A recently discovered cybercrime gang, tracked as Epic Manchego, is using a new technique to create weaponized Excel files that are able to bypass security checks and that had low detection rates. The trick used by the Epic Macnchego gang consists of compiling the documents with a.NET library called EPPlus, instead of the standard Microsoft Office software. The EPPlus library is widely adopted by several organizations and development team that integrates it in their applications to add functions such as the Export as Excel or Save as spreadsheet”]
Source: https://securityaffairs.co/wordpress/107973/hacking/epic-manchego-excel-trick.html