Once relegated to Windows, the annoying adware known as Pirrit has now been ported to work on the Mac OS X operating system, and this variant is more malicious than its predecessor ever was, according to researchers at security firm Cybereason.

According to a Cybereason analysis report and corresponding blog post, Pirrit was converted to work on Macs using the Qt framework, which developers leverage to develop software capable of running on various platforms without substantially changing the code.

OSX.Pirrit has been deemed more dangerous than the Windows version because instead of just bombarding victims with ads, it also can take over one's machine. It's also much more difficult to eradicate because its removal instructions are buried inside the installation director, hidden from the user's view.

Cybereason has urged administrators to configure Macs to only run files that are code signed.