Mac OS X Java Trojan Horse: OSX/Koobface.A

Antivirus companies have discovered a new Java trojan horse, labeled OSX/Koobface.A (aka. Boonana), which spreads via social networks including Facebook, MySpace and Twitter. The Java applet masquerades as a video or photo gallery plugin, and requests access to the user’s computer.

If Allow is clicked, then the applet will attempt to obtain additional files from remote servers and join the computer to the Koobface botnet. Koobface is also known to try and steal credit card, and other personal information, from the user’s system.

I’d like to stress that this is a fairly non-event, and this kind of malware poses a low level of risk (hence the peaceful-looking blue triangle). It’s pretty clear that you shouldn’t allow websites, plugins and applets that you don’t trust, to access your computer. Just click Deny and that’s the end of it in this case. Snow Leopard does have some built-in anti-malware functionality, although I don’t know if or when it may be updated to detect Koobface. Either way, I wouldn’t run out to buy antivirus software just yet.

Note this trojan is not Mac OS X-specific, and also affects Windows and Linux systems.

Intego have a Security Memo with some additional details.