Client Side: A user or hacker uses the Client Side of the Trojan to control infected machines. It asks for the IP address or the ICQ number of the infected machine, and it connects to it at once.

Server Side: It is usually distributed on IRC. When a user joins a chat channel, the infected channel BOT automatically sends the Server file (it could be in different filenames) to the user.
    When the Server file is executed in the Victims' machine, it does not show any screen at all, It installs itself on the system. Then creates a copy of itself but with a new file named MSREXE.EXE in the C:\WINDOWS directory, It is loaded so that the Client side can remotely connect to the infected system.
    Then it adds the line Run=MSREXE.EXE in the [WINDOWS] section of the WIN.INI file so that it is loaded upon every Start-up.

    When it has been installed in the a system, a hacker using the CLIENT side can directly connect to the infected system and can do everything on it, such as:
File Accessing
Windows Shutdown
Restart
Mouse Control and etc.

To remove
The file MSREXE.EXE should be deleted and all entries added on the WIN.INI file by it should also be removed.