In April, researchers at the Russian security vendor reported that Flashback had in Australia. This high penetration rate was attributed to two factors by Kaspersky Australia and New Zealand technical services manager, Nigel Hedges -- a lack of anti-virus security and Apple Australia's healthy market share of 11 per cent.

A total of 670,000 computers were infected worldwide with more than 98 per cent thought to be running Mac OS X. The United States had the most infected computers (300,917), followed by Canada (94,625), the United Kingdom (47,109) and Australia (41,600).

Kaspersky told Computerworld Australia that while the Flashback botnet had been a "wake up call" for Apple to improve security, the company still needed to improve some areas such as extending time frames for supporting older operating systems. For example, in May this year Apple for OS X 10.5, aka Leopard, when OS X 10.7, or Lion, was released.

"Apple has stopped supporting some older operating systems but there are still millions of people using these systems," he said. "It means if vulnerabilities are found, any kind of bad guys will be free to infect these machines."

In contrast, Microsoft has extended its support date for Windows XP, an operating system which dates back to 2001, until . "There are so many people around the world who still use XP and Microsoft are responsible for security," Kaspersky said.