MacOS malware
macOS malware includes viruses, trojan horses, worms and other types of malware that affect macOS, Apple's current operating system for Macintosh computers. macOS (previously Mac OS X and OS X) is said to rarely suffer malware or virus attacks, and has been considered less vulnerable than Windows. There is a frequent release of system software updates to resolve vulnerabilities. Utilities are also available to find and remove malware.

History
Early examples of macOS malware include Leap (discovered in 2006, also known as Oompa-Loompa) and RSPlug (discovered in 2007).

An application called MacSweeper (2009) misled users about malware threats in order to take their credit card details.

The trojan MacDefender (2011) used a similar tactic, combined with displaying popups.

In 2012, a worm known as Flashback appeared. Initially, it infected computers through fake Adobe Flash Player install prompts, but it later exploited a vulnerability in Java to install itself without user intervention. The malware forced Oracle and Apple to release bug fixes for Java to remove the vulnerability.

Bit9 and Carbon Black reported at the end of 2015 that Mac malware had been more prolific that year than ever before, including:
 Lamadai – Java vulnerability
 Appetite – Trojan horse targeting government organizations
 Coin Thief – Stole bitcoin login credentials through cracked Angry Birds applications

A trojan known as Keydnap first appeared in 2016, which placed a backdoor on victims' computers.

Adware is also a problem on the Mac, with software like Genieo, which was released in 2009, inserting ads into webpages and changing users' homepage and search engine.

Malware has also been spread on Macs through Microsoft Word macros.

Ransomware
In March 2016 Apple shut down the first ransomware attack targeted against Mac users, encrypting the user's confidential information. It was known as KeRanger. After completing the encryption process, KeRanger demanded that victims pay one bitcoin (about  at the time, about  as of February 18, 2021) for the user to recover their credentials.

References

 
Malware by platform