A new tool that can detect the Flashback Trojan on Mac computers has been developed and is available online for free. The Flashback malware is reported to have infected more than a half a million Mac computers.

The tool was developed by Juan Lean, a programmer at Garmin International, according to PCWorld. It can be downloaded from Github and works on the Mac OS X 10.5 and up. When run, it will either say that the program has found “No signs of infection” or provide further information. F-Secure has posted removal instructions on their site here.

The Flashback trojan takes advantage of a vulnerability in unpatched versions of Java in OS X. It poses as a browser plugin and may allow attackers to access personal information and passwords stored or used on the computer. Apple has released an update to fix the vulnerability in Mac OS X 10.6 and OS X Lion that have java installed. cNet has posted instructions on protecting prior Mac versions, as it appears that Apple will not be providing a fix for them, as they no longer support earlier versions.