The most brazen, disruptive and manipulative attack on the American electoral system since Watergate — a vast cyberattack by Russia, aimed squarely at Democrats in 2016 — hinged on a series of human errors and institutional misjudgments. We talk with Eric Lipton and David Sanger, Times journalists who co-wrote a stunning story about out how the hack unfolded, moment by moment. We also talk to a victim of the attack.