Microsoft Bolsters Teams Security with Custom File Extension Controls

Microsoft is upgrading its Weaponizable File Protection feature within Teams to give admins more control over custom file extensions. This comes as an attractive environment for attackers has been noted in recent times, with Teams traffic often bypassing secure email gateways and benefiting from the perceived legitimacy of a colleague-initiated chat.

The automated part of the tool, which began rolling out in early 2026, scanned for potentially dangerous attachments. Now, admins can block certain file types to align with their organization's security requirements or use the Microsoft-recommended default list.

Microsoft aims to roll out this new feature by November 2026, allowing admins to customize which file types are blocked across the organization.