(Koichi Kamoshida/Bloomberg)

Mac users have always been a little bit smug when it comes to cybersecurity. Apple even brought up its product's resistance to viruses and malware in the famous line of Mac vs. PC commercials from the mid 2000s.  "You're lucky you don't have to deal with this stuff, Mac," John Hodgman's biohazard suit-clad PC tells a Mac played by Justin Long. 

But a new worm could end the myth of Max invincibility. The hack developed by researchers Xeno Kovah and Trammell Hudson can attack the firmware of Macs and all top PC makers, according to Wired. This malware was created not by hackers but by the researchers to show that it could be done.

Firmware is code that starts running as soon as a computer is turned on and starts to load its operating system. That makes the malware particularly hard to detect and fight: Even reinstalling an operating system could leave the worm nesting in the firmware, untouched.

The worm relies on a collection of firmware vulnerabilities that the researchers found in both PCs and Macs. More about the research will be revealed at a cybersecurity conference in Las Vegas later this week, according to Wired.

Wired also reported that the researchers notified Apple of the firmware vulnerabilities that affect Macs and that the company has patched some, but not all, of the issues. The worm will not work with the latest version of Apple software, according to a person with knowledge of the issue.

Apple declined to immediately comment on the report.

But this isn't the first time security vulnerabilities have affected Apple users. Last year  Apple admitted that its version of SSL, the encryption that protects much of online communications, had a flaw that could allow hackers to intercept and modify traffic thought to be secure. The problem affected both its mobile operating system iOS and its laptop and desktop suite OS X. And in earlier years, some OS X users fell prey to a Trojan malware known as Flashback.