File types must be configured to provide mismatch warnings

From Microsoft Excel 2013 STIG

Part of DTOO143 - Force File Extension to match type

SV-53811r1_rule File types must be configured to provide mismatch warnings

Vulnerability discussion

Excel can load files with extensions that do not match the files' type. For example, if a comma-separated values (CSV) file named example.csv is renamed example.xls, Excel can properly load it as a CSV file.Some attacks target specific file formats. If Excel is allowed to load files with extensions that do not match their file types, a malicious individual can deceive users into loading dangerous files that have incorrect extensions.By default, if users attempt to open files with the wrong extension, Excel opens the file and displays a warning that the file type is not what Excel expected.

Check content

Fix text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Excel 2013 -> Excel Options -> Security "Force file extension to match file type" to "Enabled (Allow different, but warn)".

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