Analysts in the company's labs have seen more financially motivated malicious software for OS X, Cluley said. Last week, the company spotted "OSX/Jahlav-A," a Trojan downloader.
Jahlav is often planted on Web sites as a purported key generator that can be used to figure out valid product codes for hacked software. But if it is installed, a hacker has complete control over the Apple computer and can download other bad software to the machine to steal data, Cluley said.
Businesses that handle credit-card data using Apple computers may also be required to use anti-virus software as part of recent security guidelines adopted by the payment card industry, Cluley said.
Additionally, Apple is now using Intel chips in its machines, which means some users may be using virtualization programs to also run Windows. Although the operating systems would run separately and can't infect each other, it could increase the likelihood of an Apple user passing along Windows files that are infected to another person in the office, Cluley said.
Malicious software is "nowhere like as big of a problem as on Windows but it does exist," Cluley said. "You can still get hit by it."