Passwords For Your Facebook Account

http://www.labnol.org/internet/facebook-account-passwords/21241/

by heroic • 14 years ago

155 59 14 years ago

This raises several questions:

Have they always done this, or is this new?

For those of us who haven't changed our Facebook password in years, does this mean that we don't get this option, or do we? And if we do, is Facebook storing our passwords in plaintext?

heroic2• 14 years ago

They dont need to store your pasword in plaintext for this, but it does raise a security concern. 3 times the chances to have your password guessed by brute force!

masterzora2• 14 years ago

Given a reasonably sized keyspace (which FB does have) a factor of three should not be a big deal.

FaceKicker3• 14 years ago

It's actually much more than 3 times the chance; this rule allows you to restrict your brute force search to only check passwords with no uppercase characters (or no lowercase characters) which reduces the key space for a given maximum password length quite a bit. (e.g., if there were normally 100 characters allowed and n is the max length, taking out 26 characters reduces the search space from 100^n to 74^n - not that an intelligent password cracker would ever try to iterate straight through the actual space of all allowable passwords)

Im_Mr_Manager• 14 years ago

I think we can be pretty certain Facebook already has robust login attempt throttling systems in place.

mille562• 14 years ago

They are probably still storing hashed passwords. It would require hashing your login attempt 3 times: 1) exactly you typed it 2) forcing first character to be lower case 3) inverting the case of all letters.

raquo2• 14 years ago

You don't need to store the password in plaintext, you can just capture the password from a successful login attempt and generate new acceptable hashes from different variations of it. That way you'd gradually add this feature for most of the active accounts.

0x02• 14 years ago

You don't even need that. When you receive the password, you can compare the stored hash against:

  hash(password)
  hash(password-inverted)
  hash(password-first-upper-case)

This way it'll work with an inverted password even on the first attempt (after this feature was implemented)

Edit: Going by my gut feeling only, this feels slightly more secure too... If the hashed password database is ever leaked, it feels like it would be easier to crack a password given the three related hashes, compared to just the one.

wunderland• 14 years ago

I don't understand. So, you type in your password, and this input is sent (securely?) to their server, where it is hashed, and this hash is checked against their stored hash. But they can also "capture" this password prior to it being hashed? But then Facebook could do a few string manipulation operations, and then securely delete the un-hashed password from memory. Am I understanding this correctly?

msbarnett• 14 years ago

You don't need to have the user change their password to implement this kind of change -- you can generate and store the additional hashes after any successful login attempt.

masterzora2• 14 years ago

Rather than asking questions I tried some science. Last time I changed my FB password was roughly 6 months ago and I am only able to get the correct-case password to allow access. I'm not too inclined to spend much more time on this but surely someone who hasn't changed their password in a while can try it out. They can see if the alternate casings work, change their password and see if they work then, etc.

TamDenholm• 14 years ago

Ignoring the security implications for a moment, this is a very nice UX enhancement, I do imagine that it would eliminate the vast majority of the invalid password attempts thus making people's experience much better.

Now, the question is, just how much security are you losing by allowing this? Assuming the passwords are stored correctly my guess would be that passwords that are considered secure already would only be marginally less secure because of this, however non secure passwords (common ones) are a hell of a lot less secure but only in a relative context, they're still just as insecure as the original insecure password.

I'm not sure I articulated this properly so if I didn't let me know.

TazeTSchnitzel• 14 years ago

I'd say half the possible combinations are gone, minus one. I don't think that's too bad.

And I agree it's a great UX enhancement. I've been frustrated many times entering usernames and passwords with my phone defaulting to capitalising the first letter.

Now if only they'd strip # from the end of posts again (on UK keyboards at least it's right next to the return key, so many posts end up looking like this#

kijin2• 14 years ago

> half the possible combinations are gone, minus one

So, slightly more than one bit of entropy lost?

peeters• 14 years ago

Most insecure passwords don't use mixed case anyhow (dictionary lower-case words), so I fail to see how this is making them much less secure.

In fact in terms of relative impact, this has a much greater impact on "secure" passwords (in this case, I mean ones that are a random jumbled set of mixed case letters and numbers). That's only really because it significantly reduces the range of the first character.

mistercow• 14 years ago

I would also argue that the security implications of this are largely positive. It removes less than two bits of entropy even from a randomly generated password, but it means that users reset their passwords less often, and I would guess that when users reset a "forgotten" password, they usually choose something weaker (and thus more memorable).

