TOKYO — Sony sat on info about a massive hack attack in April, according to a Ministry of Economy, Trade and Industry document obtained by the Kyodo news service.Reporting to the Ministry on May 6 about breaches that exposed the personal details of nearly 100 million subscribers to Sony game and music sites, Sony gave a chronology of events that indicated it knew about the incursion’s seriousness by April 24, though in a press release the next day it said only that it “could not rule out the possibility” of a hack. At that time Sony did not know the details of the data leak, including the type of user info compromised. Also, Sony veep Kazuo Hirai told reporters at a May 1 presser that Sony had first heard about the hacker invasion on April 25, in contradiction to its statement to METI. Sony later said in a statement that it sat on the news of the hack to avoid causing confusion to subs. The April hack was followed by others at Sony sites around the globe. Sony has since fully restored the services in the U.S., Europe and everywhere in Asia but Japan. Sony has estimated that the attacks will cost it $171 million in the current fiscal year.