Federal authorities are offering a reward of up to $10 million for information on the whereabouts of a Russian national who they say is connected to a sprawling cybersecurity attack on Ukrainian government computer systems ahead of Russia’s invasion of the country.The planned attack, known as “WhisperGate,” also targeted one of Ukraine’s Central European ally nations and included attempted probes of U.S. government facilities in Maryland, according to an indictment unsealed Wednesday morning.A f...