https://www.bleepingcomputer.com/news/security/microsoft-teams-bug-allows-malware-delivery-from-external-accounts/

Security researchers have found a simple way to deliver malware to an organization with Microsoft Teams, despite restrictions in the application for files from external sources.

With 280 million monthly active users, Microsoft Teams has been adopted by organizations as a communication and collaboration platform part of the Microsoft 365 cloud-based services.