THE computer security industry buzzed with warnings that more than a half-million Macintosh computers may have been infected with a virus targeting Apple machines.

Flashback Trojan malware tailored to slip past "Mac" defenses is a variation on viruses typically aimed at personal computers (PCs) powered by Microsoft's Windows operating systems.

The infections, spotted "in the wild" by Finland-based computer security firm F-Secure and then quantified by Russian anti-virus program vendor Dr. Web, come as hackers increasingly take aim at Apple computers.

"All the stuff the bad guys have learned for doing attacks in the PC world is now starting to transition to the Mac world," McAfee Labs director of threat intelligence Dave Marcus told AFP.

"Mac has said for a long time that they are not vulnerable to PC malware, which is true; they are vulnerable to Mac malware."

Dr. Web determined that more than 600,000 Mac computers may be infected with Flashback, which is designed to let hackers steal potentially valuable information such as passwords or financial account numbers.

Hackers trick Mac users into downloading the virus by disguising it as an update to Adobe Flash video viewing software.

Apple has long boasted that Windows machines are more prone to hacking than Macs.

Computer security specialists contend that the reason for the disparity was that since most of the world's computers were powered by Windows, hackers focused on systems that promised the most prey.

As the popularity of Macs has soared, so has the allure of hacking Apple operating systems, according to Marcus.

"There has been a significant increase in Mac malware in the last several quarters, so what we've seen with the Flashback Trojan isn't particularly surprising," Marcus said.

"Cybercriminals will attack any operating system with valuable information, and as the popularity of Macs increase, so will attacks on the Mac platform."

Computer users, no matter their operating systems of choice, need to protect machines with tactics including up-to-date anti-virus programs and avoiding risky habits such as opening files or clicking links from unknown sources.

gc/sst