How To know When your Facebook Account is been Hacked and the next step to take

For the second time this year, hackers have attacked millions of Facebook accounts. The social network announced last week that about 50 million users were recently hacked.
The hacking occurred because of a flaw in Facebook’s “View As” feature, which allows you to see your profile as others do. Users can type in a person’s name to get an understanding of what can be seen when a particular person is viewing their page.
This feature has been susceptible to attack since an update that occurred in July 2017.

Affected access tokens, which are like digital keys that allow a person to access their account without having to log in each time, were reset, forcing 50 million users plus an additional 40 million users to manually log back into their accounts. So if you were automatically logged out on all of your devices on the morning of Friday, Sept. 28, then there’s reason to believe your account was susceptible to the vulnerability.
Facebook said it did this as a precautionary step, logging out anyone who used the “View As” feature whether their account was actually affected or not. Users who were logged out do not need to change their password to be protected. The rightful owners of affected accounts will be able to log in with their current username and password.
Currently, the “View As” feature is not available while Facebook works to rectify the problem, those who try to use this feature should see an error message.
When Facebook announced the attack on its blog last Friday, it said affected users would receive a notification at the top of their News Feed when logging back into their account explaining what happened and what steps to take moving forward.
If you received this notification, you can select “Learn More” to get an understanding of how this breach will affect you. If you did not receive a notification at the top of your News Feed, your account was probably not affected by this security issue.
If you want to be extra safe, go to Settings– Security and Login– Where You’re Logged In to see if there are any unfamiliar devices attached to your account.
Facebook co-founder and CEO Mark Zuckerberg said the company isn’t sure about the source of the attack; nor is it clear if this breach led to users’ information being stolen or misused. The investigation is ongoing and those affected will be updated accordingly as the tech company learns more about the hack and the motives behind it.
The full extent of the breach is not known, but the company has alerted law enforcement and is working with the FBI to get to the bottom of the issue