Russian security vendor Kaspersky Lab has a prototype version of its virus protection software waiting in the wings in case Apple Mac OS X suddenly becomes a target of choice for hackers.

Kaspersky, based in Moscow, has no plans soon to make it into a product, but one could "be ready in just days," said Timur Tsoriev, spokesman, at the Cebit technology trade show in Germany on Tuesday.

[ Related stories: Apple growth will draw malware attacks and  PayPal warns: Steer clear of Apple's Safari browser ]

Kaspersky's anti-virus technology is flexible enough to work on different operating systems, said CEO Eugene Kaspersky. The company's analysts have also cracked open an iPhone, which runs a slimmed-down version of OS X, to see how it runs.

Whether to cover Apple's operating system has been a question for security vendors. At times, they've found it hard to make a business case to invest resources into building security software since Apple users feel segregated from the attacks suffered on a regular basis by Windows users.

As Apple's share of the PC market has grown, security analysts as well as vendors have forecasted that Apple's seeming immunity won't last forever.

So far, they've been pretty much wrong, as there have been no attacks on the scale that affects Windows machines, such as the Storm Worm. But Apple's software is far from perfect: In December, Apple issued 31 updates for Mac OS X. Its QuickTime multimedia player has also been patched several times.

As of now, hackers "don't pay any attention to the Mac at all," Kaspersky said. But it may come as no surprise that Kaspersky, whose business is based on selling security products, maintains he is skeptical of the security of most operating systems, including OS X.

"We see that Mac OS is taking a bigger and bigger share of the market," Kaspersky said. "We made the prototype to be ready just in case."

Net Applications, which tracks operating systems, said in January that OS X comprised about 7.6 percent of all of the PCs that visited a sampling of monitored Web sites. It was the third month in a row that the percentage increased.

Of security vendors with top market share, Symantec and McAfee have products for OS X, and Trend Micro secured a partnership last September to distribute software from Intego, which specializes in Mac Security products. Sophos, a company that focuses on the mostly-Windows corporate market, also supports the latest version of OS X, Leopard.

Finnish vendor F-Secure scuttled its Mac products around 1998, said Mikko Hypponen, chief research officer. But he didn't rule out the company taking another look at the platform. "Most of the hard-core geeks in our lab use Macs," he said.

Although Windows machines far outnumber Macs in businesses, it may be a good idea for administrators to run security software on a Mac if the machine is on a network with other Windows machines, said Marco Ruffer, who runs the business development section for Russian security company Dr. Web.

The Mac could potentially pass along harmful malware, even if it is not affected, he said. Dr. Web doesn't have a product for OS X, "but we've had some customers calling up" asking whether they offer it, Ruffer said.

Czech-based vendor AVG is also keeping an eye on how the Mac market shapes up. Miloslav Korenko, marketing director for AVG, said it's hard to say what level of Mac usage would prompt them to develop a product, "we are considering one as well."