A new worm called Morto has begun making the rounds on the Internet in the last couple of days, infecting machines via RDP (Remote Desktop Protocol) The worm is generating a large amount of outbound RDP traffic on networks that have infected machines. Morto is capable of compromising both servers and workstations running Windows. Users who have seen Morto infections are reporting in Windows help forums that are completely patched and are running clean installations of Windows Server 2003. Once it s on a new machine it scans the local network for other PCs and servers to infect.
Source: https://threatpost.com/new-worm-morto-using-rdp-infect-windows-pcs-082811/75585/