Security watchers warned on Friday that a new variant of a Mac-specific password-snatching Trojan horse is spreading in the wild.

Flashback-G initially attempts to install itself via one of two Java vulnerabilities. Failing that, the malicious applet displays a self-signed certificate (claiming to be from Apple) in the hope users just install the malware.

Once snugly in place, the malware attempts to capture the login credentials users enter on bank websites, PayPal, and many others.

OS X Lion does not come with Java preinstalled, so users of Mac's latest OS are less at risk of attack, but Snow Leopard does, and many users have not yet made the switch.

Mac security specialist Intego warns that the variant is infecting Mac users and spreading in the wild. Symptoms of infection can include the crashing of browsers and web applications, such as Safari and Skype.

Intego, which has added detection for the malware, has a write-up of the attack with a screenshot of the self-signed certificate used by the malware in action.

A report out this week from McAfee noted that after a spike of fake anti-virus packages targeting users back in June very little malware targeting Mac fans has been seen since. There were four million new strains of Windows malware in Q4 2011, compared to less than than 50 new Mac malware samples over the same three month period, according to McAfee. ®