Say hello to a network worm which attempts to compromise and spread through Windows machines with weak, default passwords. Called Deloder, the worm also tries to drop a backdoor component.
And yes the worm is spreading through vulnerable machines - albeit modestly, according to Symantec.
The worm spreads by scanning random IP addresses, trying to connect on Port 445. Port 445 (Microsoft SMB over TCP/IP) allows outsiders to access Windows file shares.
This should normally be blocked by a firewall, of course, so home users (or universities with weak security in place) are probably more at risk here.
If a successful connection is made, Deloder drops a called INST.EXE in the Windows Start folder. This is a Trojan designed to open a backdoor access to compromised computer.
Deloder then copies a file called DVLDR32.EXE, a copy of the worm itself, onto infected machines.
It then tries to obtain a list of computers connected to the same network and attempts to access them using default passwords, as explained in an advisory by Finnish AV specialist F-Secure.
Finally, Deloder disables shared network resources and places entries in the Windows Registry of compromised machines to make sure it is always run. This action has the side-effect of disabling network sharing.
AV vendors are in the process of updating signature definitions to detect the worm. As well as updating AV tools, users may want to check they're not using easily guessed or default passwords and to consider whether to disable network sharing.
You know it makes sense. ®