Princeton professor Andrew Appel decided to hack into a voting machine. He bought one online. Appel parted with $82 and became the owner of ...the Sequoia AVC Advantage, one of the oldest and vulnerable, electronic voting machines in the United States. He summoned a graduate student named Alex Halderman, who could pick the machine's lock in seven seconds. Clutching a screwdriver, [Appel then] deftly wedged out the four ROM chips - they weren't soldered into the circuit board, as sense might dictate - making it simple to replace them with one of his own: A version of modified firmware that could throw off the machine's results, subtly altering the tally of votes, never to betray a hint to the voter. The attack was concluded in minutes. Elections could be vulnerable at myriad strike points, among them the software that aggregates the precinct vote totals, and the voter registration rolls that are increasingly digitized. But the threat, the cyber experts say, starts with the machines that tally the votes and crucially keep a record of them - or, in some cases, don't. It's not just the voting machines themselves - it's the desktop and laptop computers that election officials use. And the computers that aggregate the results together from all of the optical scans. If any of those get hacked, it could could significantly disrupt the election. Hackers this year have [already] targeted voter registration rolls in Illinois and possibly Arizona, another attack highlighted by the Princeton alums.