At the Black Hat security conference on Wednesday, security researcher Dino Dai Zovi revealed a proof-of-concept rootkit that runs on Apple's Mac OS X operating system, underscoring the fact that all software has flaws.

Rootkit software is designed to covertly run code, typically malicious, on affected systems. It can be used to steal information or control a compromised system. Rootkits are typically installed by other malware.

Apple users have enjoyed a relatively malware-free existence, at least compared to Windows users, and Apple has made much of that fact in its television commercials. But there are holes to be found in Apple's software, too. There just aren't a lot of cybercriminals focused on a platform that's less than 10% of the market.

That's been changing slowly, with the spread of the OS X-based iPhone, and the popularity of iTunes among Windows users. Security vendors, eager to sell Mac users security software, suggest the situation is changing quickly.

Thanks to the work of Dai Zovi, author of The Mac Hacker's Handbook, and other security researchers focused on the Mac, like Charlie Miller, the vulnerabilities in Apple's software are better understood. In theory, such work makes computer users safer by encouraging companies to fix disclosed vulnerabilities.

Apple did not respond to a query about whether it had patched its software to block Dai Zovi's attack.

Dai Zovi's proof-of-concept rootkit is called Machiavelli, a reference to the Mach kernel that underpins Mac OS X.

"Machiavelli consists of a Mach proxy server on the local controlling host and a number of remote agent servers that run on remote compromised hosts," Dai Zovi explains in a technical paper that describes his work. "On the controlling host, rootkit management utilities obtain a proxy Mach port from the proxy server and use it just as a normal application would use a local Mach port."

With his presentation complete, Dai Zovi plans soon to release several Mac software tools related to his research on his Web site. These include: Inject Bundle, for data injection; iChatSpy, code for logging instant messages; SSLSpy, for logging SSL traffic; iSightSpy, for capturing a single frame from any Apple iSight camera; Machiavelli, for remotely controlling a compromised system; and Uncloak, a rootkit identification tool.

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