Facebook detects if you are logged in Gmail

http://webapps.stackexchange.com/q/20018/40

by phwd • 15 years ago

268 85 15 years ago

webapps.stackexchange.com

irrumator2• 15 years ago

That's pretty neat, I wish they'd publish on how they did this so others could use it. Sounds like another great way to remove friction for the user, always a great thing.

dylangs10303• 15 years ago

Well...except people generally only appreciate these features when they're allowed explicitly. It's kind of unsettling having a website spontaneously know your activity elsewhere on the browser. Even well-intended, it can come off as tracking data.

irrumator2• 15 years ago

It is explicit, apparently FB is using OpenID which is information supplied by you linking the two accounts, completely opt-in. Besides, it's hardly tracking you with this feature, a boolean: is user logged in to Gmail? Yes|No

If yes, user can be verified quickly and reset their password in an easier fashion for them. Facebook is trying to make things smoother and not making you jump into your email to click a link or copy some token id or something. This is good UX.

nchuhoai3• 15 years ago

I think they should have used that information differently. Given they know that you are already logged into your gmail, any visitor to your machine will therefore know how to reset the password to his advantage.

Instead, they should have make a block, so that you are forced to logout of your gmail and login to your gmail to enhance security.

joshmlewis• 15 years ago

if they did this you might as well just go to your email and click on the link

nchuhoai3• 15 years ago

What i am saying is that you are forced to re-login to prevent someone stealing your facebook account when he has access to your computer. given that most people stay logged into their gmail, i think this would actually be helpful

antimatter154• 15 years ago

When I tried the same thing, it popped up a OpenID dialog the first time, and I confirmed it by seeing facebook.com on https://accounts.google.com/b/0/IssuedAuthSubTokens Revoking the facebook token causes Facebook to prompt again.

Subsequent attempts make the auth dialog flash briefly without displaying any content and still present the "You can change your password immediately because you are logged into your email account on this browser" message.

the_mitsuhiko4• 15 years ago

It's not very hard to do. The trick is to know a resource that only the user can access and then trigger an HTTP request to it.

For instance if you have website a and say the user profile "mitsuhiko" can only be edited when you are logged in as "mitsuhiko" on http://a.example.com/profile/edit/mitsuhiko you could use this code to see if the logged in user is "mitsuhiko":

    <script type="text/javascript" src="http://a.example.com/profile/edit/mitsuhiko"
      onload="user_is_logged_in()" onerror="user_is_logged_out()" async="async"></script>

Why does this work? Because onload is fired if the resource answers with 200 OK, not if it's a valid script. onerror is called for any other error code.

So if you know what you are probing for: easy.

// Edit: Yes, this is most likely not what Facebook is doing if that's their only method of security. However see my reply to the first comment here about the security aspect for a possible way to solve this problem.

antimatter154• 15 years ago

Except something like this would be easily spoofable, ie. you could set your hosts file to make all a.example.com links return HTTP 200's, or open firebug to call user_is_logged_in() and you could reset passwords without any email.

Also, for something like that you should use <img> instead so it's less of an XSS risk.

the_mitsuhiko4• 15 years ago

> Except something like this would be easily spoofable, ie. you could set your hosts file to make all a.example.com links return HTTP 200's, or open firebug to call user_is_logged_in() and you could reset passwords without any email.

Yes. But depending on how gmail works it could me made reliable and secure. For instance if you can share images with gmail users you could generate a unique image for that user, do the same thing with an <img> tag, access the image data with JavaScript, send it back to the server and compare if the contents are the one you shared.

I do not have a gmail account so I don't know if this is possible, it it seems like it would be possible for Google+ from briefly looking at it.

aiham• 15 years ago

You should post that as an answer to the question.

ks3• 15 years ago

I doubt FB uses that method. As explained in other threads it is too insecure.

ks3• 15 years ago

That's not a secure method. Because it's browser based it can be faked with a proxy or simply modifying the local hostname file and map the domain to a server you control.

patrickaljord• 15 years ago

This could guess that you are connected to your gmail but not to what gmail account, so this method would be pretty random.

mike-cardwell• 15 years ago

I wrote quite a popular blog post on how to check if a user to your site is logged in to GMail, Facebook, Twitter and Digg:

https://grepular.com/Abusing_HTTP_Status_Codes_to_Expose_Pri...

