A tweet from
reveals a denial of service attack knocked Battle.net and
Blizzard online services out: "We're currently investigating an issue affecting
our authentication servers, which may result in failed or slow login attempts."
Perhaps this was someone taking advantage of
that support is short staffed for the holidays. In any event, things
seem to be cleared up now, as
on the topic says:
The DDOS attacks that we were monitoring have
ended. If you are still unable to log in try
Troubleshooting - Blizzard Support.