Security Monitoring and Auditing for M365 Copilot

Overview

Security doesn’t stop at deployment—continuous monitoring is essential for detecting threats, ensuring compliance, and maintaining operational security. This video covers how to implement comprehensive security monitoring for Copilot using Microsoft Purview and integration with agency SIEM platforms.

Intended for security operations centers, compliance teams, and IT security administrators.

What You’ll Learn

• Audit Log Configuration: Enabling and accessing Copilot audit events
• Usage Monitoring: Tracking who uses Copilot, how, and for what purposes
• Anomaly Detection: Identifying unusual patterns that may indicate misuse or compromise
• SIEM Integration: Forwarding Copilot logs to Splunk, ArcSight, or other SIEM platforms
• Alert Configuration: Creating rules for security-relevant events

Transcript

[00:00 - Introduction]

Hi everyone, Sarah Johnson here. Today we’re diving into security monitoring and auditing for M365 Copilot. AI introduces new attack surfaces and usage patterns that require dedicated monitoring. Let’s explore how to gain visibility into Copilot activities and detect potential security issues.

[00:45 - Why Monitoring Matters for AI]

Copilot creates unique monitoring requirements:

Data access patterns: Users might inadvertently or maliciously use Copilot to access large volumes of sensitive data quickly. Prompt injection: Attackers could attempt to manipulate Copilot into revealing unauthorized information. Exfiltration risk: Copilot responses containing sensitive data could be copied to unauthorized locations. Policy violations: Users might violate acceptable use policies, requiring detection and response.

Traditional monitoring isn’t sufficient—you need AI-specific visibility.

[02:30 - Audit Log Architecture]

Microsoft 365 logs Copilot activities to the Unified Audit Log in Purview. Key event types include:

CopilotInteraction: Every prompt submitted and response generated. File access through Copilot: Documents referenced in generating responses. Copilot app usage: When users invoke Copilot in Word, Teams, Excel, etc. Sensitivity label application: When Copilot-generated content receives labels.

These logs are retained for 90 days by default, or up to one year with appropriate licensing.

[04:00 - Enabling Audit Logging]

First, ensure auditing is enabled. In the Microsoft Purview compliance portal, go to Audit, and verify that audit logging is turned on for your organization.

Next, ensure Copilot-specific events are being captured. This should be automatic, but verify by searching for CopilotInteraction events after deployment.

For long-term retention beyond one year, configure audit log retention policies in Purview. Government environments often require multi-year retention for compliance.

[06:00 - Querying Audit Logs]

You can search audit logs directly in the Purview portal. Navigate to Audit, select “Search,” and filter by:

Activities: Select “CopilotInteraction” or related events. Users: Investigate specific users if you have concerns. Date range: Narrow your search to relevant timeframes. Workload: Filter by specific M365 apps (Word, Teams, etc.).

Results show who used Copilot, when, what they asked, and what data was accessed.

[07:30 - Identifying Anomalous Behavior]

Look for patterns that may indicate security concerns:

Volume anomalies: A user suddenly making 10x more Copilot queries than normal. Off-hours usage: Copilot activity during unusual times or from unexpected locations. Sensitive data access: Copilot retrieving documents the user rarely accesses. Repeated similar prompts: Possible automated or scripted Copilot abuse.

Build baseline usage profiles so you can identify deviations.

[09:00 - SIEM Integration]

Most agencies have existing SIEM platforms—Splunk, ArcSight, QRadar, or others. Forward Copilot audit logs to your SIEM for centralized monitoring and correlation with other security events.

Use the Microsoft Graph API to programmatically retrieve audit logs and push them to your SIEM. Microsoft provides connectors for major SIEM platforms that include M365 audit log integration.

Once in your SIEM, create correlation rules. For example: “Alert if a user accesses 50+ documents via Copilot within an hour AND those documents are labeled as CUI.”

[10:45 - Creating Alerts]

Configure alerts for high-priority scenarios:

DLP policy violations involving Copilot-generated content. Copilot usage from risky or non-compliant devices. Attempts to use Copilot with highly classified or compartmented information. Unusual geographic locations for Copilot activity.

Alerts should go to your SOC for investigation and response.

[12:00 - Reporting and Compliance]

Generate regular reports for compliance and governance:

Monthly usage summaries: Total Copilot interactions, active users, most-used features. Security incident reports: Any Copilot-related security events or policy violations. Audit reports for ISSO/ISSM: Evidence of monitoring controls for authorization packages. Trend analysis: Usage growth, adoption rates, and emerging patterns.

These reports demonstrate due diligence to oversight bodies.

[12:45 - Conclusion]

Security monitoring for Copilot isn’t optional—it’s essential for maintaining your agency’s security posture and meeting compliance obligations. By enabling comprehensive audit logging, integrating with your SIEM, and creating targeted alerts, you gain the visibility needed to detect and respond to potential issues. Download our Audit Log Reference guide linked below for detailed event schemas and query examples.