Excel - Extension hardening
https://stackoverflow.com/questions/38529251/excel-does-not-prompt-for-incorrect-extension-extensionhardening https://blogs.msdn.microsoft.com/vsofficedeveloper/2008/03/11/excel-2007-extension-warning-on-opening-excel-workbook-from-a-web-site-2/ https://salesforce.stackexchange.com/questions/114584/warning-propmt-on-downloaded-excel-file-format-and-extension-do-not-match-the solution thru Registry edit: https://www.extracomm.com/Extracomm/FAQ.NSF/0/3ACF4AF056A7790848257AD400279396 coldfusion https://www.experts-exchange.com/questions/27027707/ColdFusion-to-Excel-a-solution-to-Extension-Hardening.html