Mark Zuckerberg swears he found out just two weeks ago that bad actors were harvesting users’ private info by the millions. But the company was alerted long, long before that. Facebook was warned five years ago that the “reverse-lookup” feature in its search engine could be used to harvest names, profiles, and phone numbers for virtually all its users. But the company ignored the red flags until last week, after it happened. In prepared testimony to Congress released Monday, Mark Zuckerberg acknowledged that malefactors had used the reverse-lookup “to link people’s public Facebook information to a phone number,” he wrote...