I would like to assume the answer is no, but it bears asking.

I just discovered that someone has systematically gone through every question I've asked on drupal.stackexchange.com, and every answer I've given (or very nearly every one) and down-voted them. In the course of 12 minutes yesterday there are 34 down-votes in a row: clearly this is either a bug in the system (very unlikely), or an attack.

Is this okay to do? Can moderators do anything about such abuses?