How to steal an election by hacking the vote is an article at respected technical site Ars Technica by Jon Stokes. It's currently on the front page of
slashdot, so the site may be a little slow if you click through.
Jon Stokes has decided that the current arguments and anecdotes of security irregularities and vulnerabilities are too abstrat. They're not making an impact, and they haven't led to changes needed to ensure election security.
What if I told you that it would take only one person--one highly motivated, but only moderately skilled bad apple, with either authorized or unauthorized access to the right company's internal computer network--to steal a statewide election?
Okay, a lot of us here believe this is possible... Stokes rightly focuses in on what he calls Direct-Recording Electronic (DRE) voting machines, because they lack a paper audit trail to allow for verification of elections. Then he breaks vote fraud down into two categories: Retail and Wholesale. Retail vote fraud is the nickel and dime stuff that's gone on for a long time...stuff like dead people voting. Of course there are checks in the system to prevent these simple frauds, and its going to take a lot of dead people to reliably affect an election.
So, to seriously affect an election, wholesale fraud is necessary. You need to make vote totals fit your desired outcome. You need to affect how votes are recorded or tabulated. And as Stokes points out over the next few pages of his article, DRE machines and current practices introduce multiple points where the election process becomes vulnerable to fraud.
The article is well researched, with links to many different sources. Take a look!