Last month ESET researchers wrote an article about a new OS X malware called OSX/Keydnap, built to steal the content of OS X’s keychain and maintain a permanent backdoor. At that time of the analysis, it was unclear how victims were exposed to OSX/Keydnap. To quote the original article: “It could be through attachments in spam messages, downloads from untrusted websites or something else.”
During the last hours, OSX/Keydnap was distributed on a trusted website, which turned out to be “something else”. It spread via a recompiled version of the otherwise legitimate open source BitTorrent client application Transmission and distributed on their official website.