Facebook is reportedly buying stolen passwords that hackers are selling on the underground black market in an effort to keep its users’ accounts safe. Over 1.3 Billion people use Facebook every day, and keeping them secure is building attack-proof software to keep out hackers, but keeping them safe is actually a huge task. Facebook CSOsaid that the biggest headache he deals with is caused by passwords users keep securing their accounts. The social network then alerts tens of millions of users that their passwords needed changing as they were not strong enough to protect their accounts.
Source: https://thehackernews.com/2016/11/facebook-acccount-password.html