Dino Dai Zovi, an independent security researcher who specializes in Macs, says that Iozzo's work is "very interesting," particularly given the difficulties that he needed to overcome to make the stealthy technique work on OS X.

Dai Zovi says that, for now, there are few Mac attacks sophisticated enough to need protection of this kind. But he adds that the technique could prove an effective way to get past advanced antivirus software in the future.

Attackers haven't focused much on the Mac to date because its smaller audience means smaller potential gains. But Dai Zovi notes that this is starting to change, and he says that researching the system's vulnerabilities now should give defenders time to prepare for future malware.

Iozzo says that it may take time for Apple to respond to his technique because it exploits fundamental elements of the operating system's structure that can't be changed with a simple software patch. He says that it may require a larger upgrade, such as the introduction of the new version of OS X, called Snow Leopard, which is scheduled to ship in 2010.

In the meantime, Iozzo says that users can protect themselves by keeping their systems up to date with any security patches released for OS X. Since the technique relies on other flaws that an attacker might exploit, users should focus on reducing those other threats as much as possible, he says.

However, the technique could soon pose a threat to another kind of device. Iozzo says that he is currently working with another security researcher to extend his technique to the iPhone.