I reported that there is malware floating around that claims to be an update to the Adobe Flash Player. The variant initially discovered (OSX/Flashback.A) would install a backdoor on your system, allowing someone to access your files without your knowledge. A new variant has been found that not only installs the backdoor but also removes the ability to automatically detect it.
Back during the great MacDefender scare, Apple added the ability for OS X to detect malware and prevent it from being installed. Flashback.C will disable this feature, preventing your system from downloading updates to detect and remove it. It can be removed via malware scanners like Sophos and F-Secure.
Right away, people may question the security of an operating system that would permit this to happen. As I stated in the last article, these scams are targeting the user, not the OS. The OS is secure, but it still has to allow the user to maintain some level of control. If a user enters his or her password to install a rogue application, OS X will install it. It falls to the person using the system to decide what is and is not safe.