Exchange Online, part of Microsoft 365’s suite of cloud-based services, provides a robust platform for managing emails, calendars, and contacts. Mailbox permissions, which determine who can access a mailbox and at what level, are crucial for managing organizational communication. Monitoring changes to these permissions is essential for security, compliance, and ensuring proper access control. In this article, we’ll explore how to detect mailbox permission changes in Exchange Online to maintain a secure email environment.
Enable Mailbox Audit Logging
Mailbox audit logging is a crucial feature in Exchange Online that allows administrators to track actions that modify mailbox permissions. Before detecting mailbox permission changes, ensure that mailbox audit logging is enabled for the mailboxes you wish to monitor.
- Sign in to the Microsoft 365 Compliance Center: Navigate to the Microsoft 365 Compliance Center and sign in using administrative credentials.
- Access the Audit Log Search: Under “Search & investigation,” select “Audit log search.”
- Configure Mailbox Audit Logging: Configure mailbox audit logging settings, including what actions to audit (e.g., SoftDelete, HardDelete, SendOnBehalf), and select the mailboxes you want to monitor.
Utilize PowerShell for Advanced Monitoring
While the audit log search provides a user-friendly interface for viewing mailbox audit logs, using PowerShell allows for more advanced and automated monitoring of mailbox permission changes.
- Connect to Exchange Online PowerShell: Open PowerShell and connect to Exchange Online using the following command:
Connect-ExchangeOnline - Enable Mailbox Auditing: Use PowerShell to enable mailbox auditing for specific mailboxes:
Set-Mailbox -Identity <MailboxIdentity> -AuditEnabled $true - Search for Audit Logs: Utilize PowerShell to search for audit logs related to mailbox permission changes:
Search-MailboxAuditLog -StartDate <StartDate> -EndDate <EndDate> -Operations <Operations> -Mailboxes <MailboxIdentity>Replace<StartDate>,<EndDate>,<Operations>, and<MailboxIdentity>with the appropriate values for your search.
Set up Alerts and Notifications
Proactively monitoring mailbox permission changes involves setting up alerts and notifications for immediate awareness of any unauthorized or suspicious activity.
- Configure Alert Policies: In the Microsoft 365 Security & Compliance Center, create alert policies to notify you when specific mailbox permission changes occur.
- Define Alert Criteria: Define criteria such as the type of action (e.g., permissions changed), specific mailboxes, and threshold conditions that trigger an alert.
- Select Notification Methods: Choose how you want to be notified, such as via email, text messages, or through a security information and event management (SIEM) system.
Regularly Review and Analyze Logs
Establish a regular schedule to review mailbox audit logs and analyze any detected mailbox permission changes.
- Review Audit Logs: Regularly review the mailbox audit logs to identify any suspicious or unauthorized mailbox permission changes.
- Investigate Anomalies: Investigate any detected anomalies promptly to determine the cause and take appropriate action.
- Document and Report Findings: Document the findings of your audit reviews and generate reports to track changes over time. Use this data to enhance security measures and compliance protocols.
Conclusion
Detecting mailbox permission changes in Exchange Online is vital for maintaining a secure email environment, ensuring compliance with regulations, and safeguarding sensitive information. By enabling mailbox audit logging, utilizing PowerShell for advanced monitoring, setting up alerts, and regularly reviewing audit logs, you can effectively detect and respond to any unauthorized mailbox permission changes, enhancing the overall security of your organization’s email infrastructure.