: Used to find financial spreadsheets.

The search query filetype:xls inurl:"email.xls" is a classic example of a (advanced search operator). This specific string is used by security researchers and OSINT (Open Source Intelligence) practitioners to find publicly indexed Excel spreadsheets that likely contain lists of email addresses. Breakdown of the Query

With this one file, an attacker doesn't need to hack the firewall; they just walk through the front door using the credentials listed in row 14.