Even though instances of Mac malware remain rare, that’s no reason for complacency so say security specialist Sophos — and let’s face it they should know.

Sophos has detected a number of corrupt files, using their anti-malware scanner, which are capable of causing harm on MacBook or Apple PCs if the malicious content (only capable of infecting Windows boxes) is shared.

One specific threat — known as ASDFDldr-A comes in the form of media file that poses as music from the likes of Lady Gaga and Madonna.

The files uses the scripting capability of Microsoft Media Player to infect Windows machines and redirect users to a booby-trapped website instead of playing the media content users were hoping to enjoy.

How do Sophos know all this. Well their Mac malware data comes from the 150,000 active users of Sophos Anti-Virus for Mac Home Edition who have downloaded and updated the anti-malware software since its launch on 2 November.

The security software is among the top 10 most downloaded products from Apple’s download site and the most popular application from its networking and security section.

Sophos’ first free of charge anti-virus scanner, which was released earlier this month, also detected Javabased attacks which were found in the internet caches of Mac machines.

The security tool also found well-know Mac Trojans disguised as codecs supposedly needed to display video content on sites such as BitTorrent which are under the control of hackers.

Sophos also issued a warning that the infamous Conficker worm which can’t infect Macs but can be spread via USB drives. There is no obvious effects to Mac users except to make them carriers, which can spread onto previously uninfected Window’s boxes.

“There is much less Mac malware than Windows malware, but that doesn’t mean that Mac users should be blase about protecting their computers,” said Carole Theriault, senior security consultant at Sophos.