"“There is a big possibility that you are part of the problem without even knowing it,” said Paul Vixie, chairman of the Internet Software Consortium, a nonprofit company responsible for the software used by many of the servers that power the Internet.
The servers the attackers used — what the Internet community calls open recursive servers or, more commonly, open resolvers — are simply home Internet devices, corporate servers, or virtual machines in the cloud that have been sloppily configured to accept messages from any device around the globe. [...]
But there is a silver lining. “I’ve been waiting for this attack for a long time,” Dr. Vixie said, “so that we could tell the earth’s population to do something about it.”"Devices Like Cable Boxes Figured in Internet Attack - NYTimes.com