Flashback harvests users' information like usernames, passwords, and other data. The first version of Flashback came inside a modified Adobe Flash installer, while the latest version pretended to be a Software Update prompt. By exploiting a Java vulnerability, this malware accessed the user's Mac computer when they clicked into a malicious link.

Intego discovered Flashback malware in September 2011, and so far, it has 14 variants.

Both malicious programs planted backdoors into Mac computers, allowing hackers to access without passwords. Hellrts was also another malware with the same function, packed in pirated versions of Apple iPhoto in 2010. Once installed, it connected to a specific remote server and waited for commands to action.

Krowi was malware that was packaged in most free and cracked versions of Apple iWork 2009 and Adobe Photoshop for Mac.

Once Leap installed, it recently infected opened Mac apps and made them unusable. It was discontinued in February 2012 and replaced by Messages. iChat is an instant messaging application that was first released by Apple in August 2002.

Leap was a Trojan-worm and used Apple iChat to spread in 2006.

Many dangerous Mac viruses and malware have been discovered in the past, which you might not know about yet, such as Leap, Flashback, Krowi, or Eleanor. But nothing is perfect, and there are still undiscovered security flaws that hackers may exploit. They are developing and adding many new features to fight against viruses and malware. I cannot deny that Apple was doing very well in the security field to protect macOS. Unfortunately, that is not entirely correct. These users do not really care about downloads and use any antivirus or internet security for Mac. The most common answer I received was: 'I have not even thought about that.', 'No computer virus on Mac.', or 'macOS isn't afraid of viruses or hacker attacks.' Many members consistently affirm that macOS is a closed system, and does not get viruses or any malicious programs. But the result that I got back was unexpected. Did you ever think viruses, malware, or adware would affect your Mac someday? It is a question I sent out to a group of normal Mac users a few weeks ago.

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