An attacker with physical access to a voting machine can install fraudulent vote-miscounting software. Older machines (Shouptronic, AVC Advantage, AccuVote OS, Optech-III Eagle) can be hacked by anyone with. physical access. newer machines (almost anything else in use today) are vulnerable to attacks from the Internet. Optical scan machines, even though they can be. hacked, allow audits and recounts of the paper ballots marked by voters. This is a very important safeguard. Paperless touchscreen machines have no such protection.”]
Source: https://freedom-to-tinker.com/2016/09/20/which-voting-machines-can-be-hacked-through-the-internet/