According to Sophos, malware for Macs has been seen before, but until recently, organised criminal gangs have not felt the need to target Mac users when there are so many more poorly protected Windows PCs available.
However, late 2007 saw Mac malware not just being written by researchers demonstrating vulnerabilities or showing off to their peers, but by financially-motivated hackers who have recognised there is a viable and profitable market in infecting Macs alongside Windows PCs.
For example, many versions of the malicious OSX/RSPlug Trojan horse, first seen in November 2007, were planted on websites designed to infect surfing Apple Mac computers for the purposes of phishing and identity theft.
"No-one should underestimate the significance of financially-motivated malware arriving for Apple Macs at the end of 2007. Although Macs have a long way to go in the popularity stakes before they overtake PCs, particularly in the workplace, their increased attractiveness to consumers has proven irresistible to some criminal cybergangs," said Graham Cluley, senior technology consultant at Sophos.
"Mac users have for years prided themselves on making smarter decisions than their PC cousins - well, now's the chance to prove it. The Mac malware problem is currently tiny compared to the Windows one, so if enough Apple Mac users resist clicking on unsolicited weblinks or downloading unknown code from the web then there's a chance they could send a clear message to the hackers that it's not financially rewarding to target Macs. If they fail to properly defend themselves, however, there's a chance that more cybercriminals will decide it's worth their while to develop more malware for Mac during 2008."
According to Sophos, its experts are now discovering 6000 infected web pages every day - one every 14 seconds. 83% of these web pages actually belong to innocent companies and individuals, unaware that their sites have been hacked. Websites of all types, from those of antique dealers to ice cream manufacturers to wedding photographers have hosted malware on behalf of virus writers.
In addition to Mac computers, Sophos says its Security Threat Report 2008 revealed that the iPhone and iPod Touch connected to the Internet via Wi-Fi hotspots are now attracting the interest of cybercriminals
According to Sophos, the report revealed that the wider use of new mobile technologies and Wi-Fi enabled devices, like Apple's iPhone and iPod Touch, are opening up new vectors of attack for hackers. Flaws have been found in the mobile email program and Safari browser installed on such devices - but while uptake remains limited cybercriminals seeking large returns are unlikely to exploit these avenues on a major scale in the near future. However, as personal Wi-Fi devices grow in popularity, Sophos believes the risks will no doubt increase.
Sophos experts also note that the low cost ultra-mobile PCs, such as the popular Linux-based ASUS EEE laptop, are likely to gain the attention of the cyber underworld as sales continue to grow.
"The ultra-mobile ASUS EEE laptop, like many others, comes pre-installed with Unix, making it automatically immune to the vast majority of spyware and malware attacks," said Cluley. "However, it's still possible to lose money through phishing and identity theft on any device with an internet connection. As it becomes more common for people to use a Wi-Fi enabled device which carries personal information, the greater the temptation for hackers to take advantage with malware in the future."
While many Mac and Linux users are likely to take Sophos' findings and warnings with a grain of salt, with the Mac approaching 8% market share, it would appear to be simple economics for cybercriminals, who know that many Mac users don't use security packages, to target this lucrative new market.