With Mac sales up, and many new users coming to the platform, will malware writers begin to seek fresh targets? I asked the chief technologists at security companies Intego and McAfee what they saw as the primary threats to the Mac platform, both today and looking ahead.

While both agreed that Mac OS X is solid when it comes to security, they also fear that malware attacks on the Mac are inevitable—it's just a matter of when.

According to George Heron, the chief scientist at McAfee, 35% of the malware currently threatening computer users has been discovered in the past two years. In 2002, there were about 100 new detections a week. By 2007, that number had skyrocketed to 2000-plus. That's probably because the profile of cyber-criminals has changed. It's not about impressing your fellow geeks with your virus-writing prowess anymore. Today, money rules in the cyber-underworld, with malware going after financial information, credit cards, and bank accounts. Large, well-organized, highly sophisticated hackers design spam and phishing scams on a massive scale, largely operating out of China, Brazil, Russia, and the Middle East, according to Heron. More Macs in the marketplace means a growing profit opportunity in a highly profitable industry that steals billions worldwide.

Intego's Jack Nahan told me that the biggest threats to Mac users going forward are phishing, trojans, and ID theft. The two most interesting and insidious to date have been a scam where the user is invited to download a supposedly friendly new piece of anti-virus shareware called "Macsweeper" (it installs a trojan), and a "screen scraper" app that comes off the Web and never resides locally. It just copies whatever is on the user's screen (including banking information) and returns it to the scammer.

For more information on how to protect your computer (Mac or PC) and your information while online, check out these free resources on ConsumerReports.org:

• Cyber-security Central
• Best ways to stay safe online
• Best security software

And if you subscribe to ConsumerReports.org, you'll have access to:

• CR's latest Ratings of security software suites
• CR's latest Ratings of antivirus software
• CR's latest Ratings of antispyware software
• CR's latest Ratings of antispam software

—Thomas A. Olson