A pair of Iranian hackers ran a sophisticated online campaign aimed at interfering with last year’s presidential election by threatening and influencing American voters, federal officials said Thursday. As part of their campaign, the conspirators got confidential U.S. voter information from at least one state election website and sent threatening email messages to intimidate people before they cast their ballots, prosecutors said. The disinformation duo also created a video that detailed false voting vulnerabilities, and even gained unauthorized access to a U.S. media company’s computer network — but were stopped before they could do any further damage to it, authorities...