GMail doesn't seem to be working any more though. But the concept is still useful to learn.

raganwald3• 15 years ago

Not sure how they are doing this, but I have gotten tired of having to play “whack-a-mole” with FB scraping private information from my browser in other ways, so what I have done is sandboxed it: I have a separate “Facebook” account on OS X, and I assume that anything I do on that account is shared with Facebook.

I don’t log into Facebook for any reason on my normal user account, and I don’t log into anything else on my Facebook account. They can still sniff certain things using browser fingerprinting and so on, but this seems like the best I can do for the moment on my desktop.

xtacy• 15 years ago

With the "Like" button littered all over the web, Facebook can still connect you to all the websites that have the Like button installed! That's why I prefer AdBlock/Privacy Filters/even blocking Facebook domains by adding entries to /etc/hosts file to prevent even even a connection to their (known) IPs.

raganwald3• 15 years ago

I use lots of FB blocking in my regular account for that reason!

mlok• 15 years ago

I use ghostery to protect myself from this kind of tracking : http://www.ghostery.com/

brudgers• 15 years ago

I have a Ubuntu virtual machine(VMware Player) for Facebook only. I don't see any sufficient reason to link all my online activity to my account.

rapind2• 15 years ago

That's a pretty solid way to handle security. I wonder if there's a way to make sure you're always booting from the same starting point so that nothing is persisted to the image between vm sessions.

mekoka• 15 years ago

There's a comprehensive choice of browsers (http://en.wikipedia.org/wiki/List_of_web_browsers). I picked one that I knew I wouldn't need and dedicated it to my facebook usage.

pagekalisedown• 15 years ago

That's a great idea. I think I'll do the same for my online banking.

piggity• 15 years ago

Google Chrome's "users" should let you segment all your cookies and browsing neatly.

I use it to separate my various different Google identities and logins (so I can stay logged in with distinct accounts).

(Google's multiple sign-in is rarely effective or convenient)

zalew2• 15 years ago

being so afraid, what's the point of using it?

nitrogen• 15 years ago

I can't speak for raganwald, but in my case there are people who refuse to communicate using anything else.

ceol2• 15 years ago

>Not sure how they are doing this

Did you happen to read the answers? Two specifically mention that Facebook requests authentication access (OpenID, I believe) the first time. It appears this user authorized Facebook at some point in the past and forgot about it.

When I look at this page: https://accounts.google.com/b/0/IssuedAuthSubTokens I can see that at some point in the past, I allowed Facebook access to my Google Contacts (probably their "find friends" feature). Facebook could use that to check if you're logged in.

kamkha• 15 years ago

Did you happen to read the comments on the answers?

> Nope it's not that unfortunately. I tried it myself removing all linked accounts. The event above still happens.

code_duck• 15 years ago

I was browsing Facebook in Chromium in Mac OS when all of sudden, something started requesting Key Chain access for just just about every web site login I have stored. Coincidence? I have no idea what was going on, never happened before or since.

falling2• 15 years ago

Do you (and anyone else on this thread isolating Facebook to prevent tracking) do the same for Google?

raganwald3• 15 years ago

I use DuckDuckGo: http://donttrack.us/

haakon2• 15 years ago

Kind of – I have one separate browser for Facebook and Google (as in all Google products where I'm logged in). All my other browsing is done in my main browser through Tor, including my searches for which I use Scroogle.

Hitchhiker• 15 years ago

In Criminal Minds, they talk about a perp devolving .. as business pressures increment[1] .. these incidents will only increase in occurrence and decrease in terms of surprise for users.

