It's 3 Billion! Yes, Every Single Yahoo Account Was Hacked In 2013 Data Breach
A little-known technique used by hackers which is not widely known by the general public. It’s easy to go and buy users information from breaches. Why is this useful you might ask? Because it is highly likely that having access to one or more password samples and a user's secret questions & answers can lead to gaining access to other accounts used by that user. Studies have shown that most users use a common password and secret question(s) across their private and corporate accounts. Further vendor identity and access management software normally compound the issue by not allowing users to choose different secret questions to that of other online services. This all puts your corporate accounts at risk. Try it and you will be surprised at what you will find.
Corporate Threat Intelligence/ Hunt teams should be analyzing breach data to see if any corporate personal have been breached on private accounts.