Facebook login page still leaks sensitive info
Security malpractice 101
Facebook's login system continues to spill information that can be helpful to phishers, social engineers and other miscreants attempting to scam the more than 500 million active users of the social networking site.
When a legitimate email address is entered along with an incorrect password, the authentication system returns an error that reads: “Please re-enter your password. The password you entered is incorrect. Please try again (make sure your caps lock is off).” When an email address that doesn't belong to a Facebook user is entered, the response is: “Incorrect Email. The email you entered does not belong to any account.”
The difference in the wording makes it possible for anyone to discern whether a given email address is registered on Facebook, even when the corresponding password is unknown. It was flagged to us by Reg reader Ben Prescott, a security analyst for EMC Corporation's Critical Incident Response Center, who calls it “one of the oldest security malpractices in the book.”
The configuration makes it possible to verify the validity of huge numbers of email addresses. It has been in place since last week, when Facebook developers fixed a much more serious bug that allowed attackers to match unknown email addresses with users' pictures and full names. It worked even for accounts that were configured to be private. It came to light after a researcher published a simple script that could quickly scrape large numbers of names and pictures that corresponded to email addresses.
While the new setup offers considerably less information, it could still be helpful for people trying to guess the email addresses of people in a given company or organization. And there's no reason this hack couldn't be automated, either.
It wouldn't be surprising if Facebook changed this setting soon. ®
If this is considered a security flaw....
then el reg is guilty of it to.
Go to http://account.theregister.co.uk/reminder/ and type in an email address. If its a valid, it will say a reminder has been sent. If its not valid it says:
"That address does not appear to be registered."
Good way to get a list of valid email addresses, then next step is to try and get passwords.
Just an example, facebook isn't the only one who does these type things.
On the plus side...
... it's enabled me to positively prove that I really did delete my account with them some months ago.
Most systems (e.g., ftp and ssh servers) stopped leaking data this way about twenty years ago. There is no excuse whatsoever for designing the login page this way.
That their 'fix' is to stop displaying names and pictures, rather than changing the underlying behavior, is yet another demonstration that they have no understanding of privacy or security.