VBA macros are a common and easy way for mal intended hackers to deploy malware and ransomware. To help improve security in Office apps, Microsoft is blocking macros by default in Office application files received from the internet. In this post, you will find the official information about this behavior and how to unlock VBA macros in files received from the internet.
As of the publishing date of this post, this change is already effective for users subscribed to the Office Insiders program and the change will be gradually applied to other versions of Office.
With this change, when users open a file that came from the internet, such as an email attachment, and that file contains macros, the message “Microsoft has blocked macros from running because the source of this file is untrusted” will be displayed: