Facebook is notifying users whose passwords it stored in plain text, which made them accessible for Facebook employees to view. Plain text means that the stored passwords are unencrypted, meaning they can be easily accessed and read by people who had access to Facebook s internal data storage systems. Between 200 and 600 million passwords were stored as early as 2012, KrebsOnSecurity reported. Facebook VP Pedro Canahuati said that the passwords were never visible to anyone outside of Facebook and that Facebook has found no evidence to date that anyone internally abused or accessed them.
Source: https://threatpost.com/facebook-stored-passwords-in-plain-text-for-years/143032/