“Ballot marking devices (BMDs) allow voters to select candidates on a computer kiosk, which prints a paper ballot that the voter can review before inserting it into a scanner to be tabulated.” “However, BMDs do not eliminate the risk of vote-stealing attacks. Malware could infect the ballot scanners and change the electronic tallies … or it could infect the BMDs themselves and alter what gets printed on the ballots. This latter variety of cheating cannot be detected by a post-election audit, since the paper trail itself would be wrong, and it cannot be ruled out by pre-election or parallel testing. Instead, BMD security relies on voters themselves detecting such an attack.”
