Russia's military intelligence unit known as Sandworm has, for the past decade, served as the Kremlin’s most aggressive cyberattack force, triggering blackouts in Ukraine and releasing self-spreading, destructive code in incidents that remain some of the most disruptive hacking events in history. In recent months, however, one group of hackers linked to Sandworm has attempted a kind of digital mayhem that, in some respects, goes beyond even its predecessor: They've claimed responsibility for dir...