Trojans are malicious applications that pose themselves as legitimate software in order to trick users to install them. Once on the victim's machine, it may run any number of malicious process to steal vital information or inflict damage to other software.
This trojan installs several files that are intented to look legitimate. Users should be cautious of sms_msn40.exe as well as any random filenames suddenly appearing in their running processes.
Other parts of this trojan include a CLISD in the BHO section of the registry as well as autostarters that start up the infection when the computer reboots.