Version 2.90 of the Transmission BitTorrent client came with an unwanted feature: the KeRanger ransomware, which may be the first bona fide ransomware for the Mac. Three days after being installed, KeRanger begins encrypting files, and affected users must pay a ransom of 1 Bitcoin (about $400) to get their files back. Thankfully, Apple and the Transmission developers worked quickly to mitigate the attack. Apple revoked the stolen certificate used by KeRanger, so it will no longer work on Macs protected by Gatekeeper, and the Transmission Project has updated Transmission to 2.92, which automatically removes KeRanger if it’s present. If you have Transmission installed, update it immediately, and if you’ve turned off Gatekeeper for any reason, turn it back on by going to System Preferences > Security & Privacy and selecting Mac App Store and Identified Developers under Allow Apps Downloaded From. And keep good backups! follow link
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