Among the many security topics to be discussed and revealed is the ability to compromise a Mac computer and leave without any trace or evidence. These kinds of attacks are routinely fought on Windows platforms and in the near future may begin showing up on Apple’s front. Because of the increase of Apple’s presence in the marketplace, the once secure OS will soon become a new haven of exploits and attacks. It’s sad to say but in the end, Mac users will pay for Apple’s success.

From technologyreview.com

“a student at the Politecnico di Milano, in Italy, explains that the technique allows an attacker to break into a machine without leaving a trace in its permanent memory, which means that evidence of the attack will disappear as soon as the victim's computer is turned off. Such a technique could be used, for example, in combination with another software flaw to covertly replace a legitimate version of Apple's Safari Web browser with a malicious one that logs the user's keystrokes and sends them to the attacker.”

“Attackers haven't focused much on the Mac to date because its smaller audience means smaller potential gains. But Dai Zovi notes that this is starting to change, and he says that researching the system's vulnerabilities now should give defenders time to prepare for future malware.”
“In the meantime, Iozzo says that users can protect themselves by keeping their systems up to date with any security patches released for OS X. Since the technique relies on other flaws that an attacker might exploit, users should focus on reducing those other threats as much as possible, he says.”
“However, the technique could soon pose a threat to another kind of device. Iozzo says that he is currently working with another security researcher to extend his technique to the iPhone.”

Source