Yahoo faces growing scrutiny over when it learned of data breach

By Dustin Volz WASHINGTON (Reuters) - Yahoo on Friday faced pointed questions about exactly when it knew about a cyber attack that exposed the email credentials of 500 million users, a critical issue for the company as it seeks to prevent the breach from affecting a pending takeover by Verizon Inc . The internet company has so far not provided a clear, detailed timeline about when it was made aware of the breach announced Thursday. Yahoo blamed the incident on a "state-sponsored actor" but has n