When Microsoft Teams Isn’t as Secure as You Think

How a new exploit puts chat data at risk

In a recent disclosure, researchers revealed a Beacon Object File (BOF) tool that can extract authentication cookies from Microsoft Teams without disrupting the application’s normal operation. Here’s a breakdown of how this works—and, more importantly, what your organization should do about it.

🔍 What’s the vulnerability?

• Microsoft Teams uses a Chromium-based embedded browser (via msedgewebview2.exe) for authentication and chat operations. The authentication cookies are stored in a SQLite database.

• Unlike hardened browsers that use stronger encryption mechanisms (COM-based services running at SYSTEM level), Teams relies on the DPAPI (Data Protection API) tied to the current user’s master key—making it comparatively easier to target.

• Attackers bypass file locks and normal protections by injecting into the ms-teams.exe process (or child web view processes), duplicating file handles to the cookie database, decrypting payloads, and ultimately gaining access to those cookies.

• Once the attacker has valid authentication tokens, they can impersonate users, fetch conversation histories, read/send messages, access Graph API calls, and potentially move laterally across an enterprise environment.
  

🧠 Why this is a big deal

Your organization may trust Microsoft Teams as the go-to collaboration platform—but this exploit shows how embedded browser components and seemingly benign productivity tools can become glaring weak spots.

• Chat history leaks = confidentiality compromised.

• Impersonation of users = trust eroded, phishing and social-engineering risk increases.

• Lateral movement possibility = one compromised user becomes the pivot for broader breach.

• The hybrid-work model (remote access, cloud apps, etc) amplifies the risk.
  

At Plexus IT, we understand that protecting your collaboration tools is just as important as securing your data centre. So here's what we can offer for your organization:

• Comprehensive endpoint-cloud coverage: We help you monitor suspicious process-injections and token manipulations across devices and cloud apps.

• Identity and access governance: We implement least-privilege models, enforce policy controls, and manage token-lifetime/refresh strategies.

• Managed detection & response (MDR): With our 24×7 monitoring, unusual Teams activity (e.g., impersonation, lateral movement) is flagged and acted upon—before it becomes a full-scale breach.

• User training & awareness: We provide modern phishing and impersonation awareness modules tailored for chat platforms like Teams, mitigating social-engineering risk.

• Proactive vulnerability management: With our scheduled reviews, we identify weak spots (like embedded browser components) and help you patch/configure ahead of attackers.

If you’d like to review your organization’s readiness for such threats, or ensure your Teams-environment is configured and monitored correctly—get in touch today for a free assessment of your collaboration security.