The attachment icon next to the name does not reflect the file content-type when attaching a file without an extensionDescriptionFile attachments via inbound REST do not reflect the Content-Type for all file types when file extension is not used. When attaching files to a form, the icon that appears next to the name of the file may not relate/display as it should, showing a blank page, rather than the application icon. Steps to Reproduce 1. Find the sys_id of a record.2. In a REST message API, such as Postman, do a POST to /api/now/attachment/file?table_name=<table_name>&table_sys_id=<record_sys_id>&file_name=mysupportNOTE: The file name, mysupport, as saved on the instance does not include the file extension.3. Add Authorization information.4. In the Headers, add Content-Type application/vnd.openxmlformats-officedocument.wordprocessingml.document5. In the Body tab, select binary.6. Click Choose Files.7. Find and select a .docx file.Supplying the correct Content-Type is not reflected in the file attached to the record, which does not show the .docx file type.This is reproducible for the following file types and their corresponding Content-Types:Extension Content-Type.doc application/msword.docx application/vnd.openxmlformats-officedocument.wordprocessingml.document.xlsx application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.pptx application/vnd.openxmlformats-officedocument.presentationml.presentationCompare with the following file types and Content-Types that work as expected:.xls application/vnd.ms-excel.ppt application/vnd.ms-powerpoint.pdf application/pdfWorkaroundThis is expected behaviour. To have the proper icons show up on the form, the icon image path needs to be mapped to the correct mime type on the [sys_attachment_icon_rule] table. For each file type that does not correctly display the icon on the form page, insert a record into sys_attachment_icon_rule with the correct mime type and path to the icon.Related Problem: PRB1356420