A sophisticated attack on Microsoft Corp.’s widely used business email software is morphing into a global cybersecurity crisis, as hackers race to infect as many victims as possible before companies can secure their computer systems.The attack, which Microsoft has said started with a Chinese government-backed hacking group, has so far claimed at least 60,000 known victims globally, according to a former senior U.S. official with knowledge of the investigation. Many of them appear to be small or