Enlarge (credit: Jeremy Brooks / Flickr) Researchers have uncovered a never-before-seen backdoor written from scratch for systems running Windows, macOS, or Linux that remained undetected by virtually all malware scanning engines. Researchers from security firm Intezer said they discovered SysJoker—the name they gave the backdoor—on the Linux-based Webserver of a “leading educational institution.” As the researchers dug in, they found SysJoker versions for both Windows and macOS as well.