What Is a Zero-Click Vulnerability?
Eema Batool
Information Security Professional | IT Incident Management | GRC Analyst | IT/IS Process Improvement | ISO 27001 (ISMS) | 23001 (BCP) | ITSM | MS (Computer Networks & Security)
A zero-click vulnerability is an exploit that requires no user interaction. Unlike phishing (which needs you to click) or malware (which often needs you to download something), zero-click attacks silently exploit flaws in how software processes data, often via background tasks, preview functions, or API calls.
In this case, it’s about how Microsoft 365 Copilot accesses and presents data from services like Outlook, SharePoint, and Teams.
How Does the Attack Work?
AI tools like Copilot are trained to fetch and summarize data from across your Microsoft environment. The vulnerability here involved a failure in access control validation, allowing attackers to craft prompts or API calls that tricked Copilot into exposing data they shouldn't see.
No phishing. No compromised account. Just an AI doing what it's told, but told by the wrong person, under the wrong assumptions.
Think of it like this:
It’s like asking a personal assistant, “Can you read me Ema's emails?” And instead of saying, “You don’t have access,” they just start reading. Because the system never checked who was asking.
Who’s at Risk?
Organizations using Microsoft 365 with Copilot
Teams sharing sensitive content via Outlook, SharePoint, Teams
Users with elevated privileges or shared inboxes
Anyone using AI tools integrated into enterprise systems
What’s the Risk?
Exposure of sensitive or regulated data (e.g., financials, legal docs, employee info)
Data exfiltration without detection
Compliance violations (GDPR, HIPAA, etc.)
Loss of trust in AI-enabled productivity tools
How to Prevent It
Audit AI Permissions: Review what data Copilot can access and who is allowed to use it.
Apply Least Privilege Principles: Ensure users (and AI tools) only access what they absolutely need.
Isolate Sensitive Data: Use labeling, encryption, and DLP policies to keep confidential info out of AI reach unless intended.
Monitor Usage Logs: Track how AI tools are being used, especially if they're pulling unexpected content.
Educate Employees: Help users understand that just because Copilot can fetch something doesn’t mean it should.
Final Thought
The tools that make us more productive also open new doors for attackers. AI is powerful; but without proper boundaries, it can become an unintentional insider threat.
No click doesn’t mean no risk. Stay vigilant, audit your systems, and make sure your AI assistants serve you; not your adversaries.