: Refrain from sharing files with sensitive information publicly. If a file must be shared, use secure, password-protected channels.
: This tells Google to only return results that are Excel spreadsheet files (.xls). filetype xls inurl password.xls
When combined, these operators target files that are named with the explicit purpose of storing passwords, which are often left unprotected on public-facing servers. The Risks of Exposed Spreadsheets : Refrain from sharing files with sensitive information