A week after its debut, Mac OS X Lion operating system is already piling up a list of reported vulnerabilities. Days of a virus-free Mac are gone, PCMag.com reported.

Some Lion vulnerabilities are carry-overs from Snow Leopard, like the "Mac Defender" class of scareware that first surfaced in May.

Another newly identified OS X threat is Olyx backdoor, which appears to be a variant of Microsoft Windows-targeting malware that is simply been tweaked to go after Macs.

Researchers say the remote-controlled Trojan application resembles 2009's GhostNet malware, a threat to Windows-based PCs. And as with the various strains of Mac Defender, some of the most knowledgeable and quickest responses to this latest backdoor threat are coming from Apple's longtime rival Microsoft.

Another threat to Lion is a vulnerability that enables passwords to be recovered from Macs via Firewire's use of Direct Memory Access (DMA). Another is a laptop battery chip vulnerability that doesn't appear to have been addressed in any OS X 10.7 updates as of yet. Security researcher Charles Miller of Accuvant Labs says this vulnerability can be exploited to "brick" batteries in several Apple laptops.

Apple's success at gaining market share for OS X has clearly not come without a cost-whereas malware developers generally ignored Macs when they made up a fraction of the market, now they have every reason to target Apple.