This worm has some other variants also such as W32.Downadup, Win32.Conficker.A, W32.Downadup.A, Conficker.A, Net-Worm.Win32.Kido, etc. It infects other computers across a network by exploiting the Windows Server service (SVCHOST.EXE) vulnerability and also spreads through USB Drives, external hard drives and MP3 players. Moreover this worm constantly updates by downloading new versions of it onto infected machines and keeps itself memory resident and is difficult to cleanup.The worm infects - in computer that has no latest security updates, in shared systems with weak passwords, use of removable devices such as flash drive or external hard disk, in computers with open shares (e.g. corporate networks), etc.
To prevent the infection download and install urgent Security Update from Microsoft. If already have infected or not sure, download, scan and remove using any of the free tools described below.
5. Microsoft MSRT
6. Panda Security