Threat Protection and Copilot: Detecting Risks

Overview

Security teams often ask: “Does Copilot introduce new threats?”

The answer is nuanced. Copilot doesn’t necessarily introduce new vulnerabilities, but it acts as an accelerator. If a bad actor compromises an account, Copilot makes them faster at finding sensitive data. If an insider decides to exfiltrate data, Copilot makes them more efficient at summarizing it.

This video breaks down the threat model for Copilot, explains how your existing Microsoft Defender tools apply, and gives you a validation plan for your SOC pilot.

What You’ll Learn

• The three core threat scenarios: compromised user, malicious insider, and data exposure
• Why identity protection is your first line of defense for AI
• How to investigate Copilot activity using Unified Audit Logging
• A practical checklist for validating threat detections in your pilot

Script

Hook: Copilot doesn’t create threats—compromised identity does

If an attacker compromises a user today, they have to search through emails, open files, and figure out what’s valuable. It takes time.

If an attacker compromises a user with Copilot, they can just ask: “Summarize the most confidential projects from last month” or “Find all files mentioning ‘budget cuts’.”

Copilot makes a compromised account more productive.

So the threat question isn’t just “Is the AI safe?” It is: “Do we have strong enough identity controls to prevent the compromise in the first place?”

Threat model: the three scenarios to plan for

When we model threats for Copilot, we look at three main scenarios.

Scenario A is the Compromised User. This is what we just described. An external attacker gets a foothold. Copilot becomes a discovery tool for them.

Scenario B is the Risky Insider. This is a legitimate user who decides to do something bad—like taking data to a competitor—or simply does something negligent. They might use Copilot to gather data in bulk.

Scenario C is Data Exposure via Oversharing. This isn’t malicious—it’s accidental. Copilot surfaces sensitive content that was technically accessible to everyone (like a “Public” team site) but had remained obscure until now.

Notice the pattern? Copilot is permission-trimmed. It only shows what the user can see. So your threat posture still starts with identity and permissions.

Where Defender fits: protect the underlying workloads

You don’t need a separate “Copilot Defender” tool. You need to protect the workloads Copilot uses.

Copilot grounds on your data in Exchange, SharePoint, and Teams. So your existing Defender stack is still your primary defense.

• Microsoft Defender for Identity detects the compromised credentials and lateral movement.
• Defender for Office 365 catches the phishing email that leads to the compromise.
• Defender for Cloud Apps watches for mass downloads or unusual file activity.

From a SOC perspective, you don’t hunt “inside Copilot” in isolation. You hunt for abnormal access and sharing patterns across the Microsoft 365 environment. If you see an identity alert, assume Copilot could be used to accelerate the next stage of the attack.

Copilot-specific signals and investigations

What about logging?

Copilot activity is captured in the Unified Audit Log.

You can see when a user interacts with Copilot, and often what the context was.

In an investigation, you would correlate these events. Start with the identity alert. Then check the audit log: Did this user interact with Copilot immediately after the suspicious sign-in? Did they ask for summaries of sensitive data? Then pivot to SharePoint logs: Did they download the files Copilot referenced?

For our government customers in GCC, GCC High, and DoD: Make sure you verify your SIEM pipeline. Confirm that these new Copilot audit events are being forwarded to your SIEM and that you are retaining them long enough for an investigation.

Pilot validation checklist for the SOC

If you are running a pilot, don’t just test features. Test your security ops.

Here is a quick checklist for your SOC:

1. Validate Identity Controls: Ensure Conditional Access and MFA are strictly enforced for all pilot users.
2. Test DLP: Try to make Copilot summarize a document that has a sensitive label. Confirm that the summary respects the label’s protections.
3. Check the Logs: Have a pilot user run a specific set of queries, then go into the audit log and find them. Prove you can reconstruct the session.
4. Simulate a Threat: Have a red team member try to find “sensitive” (but fake) data using Copilot to see if your monitoring alerts on the rapid access.

Close: what success looks like

Threat protection for Copilot is really threat protection for Microsoft 365.

It requires tight identity controls, good permissions hygiene, and strong monitoring.

Copilot changes the speed of abuse, so your job is to ensure your detection and response capabilities can keep up.

Next up, we’ll look at DLP (Data Loss Prevention) and how to stop sensitive data from leaving the building.

Sources & References

• Security for Microsoft 365 Copilot — Overview of Copilot security model, service boundary, and protection stack
• Learn about Data Loss Prevention and Copilot — How DLP interacts with Copilot to prevent data exfiltration
• Audit logs for Copilot — Details on which Copilot interactions are logged and how to search them