Researchers and cybersecurity professionals use these queries to find accidentally leaked data or to test a company's information exposure. If you find your own company's files using this method, it indicates that sensitive spreadsheets are being indexed by search engines
This operator restricts search results to a specific file extension. In this case, .xls (Microsoft Excel spreadsheets). Attackers love Excel files because they are the preferred format for businesses to store structured data: customer lists, payroll, inventory, and contact databases.