If stockholders of Equifax Inc (NYSE:EFX) were smarting after the credit referencing group on Tuesday told the market that it had underestimated its data breach by some 2.5mln accounts, they may spare a thought for Verizon executives as Yahoo has revised its assessment of a 2013 hack.
The full extent of the data breach at Yahoo! has now emerged, with the internet business admitting that its entire user base of 3bn accounts was breached.
That’s three times more users than Yahoo’s prior estimate that 1bn accounts had been compromised. The company said that the new estimate was informed by additional analysis helped by third parties including computer forensics.
Yahoo disclosed information about the 2013 breach back in December 2016, before the company’s internet businesses were acquired by Verizon in June.