Forget Prompt Injection: Your First Copilot Security Job Is Paying Off Years of Permission Debt

Hopefully you’ve noticed I avoid the accusatory tone in titles and subject but I caved this time because I think it’s actually pretty safe to assume the above statement does apply to all of us.

We each have to choose what to spend our attention on both organizationally and professionally. Often times it’s the old and boring problems promise more bang-for-the-buck and threaten more risk than the seductive cutting edge attack technique.

And wow if that isn’t true when it comes to M365 Copilot security.

We’ve been talking for years about permission drift, lack of least privileged, over-provisioned accounts, etc., etc. But except for short-lived and inconsistent efforts, at most organizations end user access is just something that grows and grows with time the longer the organization and employee stick around. And with the migration away from top down managed file servers to end-user managed Teams sites and M365 groups more and more responsibility for access control has steadily devolved upon endusers who want to get their job done a lot more than worrying about whether they are over-sharing. On top of that, the focus on privileged (admin) access at the system/control plane has greatly increase – which is great - but inevitably at the expense of end-user access to business data.

Permissive end-user access to business data is a serious instance of technical debt that I’ll specifically refer to as permission debt and it looks like M365 Copilot will be the bill collector.

Microsoft is at pains to point out that Copilot doesn’t pre-train on your organization’s data and when a given user prompts it, Copilot can only access what the user already has access to anyway. And that is factually accurate.

In this real training for free event, I’ll show you when and how Copilot accesses organization data as permitted by the user’s entitlements to respond to prompts. Instead of training the persistent model on your data, copilot dynamically searches organization data while observing the that particular user’s permissions to ground and inform the model’s response. Microsoft got a lot right with how they integrated the LLM and your organization’s data in order to deliver what we see as M365 Copilot and security thankfully in this instance at least was not an afterthought.

So if that’s true then what has changed to make end-user access suddenly more important?

The point is that Copilot doesn’t introduce new weaknesses – it industrializes the abuse of preexisting weaknesses that go back for decades. Copilot converts latent, tolerated security debt—overprovisioned accounts, overshared files, permissive SharePoint/Teams inheritance—into real-time, low-friction data exposure at machine speed.

And we’ll do some actual demonstration to prove the point.

Please join us for an exploration of:

• how M365 Copilot security works
• how it access your organizations data
• how it applies user permissions to limit it access with each prompt
• important features to help you limit the blast radius of how Copilot amplifies over-permissioning
• Restricted SharePoint Search (RSS): As a temporary measure, you can limit Copilot's search capabilities to a curated "allow-list" of up to 100 sites.
• Restricted Content Discovery (RCD): You can block specific high-risk sites entirely from being processed by Copilot, regardless of a user's permissions
• Sensitivity Labels - apply automated labeling and Data Loss Prevention (DLP) policies that specifically block Copilot from interacting with PII or other regulated data