Intego says it’s uncovered a Flashback Mac trojan horse that’s using “novel techniques to infect Macs.”

“Since then, we have discovered a number of samples of this latest variant, Flashback.G, and have seen evidence that many Mac users have been infected by this malware,” says Intego.

This new variant of the Flashback Trojan horse uses three methods to infect Macs. The malware first tries to install itself using one of two Java vulnerabilities. If this is successful, users will be infected with no intervention. If these vulnerabilities aren’t available — if the Macs have Java up to date — then it attempts a third method of installation, trying to fool users through a social engineering trick. The applet displays a self-signed certificate, claiming to be issued by Apple. Most users won’t understand what this means, and click on Continue to allow the installation to continue, says Intego.

For more info, including Intego’s recommended means of protection, go to .