When Microsoft introduced Excel 2007, they introduced new file types – we all know them by now: xlsx, xlsm, xltx, etc. These file types are often referred to as Open XML. That's because the new file types are essentially packages that contain XML files. If you take an xlsx file and change the extension to zip, you'll be able to see all the xml documents that make up your Excel file.
The new Open XML file types come with lots of benefits. One of the major benefits is that you can change the content and properties of an Excel 2007 file simply by manipulating the XML documents that make it up.
Well, while playing with the Open XML files, I discovered that you can remove spreadsheet protection simply by applying a simple edit to the xml within the Excel file.
