WASHINGTON—Sen. Claire McCaskill, a Missouri Democrat facing a tough re-election fight, said Thursday that hackers aiming to steal staffers’ passwords failed to infiltrate her Senate office computers, an attempted breach that echoed high-profile thefts during the 2016 presidential campaign.
Earlier Thursday, the Daily Beast website reported that hackers tied to Russia’s GRU intelligence service used a phishing technique to try to trick McCaskill staffers into clicking on malicious web links in order to steal their passwords,…