Detailed by Dr. Web, the trojan is a fake installer which can be downloaded from various sites under the guise of useful software.
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.
Apple quickly added the trojan to its "Xprotect.plist" blacklist which is updated daily and scans downloaded files to alert users of any threat.