Two days after Mac OS X fake installer malware was discovered, Apple has updated its definitions to fight the malware, according to "MacRumors" (www.macrumors.com).

Earlier this week Russian anti-virus company Doctor Web told users (http://macte.ch/FflOH) about a new Trojan for Mac OS X dubbed Trojan.SMSSend.3666. The malicious scheme used to spread this Trojan is notorious among many Windows users, but until now it hasn't been employed to deceive owners of Macs, says Doctor Web. Trojan.SMSSend is a fake installer which can be downloaded from various sites under the guise of useful software.

Doctor Web says that Trojan.SMSSend programs are found in large numbers on the Internet. These are fake installers available on various sites disguised as distributions of legitimate software. When a user starts such an installer, they see the interface that imitates the installation wizard of a corresponding application.

In order to continue the "installation" fraudsters ask that the victim enter their cellphone number into an appropriate field and then specify the code found in a reply SMS. By performing these actions the user agrees to terms of a chargeable subscription and a fee will be debited from their mobile phone account on a regular basis.

Such installers usually contain meaningless data or the programs they are supposed to install, which in fact can be downloaded from official sites of their developers free of charge, notes Doctor Web. The take-away from all this: don't install software it it requires you to submit your phone number or send a text message.