27182818284• 14 years ago

Does Facebook ask to prove yourself with another form of auth if you're logging in from an unusual place? I want to say it does, but I can't recall for sure.

Anm• 14 years ago

I'd like to note, their assumptions on caps lock does not apply to Mac. If you hold shift while caps lock on a mac, it still gives uppercase.

Of course, if they implemented this, it would turn it into a case insensitive password with much bigger security implications. So, this isn't a criticism of their decision. Only an observation.

chengiz• 14 years ago

You can also login with your profile name, which I didnt know until very recently when I mistakenly dropped the @domain.com and was initially surprised to find it worked.

why-el• 14 years ago

That only works if you actually change your profile name to something meaningful like facebook.com/yourname. A lot of people don't do that (they have an autogenerated id) and in that case the email is mandatory. I should also note that you can only change your profile name, i.e. facebook.com/profilename, twice. That is, going from something like facebook.com/profile.php?id=34534643 to facebook.com/profileName1 to facebook.com/profilename2. After that Facebook won't allow you, for some reason.

kirarev• 14 years ago

Also, phone number works too if you have it listed (possibly cell-only).

hafabnew• 14 years ago

While obviously Facebook will be storing this as hash(normal), hash(upper(normal)), and hash(lower(normal)), there's an interesting security benefit to storing this in 3 columns, 'password1', 'password2' and 'password3'. The trick then is to randomise which hash gets stored in which column, i.e., password1 doesn't always correspond to hash(normal).

The slight benefit of this being that if your database is leaked, then the attacker won't have his/her brute forcing job made easier by knowing that the password3 hash only contains lowercase alphanumeric characters.

Edit: Apparently I suck at reading, it's not upper() and lower(). Woops :). Well, if any other sites do store upper() and lower() variations, I wonder if they use this idea?

losvedir• 14 years ago

It doesn't really provide much extra security. The factor of 3 slow-down it provides (having to check against three columns instead of one) is a small constant factor in the exponential task of brute-forcing.

rplnt2• 14 years ago

I don't think they store three hashes though. Just the original one and they check against that. Only if that fails they proceed to verify other variants. There are only two - first letter uppercase (presumably for stupid phones) and inverse password (for caps lock on PCs). Both of these variants are reversible (i.e. you can revert the change to get original the password).

aneth2• 14 years ago

One interesting observation from the comments:

On a Mac, shift with caps-lock on doesn't toggle to lower-case, so they would need to store a fourth version for this to work.

OPERATI@NGERONIMO

Overall it's a clever UX hack, though I worry they came to it by observing invalid password attempts which seems slightly outside of appropriate, although it doesn't particularly bother me in this case.

MartinCron2• 14 years ago

That would make all passwords essentially case-insensitive (all uppercase would work) and that would make it much easier to brute force than the inverted version.

aneth2• 14 years ago

True, and a good reason not to implement this solution.

dkersten• 14 years ago

My capslock key is backspace, so this feature is useless to me.

Dave_Rosenthal• 14 years ago

Also, I just noticed this evening that Facebook explicitly notifies you of incorrectly using your old password. Not sure how long far back they go to check.

pazimzadeh2• 14 years ago

The question is, what IS the value of the true password? How do you define "something and its inverse?"

rplnt2• 14 years ago

I don't think I follow. What is the question?

(To get inverse password you simply reverse the case on all letters.)

pazimzadeh2• 14 years ago

I mean that while facebook prompts you for a password in a single field, if you enter "passWORD" the true value of your password is both "passWORD" and "PASSword", but there's no way to express that idea in the english language. If someone asked you what your password was, what would you say if you wanted to be completely accurate?

It's just a dumb philosophical thought I had.

davweb• 14 years ago

There's a nice article about this on the AgileBits blog [1]. In summary they say it's a net gain for security because trying variations on a supplied password doesn't help an attack much and reducing the number of password resets is a positive from a security perspective.

[1] http://blog.agilebits.com/2011/09/13/facebook-and-caps-lock-...

Passwords For Your Facebook Account

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