Is That Really Your Coworker on Teams? The Hidden Risks of Collaboration Tool Impersonation
Microsoft Teams has become the backbone of modern business communication, with more than 300 million users relying on it for everything from quick chats to boardroom decisions. But recent discoveries of four critical security flaws serve as a stark reminder: the person on the other side of your Teams chat may not be who you think they are.
The Vulnerabilities That Shook Trust
Security researchers uncovered flaws that—before being patched—allowed attackers to:
Impersonate colleagues or executives
Manipulate conversations and alter chat history
Exploit notifications to deliver deceptive alerts
Forge caller identities in audio and video calls
These weaknesses didn’t just affect external guest accounts. Even internal malicious actors could have blurred trust boundaries, tricking employees into clicking malicious links, oversharing sensitive data, or approving fraudulent requests.
In short, the very features that make Teams a powerful collaboration tool—messaging, calls, and screen sharing—were turned into potential weapons for deception.
Why This Matters for Businesses
The implications go far beyond technical bugs. Collaboration platforms run on trust. When that trust is undermined, attackers gain a direct line into decision-making processes, financial approvals, and sensitive conversations.
Imagine receiving what looks like an urgent message from your CFO:
“Approve this wire transfer immediately.”
“Share the client file before the meeting.”
If the message looks authentic, most employees won’t hesitate. That’s exactly why these flaws were so dangerous—they eroded the fundamental trust that makes digital collaboration possible.
Microsoft’s Response
Microsoft has since patched the vulnerabilities, closing the immediate loopholes. But the incident highlights a larger truth: patches fix code, not human behavior. Once trust is broken, it’s far harder to repair.
Lessons for Small Businesses
For small businesses, where Teams often doubles as the central hub for operations, the risks are amplified. Unlike large enterprises, smaller organizations may not have dedicated security teams monitoring for anomalies. That makes security awareness training and zero‑trust principles essential.
Here are three actionable steps every business should take:
Educate employees – Teach staff to verify unexpected requests, even if they appear to come from trusted colleagues.
Adopt zero‑trust practices – Don’t assume internal communications are inherently safe. Layer in verification and access controls.
Monitor for anomalies – Watch for unusual edits, impersonation attempts, or suspicious notifications.
The Bigger Picture: Trust Is the New Attack Surface
Attackers no longer need to “break in” to systems—they just need to bend trust. By manipulating what people see and believe, they bypass traditional defenses. Collaboration tools like Teams, Slack, and Zoom are now as critical as email—and just as exposed.
As I often remind clients: security isn’t just about protecting systems, it’s about protecting trust. Without trust, collaboration collapses.
Final Thoughts
The recent Teams vulnerabilities are a wake‑up call. Even the most widely used, enterprise‑grade platforms can become vectors for deception. The good news is that Microsoft has patched the flaws. The better news is that businesses can use this moment to strengthen their defenses, reinforce awareness, and remind employees that verification is the new default.
So next time you get that “urgent” Teams ping, pause for a second. Ask yourself: Is this really my colleague—or just their evil twin?
Take Action with Actionable Security
At Actionable Security, we know that email isn’t the only attack vector anymore—collaboration platforms like Teams are just as critical. That’s why our Email Security Assessments go beyond inboxes to evaluate how your business communicates across Teams and other tools.
Because protecting your people means protecting every channel they trust.
#WhoDisOnTeams #EvilTwinMeetings #TrustButVerify
