That has changed to some extent, Mehl says. For example, it was recently discovered that rigged PDFs could exploit a security hole in Adobe Flash, a popular software component. The problem affects both Windows and Mac OS (Operating System) machines. Users are advised to keep not just the operating system and virus scanners current, but also programmes like Flash or Firefox.

'There is still less malware for the Mac,' Mehl says. Yet more and more people are working with the Mac OS and turning up vulnerabilities that have not yet been exploited. The threat potential has grown. 'That's why I feel that protection software is now important on Mac OS as well,' says Mehl.

Apple claims that the Mac uses integrated technology to fight off malware. Yet since no system is 100 percent immune from attacks, anti-virus software provides a supplemental layer of protection. Macwelt magazine sees two usable security programmes for Mac OS: Norton Internet Security for Mac from Symantec and VirusBarrier from Intego.

Installing anti-virus software is just part of the battle, Candid Wuest says. 'No matter which OS you use, you need to be constantly mindful.' Phishing attacks, where criminals try to trick users into divulging passwords or other data, affect Mac users just as much as Windows or Linux users. That means that users should think twice before clicking unsolicited links - be it via e-mail, Twitter, or any other delivery method the internet can provide.