
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Implement strict access controls to prevent unauthorized modifications of logs and backups.
A strong backup strategy ensures that data remains recoverable, even if logs are compromised or deleted.
Next Steps: Bridging the Gap Between Audit Logs and Data Security
Microsoft 365 audit logs are a powerful tool for tracking user activity, monitoring security, and ensuring compliance. They help identify anomalies, investigate incidents, and maintain operational oversight. However, their retention limits, lack of real-time alerts, and inability to restore deleted data create gaps in long-term data protection. To truly safeguard critical information, organizations need a backup strategy that goes beyond audit logs.
Nexetic Backup for Microsoft 365 fills that gap by offering fully automated, secure backups with unlimited version history, instant data restoration, unparalleled scalability, and advanced security—all without manual intervention. Start a free trial or book a quick demo today for an up-close look at how it strengthens your data protection strategy.
FAQ
What is the purpose of Microsoft 365 audit logs?
Microsoft 365 audit logs track user, admin, and system activities across Microsoft 365 services. They help organizations monitor security, investigate incidents, and ensure compliance by providing a detailed record of actions like file access, email activity, sign-ins, and configuration changes.
How can I access Microsoft 365 audit logs?
Audit logs can be accessed through the Microsoft Purview Compliance Portal under Solutions > Audit by using search filters. Advanced users can retrieve logs with PowerShell commands, allowing more granular searches and automation for security monitoring and compliance checks.
How long are Microsoft 365 audit logs retained?
Microsoft 365 audit logs are retained for 180 days by default. Organizations with an E5 license can extend this period to one year. Longer retention requires exporting logs manually or integrating with third-party storage and security solutions.
What are the limitations of Microsoft 365 audit logs?
Audit logs record actions but do not store actual data. They have limited retention periods, may be delayed in generating logs, and can be tampered with by attackers who disable logging or erase records, making them insufficient for full data protection.
How does backup complement Microsoft 365 audit logs?
Backup solutions ensure that critical data remains recoverable, even if audit logs show deletions or unauthorized modifications. While logs track actions, backups preserve the actual files and emails, allowing organizations to restore lost data, meet compliance requirements, and protect against cyber threats.
