What is Foop file (.Foop file extension) .Foop file extension is an extension that is associated with a new variant of dangerous ransomware called STOP (Djvu). Although ‘Foop’ variant was released recently, many users have already encountered a result of its malicious activity. It encrypts files located on the computer, and renames them adding .foop … Continue reading .Foop file extension. Remove Foop virus. Restore, Decrypt .foop files.