The "Facebook Warning 18+ Adults Only" Phishing Scam
The link in the message or comment goes to the following phishing or fake Facebook website:
On the phishing website, visitors will be asked to sign-in with their Facebook accounts. If they attempt to sign-in, their Facebook usernames and passwords will be sent to the cybercriminals behind the scam.
Once the cybercriminals receive the stolen usernames and passwords, they will use it to gain access to the Facebook accounts of their potential victims and use their accounts to send spam, malicious messages, post phishing comments, and use the accounts for other fraudulent activities.
Facebook users who have already been tricked by the scam are asked to change their password immediately before their accounts are hijacked and used maliciously. Click here for instructions. And, for Facebook users whose accounts have already been hijacked, should click here for help recovering them.