Take note of this latest variation on malware.
A user received an email with the title – Message from “RNP0026735991E2″
The email had an Excel spreadsheet attached; the spreadsheet had a filename that is designed to look like a date. When viewed in the Outlook preview pane, it can be seen that the tabs are in Cyrillic script. Also, the file is in the old Excel spreadsheet format, with a file extension of .xls, rather than the newer .xlsx format. The file contains Macros (this cannot be seen in the Outlook preview pane though).
This appears a lot more convincing than a zipped file claiming to be an invoice, but we have little doubt that when opened this, it will infect your machine with malware. To re-iterate previous advice, if you receive an email that contains an attachment that you are not expecting, do not open the attachment and delete the email. If you receive an file claiming to be a Word document or Excel file, use the Outlook message attachment viewer to preview the file if you must view it, but best advice is to delete the email.