Critical Security Flaws in Microsoft Teams Enable Impersonation and Undetected Message Manipulation

Critical Security Flaws in Microsoft Teams Enable Impersonation and Undetected Message Manipulation

Cybersecurity researchers have identified four significant vulnerabilities in Microsoft Teams that could allow attackers to impersonate colleagues, alter messages without detection, and manipulate notifications to deceive users. These flaws, disclosed in March 2024 and addressed by Microsoft in August 2024 (CVE-2024-38197), September 2024, and October 2025, pose serious risks to organizations by undermining trust in the platform.

Key Vulnerabilities and Attack Vectors

• Impersonation and Spoofing:

  • Attackers could modify the sender’s name in messages or calls, making it appear as if high-profile executives or trusted colleagues sent them.
  • Impact: Enabled social engineering attacks, such as phishing or tricking users into sharing sensitive data.

• Undetected Message Edits:

  • Messages could be altered without the “Edited” label, leaving no trace of tampering.
  • Impact: Allowed attackers to change malicious content (e.g., links) post-sending, bypassing user scrutiny.

• Notification Manipulation:

  • Incoming notifications could be altered to display a forged sender identity, making malicious messages appear legitimate.
  • Impact: Increased the likelihood of users interacting with malicious payloads under false pretenses.

• Display Name Manipulation:

  • Attackers could change display names in private chats, call notifications, or during calls, forging caller identities.
  • Impact: Enabled impersonation in real-time communication, eroding trust in voice and video interactions.

Microsoft’s Response and Patch Timeline

• CVE-2024-38197:

  • Assigned a CVSS score of 6.5 (medium severity), affecting Teams for iOS.
  • Patches:
    • Initial fix in August 2024.
    • Subsequent updates in September 2024 and October 2025.

• Microsoft Advisory:

  • Highlighted the platform’s high value to cybercriminals and state-sponsored actors due to its global adoption.
  • Warned that features like messaging, calls, and screen-sharing are exploited at various stages of attacks.

Implications and Expert Perspectives

• Erosion of Digital Trust:

  • Oded Vanunu of Check Point emphasized that collaboration tools like Teams are now as critical as email but equally vulnerable.
  • Quote: “Threat actors don’t need to break in anymore; they just need to bend trust.”

• Risks to Organizations:

  • Attackers could exploit these flaws to gain remote access, deploy malware, or manipulate users into unintended actions (e.g., clicking malicious links).
  • Impact: Potential for data breaches, financial loss, and reputational damage.

Recommendations for Mitigation

• Update Systems: Ensure all Teams clients are patched with the latest updates (August 2024, September 2024, October 2025).
• Verify Sender Identity: Implement multi-factor authentication and verify suspicious messages through alternative channels.
• User Training: Educate employees on recognizing social engineering tactics and verifying high-risk communications.
• Monitor for Anomalies: Use security tools to detect unusual activity, such as frequent name changes or suspicious message edits.

For further details, refer to the original report:
https://thehackernews.com/2025/11/microsoft-teams-bugs-let-attackers.html