You may have read in the press recently about the Mac Defender scareware that is affecting many OSX users, to the extent that Apple have even promised to deliver a removal tool and a fix to their customers. You may be surprised to hear though that Mac Defender is not the first “scareware” application targeting Mac users and trying to trick them into parting with their cash and their credit card details.

Malware for Mac OSX is nothing new, and the increasing popularity of the platform is driving criminal interest. In addition to Mac Defender (May 2011), there are already several threats in the wild that affect Mac OS X, the Leap worm (Feb 2006) that propagates through iChat , the RSPlug Trojan (Oct 2007), that drops DNS changing malware, the MacSweeper & IMunizator (Jan & Mar 2008) scareware, Jahlav (Dec 2008) another DNS changing malware, Krowi (Jan 2009) responsible for the first Mac OS botnet and HellRTS (April 2010) another Trojanised installer, this time for iPhoto which gives attackers remote control over the infected computer.

MacSweeper, IMunizator and now Mac Defender are typical scareware Trojans. In 2008 they were delivered by malicious advertisements and in 2011 criminals have adopted the tried and tested tactics so successful in the world of Windows, Blackhat Search Engine Optimisation. Booby trapped web pages are created, designed to show up in the first page of search results for popular terms. Simply clicking the link to one of these pages is enough to start the infection process.

The latest version has even worked out a method to bypass the requirement for the user to type an admin password in order to install. Affected users are presented with a professional look application and informed that multiple security issues have been discovered on their computer. Subsequently they are duped into buying a completely bogus piece of software to “fix” those issues, a tactic with which Windows users will be only too familiar.

RSPlug and Jahlav have both been known to pose as video codec installers, another tactic long popular on the windows platform. Once installed, DNS changing malware hijacks connections to sites such as eBay, PayPal and some banking sites. Often the malicious hosting site will distinguish whether the browser is Mac or PC based and serve up the correct flavour of Trojan demonstrating that it is the same skilled and experienced malware business that is now setting its sights on the Apple community.

It is also worth nothing that Mac Forums were subjected to a barrage of spam encouraging people to visit the hosting sites in what appeared to be a co-ordinated campaign. Also important is the fact that these malware examples are not single discrete files, they represent entire families of malware, where new variants are continually being released to defeat signature based detection.

These examples of techniques long tried and tested in the Wintel world should serve as a salutary warning to the Mac community, and it seems that Apple themselves may finally be listening. Malware has existed on the Mac platform since pre OS X days, as have anti-malware tools. However the radical change in the nature of the malware industry coupled with Apple’s huge success in recent years, means it is a trend which is now far more likely to be exploited for malicious ends and at the financial cost of the end user in the coming months and years.

For many years now Mac users have believed themselves to be invulnerable to malware, and have been encouraged in this belief by Apple themselves on more than one occasion, or ”Safeguard your data by doing nothing“.

This complacency leaves many Mac users with the mistaken belief that either Macs are not vulnerable to malware, or that none exists for their platform or both, impacting their ability to make informed decisions when downloading or installing new software, opening attachments or visiting questionable sites.

Cybercrime and malware in today’s world is big business, and one that ever more closely resembles the world of legitimate business, including outsourcing, R&D budgets, Malware as a Service platforms, SLAs and even EULAs. In this shady world of business it would defintely be fair to say that as the Mac market share expands and the user base grows, so does its perceived potential to the cybercriminal. It’s all about Return on Investment, and the fact that that user base is largely unprepared and the computers themselves largely unprotected only increases the attractiveness.