A double extension file12is a file that displays two different extensions at once, one after another. Cybercriminals use double extensions to trick users into downloading and executing malicious files2. In a different context, the double extension method is used to obtain a price index from a representative sample of items in stock.
Cybercriminals use double extensions to trick internet users into downloading and executing a malicious file. They use familiar extensions like . docx or . pdf to hide the real extension of an executable file (like project.