Hackers often exploit vulnerabilities in the code used to process older file formats (like Excel 95 workbooks or early Word documents) to execute malicious code. By default, Microsoft Office may block these outdated types to protect your computer from potential threats.
To understand File Block Settings, you have to understand the history of Office file formats. file block settings in the trust center
"If I unblock everything, my system is vulnerable." Reality: Unblocking .xls does not suddenly make you vulnerable to .xls malware if you have macros disabled and Protected View enabled. Security is layered. File Block Settings are one layer, not the whole wall. Hackers often exploit vulnerabilities in the code used
Use File Block Settings to enforce your file format policy , not to fix a one-off error. If a user complains they cannot open a .prn file from 1992, do not globally unblock .prn . Convert the file for them. Your security posture is only as strong as your oldest allowed file format. "If I unblock everything, my system is vulnerable
By default, when a file is blocked by these settings, the user gets a message and no option to override . However, older versions of Office (2010/2013) had a checkbox: "Do not show this message again and allow me to open."
If you are in IT support, you know the ticket. A senior executive tries to open a 15-year-old budget file. They see: