Despite the new threat, a leaked document suggests Apple is apparently refusing to offer support to affected users.
A widespread fake security antivirus called Mac Defender uses a scare-and install tactic that has been seen countless times in the world of Windows, but with Apple gaining ground as a mainstream platform the practice has spread to Macs.
A pop-up notifies the user that Defender has identified malware on the computer, and that they should download the security software to remove the code, Graham Cluley, senior technology consultant at security firm Sohpos, told PC Pro.
According to Cluley, downloading simply installs the malware, which then demands credit card details for a version that can remove the malware.
Apple's forums have a significant number of threads advising how to resolve the problem, but the company itself has come under fire for the lack of support given to customers, with reports claiming Apple has washed its hands of the problem, and refused to even admit that Mac Defender is malware.
A leaked support document apparently from Apple seemingly directs AppleCare workers not to "confirm or deny" whether a user's Mac is infect, and not to attempt to remove or uninstall any infections.
The document, leaked to ZDNet, tells support workers to stress that Apple doesn't provide "help or support for removal of the malware."
“It appears that Apple's official response is: 'we're not going to help you clean up',” said Cluley.
“It's saying [users] should go and get an antivirus program because it doesn't want to take on the burden – and in the last couple of weeks, from what we've read, it has seen a significant increase in malware.”
Apple has yet to respond to a request for comment.
Apple's OS has long been seen as a safer choice than Windows, mostly because it has fewer users and therefore presents less of a target.
According to Gartner figures, Apple has seen a surge in popularity, and now accounts for some 10% of sales in the key US market, making it a more attractive option for online criminals.
“Effectively it's reached a tipping point where people are not uncommonly getting hit on their Macs," said Cluley. "On the support forums you'll see plenty of people who say they were just Googling around when a message popped up and convinced them they had a security problem.”
“In terms of malware, it's the biggest event to date, there were earlier viruses and malware, but this is big,” he said of the Mac Defender threat.