... From that last site...

"I've been sorta following this thread a little. Just wanted to comment that the rpcss.exe file is not as evil as everyone thinks and present a little insight from a practical view. it's more a case of it being "ill behaved". In most cases where there has been an incident with the rpcss.exe file it has come back to a case of configuration of networking in some manner. Proper configuration with an outdated file somewhere in the loop - forcing values into the TCP/IP setups for some cable users - dialup networking (for other ISP access) and ADSL software (winpoet) used on the same machine - inproperly configured router software in home networking sceinarios - and just plain old currupt files somewhere on the system - all these can cause problems that point to the rpcss file. rpcss.exe doesnt do anything until it interacts with some other part of the system. But anyway,,,rpcss is needed in some cases for proper functioning. It doesnt hurt to block it from getting out on the net for the most part because rpcss's activities take place on the machine , interacting with other components that do pass information on the net, but the rpcss file its self doesn't. even if your logs show something from rpcss.exe its not really from rpcss its from another item that sent information to rpcss and the rpcss.exe file just passed the information thru - think of it (when it acts this way) as a "mini switch" (not router) that simply directs the info where it wants to go.So yes in a way you could say that it does communicate to the network, and I think in some MS documentation it treats it in that manner.
This is a practical view. I have a whole thing on this from one of my MSCSE class mates but cant find it right now. And if memory serves me correctly we touched on its activity a little in Cisco router school a few years ago as it was just something that somehow came up in conversation while discussing OS interaction with Cisco products."

Jim