Though hackers target Macs far less frequently than Microsoft Windows PCs, doesn’t mean Mac users are in the clear by any means.

Antivirus firm SecureMac claims to have discovered multiple variants of a Trojan horse being distributed from a hacker Web site. The site hosts a discussion on distributing the Trojan horse through iChat and Limewire.

The Trojan distributed as either a compiled AppleScript called ASthtv05 or as an application bundle called AStht_v06, exploits a recently discovered vulnerability with the Apple Remote Desktop agent. The ARD allows the Trojan to run as root.

According to SecureMac, the Trojan runs hidden on a Mac and allows a malicious user complete remote access. The Trojan can transmit system and user passwords, and avoid detection by opening ports in the firewall and turning off system logging.

Mac users should be careful, and not download any suspicious games, video or utilities. Only download programs from a trusted source to avoid this exploit.