A new study performed by security firm Sophos has found that one in five Macs is likely to carry some sort of Windows malware, but only one in 36 could be infected with malware specifically designed to target Mac OS X. The numbers come after Sophos collected data from around 100,000 Macs that have the Sophos anti-virus software installed.
Of course, the Windows malware found on the Macs is harmless against OS X, simply lying dormant waiting to be deleted, but it’s a surprising figure nonetheless. That doesn’t mean that Mac users can’t be affected if they use Windows via Boot Camp, and they could potentially spread the malware using external storage.
As for the Mac malware, Sophos found that only 2.7% of the computers they scanned had malware designed to target OS X, and 75% of that is attributed to the recent Flashback trojan. If you recall, Flashback was a Java exploit spread via social networks designed to disable OS X’s anti-malware protections. There have been a couple of versions, and the latest manages cover its install tracks to avoid detection.
Apple released software that would allow users to remove Flashback, as have several anti-virus companies. The number of active infections has been dropping recently, but as of April 16th there were still around 142,000 Macs infected with the trojan.