Facebook says it has analyzed the data surrounding last week's attack and found no evidence to suggest the hackers used the login tokens to access apps using Facebook login. About 50 million users' accounts were left vulnerable due to a bug in the "view as" tool. Facebook reset the tokens of those 50 million, plus another 40 million users whose profiles had been used in a "view as" search. Facebook says resetting the tokens, which forced app logouts, protected customers. Moving foreword, the company is building a tool to let developers manually identify their own users so they may see who was impacted by this and other hacks. Facebook implores developers to use the official Facebook SDKs for Android, iOS, and JavaScript, which will automatically ascertain the validity of access tokens on a daily basis. It also suggests that developers log users out when they discover error codes showing invalid Facebook sessions. Facebook once again apologized for the hack and said its investigation is on-going.