1 in 5 Macs is harbouring malware – for Windows

Many Mac users panicked earlier this month when the Flashback Trojan appeared, infecting about 600,000 Apple computers worldwide. But it looks like more Macs than previously believed could be carrying potentially harmful malware.

It just isn't going to hurt them.

A new study has shown that 1 in 5 Macs is harbouring malicious files, but those files will only do damage to Windows PCs.

Out of the 100,000 Mac computers that British anti-virus software maker Sophos analyzed, they found that 20% were carrying malware that could potentially harm a Windows computer, while only 2.7% (or 1 in 36) carried malware that could infect Mac OS X.

While Mac users may still be smug that they aren't going to be affected by most of the malware out there, they are still advised to be vigilant. If you run the Windows operating system on your Mac, as many Intel-based Macs are able to do, you open yourself up to previously non-threatening malware on your system.

Senior technology consultant Graham Cluley warns on Sophos' blog that Mac users need to be aware that they are a growing target.

"Sadly, cybercriminals view Macs as a soft target because their owners are less likely to be running anti-virus software," Cluely says. "Bad guys may also believe that Mac users are likely to have a higher level of disposable income than the typical Windows user. So, they might believe the potential for return is much higher."

Any Mac user hit by the Flashback Trojan knows all too well what a pain it is when you discover your computer is infected. Earlier this week, the origin of the trojan was traced back to a group of blogs on WordPress, MacWorld Australia reports. The number of infected blogs is estimated to be somewhere between 30,000 and 100,000, with 85 per cent of those based in the U.S.