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A new cross-platform backdoor called “SysJoker” has been observed targeting machines running Windows, Linux, and macOS operating systems as part of an ongoing espionage campaign that’s believed to have been initiated during the second half of 2021.

“SysJoker masquerades as a system update and generates its [command-and-control server] by decoding a string retrieved from a text file hosted on Google Drive,” Intezer researchers Avigayil Mechtinger, Ryan Robinson, and Nicole Fishbein noted in a technical write-up publicizing their findings. “Based on victimology and malware’s behavior, we assess that SysJoker is after specific targets.”

The Israeli cybersecurity company, attributing the work to an advanced threat actor, said it first discovered evidence of the implant in December 2021 during an active attack against a Linux-based web server belonging to an unnamed educational institution.

images from Hacker News