Security firm Sophos announced Tuesday
that data collected from 100,000 Mac computers revealed that 20% of those computers were carrying at least one instance of malware. The catch is that the 20% figure applies to malware designed to target Windows computers, but is harmless to Mac OS X. Sophos's blog post went into more details. The data comes from a snapshot of the millions of Mac computers that downloaded Sophos's free anti-virus software. While the Windows malware stored on Mac computers won't affect Mac OS X installations, the malware could then be transmitted to Windows over computer networks. The data in Sophos's study showed that 2.7 percent of Macs, or 1 in 36, were infected with actual OS X malware.