[1] http://www.foxbusiness.com/technology/2011/11/04/investors-u...

andresmh• 15 years ago

I do this with Mozilla Prism http://prism.mozillalabs.com/

jeromeflipo• 15 years ago

Chrome supports multiple profiles now, see http://chrome.blogspot.com/2011/11/take-your-chrome-stuff-wi.... I can't believe so few HN readers know this, since it's the best way to use seperately Google Apps and Gmail accounts. It works for Facebook too, obviously.

You can sync all Chrome browsers, on all your devices, with both your Google Apps account for work and your personal Gmail account. It means that each profile have their own bookmarks, history & most visited pages, extensions, saved passwords (...) synced in real-time (you can even sync open tabs!). It's very powerful to improve your focus, because you only use 1 browser (no need to switch your habits) and you're never get distracted by notifications, mails, docs, rss when you're in your work/perso "station".

Fortunately, you can keep your Gmail/Google apps chat accounts of each profiles open in the background with the official Google Talk extension https://chrome.google.com/webstore/detail/nckgahadagoaajjgaf... (works on Mac, Windows, Linux & ChromeOS).

dextorious2• 15 years ago

How about not logging to Facebook at all?

You don't seem like the kind of user FB targets anyway...

k-mcgrady2• 15 years ago

Facebook doesn't really have a targeted audience anymore. It's pretty much everybody. At this point its like deciding not to use the telephone because the line could be tapped. Facebook is becoming an essential communications platform for a lot of people. Particularly people under 20.

guygurari• 15 years ago

> I have done is sandboxed it: I have a separate “Facebook” account on OS X

At what point will you decide to ban Facebook? Will you stop using their services if they find a way to spy on your cross-browser behavior? Or will you just sandbox them further into a VM, or even another physical machine? What if other sites you use regularly also start tracking you so aggressively?

I deleted my FB account when I learned that more of my profile info was being made public over time. This was before Like buttons.

I was not a heavy user, but this decision had its price; there are people I no longer communicate with because of it. Still, I'm happy I took a stand, all the more so because things have deteriorated much further since then in terms of privacy.

naner• 15 years ago

It probably would be simpler to just use porn browsing mode to access FB.

charlieok• 15 years ago

I have been spending a lot of time looking into how to best solve the web's current facebook problem. I'm especially interested in approaches to distributed social networking (think what the Diaspora guys are aiming at).

With that preface, it's my impression right now that https://singly.com deserves a serious look from communities such as hacker news. So, I'm mentioning it here.

A little about them: they're led by the guy who created XMPP (aka Jabber). He's written a new distributed protocol based on JSON instead of XML ( http://www.telehash.org/ ). They've been joined by the guy who lead Canonical (publishers of Ubuntu). Like Wordpress, they are part free software project and part optional hosting company.

No, I am not affiliated with them. But I am really thinking that I would like to be...

jvandenbroeck• 15 years ago

So Facebook uses oauth to login with google, I don't get why this is worth 114 points..

eddieplan9• 15 years ago

IMHO, this does not seem to be related to OAuth. OAuth is three-leg authentication, and the service provider - Google in this case - will prompt the user to allow the consumer - facebook in this case - to allow an authentication attempt. Except of course the user has done the authentication in a previous attempt and facebook cached the token, but based on facebook's wording, because you are logged into your email account on this browser, does not seem to support this.

jarin• 15 years ago

I ran into that the other day, and was pleasantly surprised. This is how interconnectivity is supposed to work.

fauldsh• 15 years ago

Exactly my thought as well, it's a pretty cool feature.

res0nat0r• 15 years ago

Another day, another post up in arms about Facebook privacy. This is getting old.

MartinMond3• 15 years ago

I bought http://fluidapp.com/ just for Facebook.

Now I have a nice separate window for browsing Facebook and nothing but Facebook.

Separate cookie store is awesome.

gibybo• 15 years ago

I like the idea, but I'm not sure if I can trust this level of sand-boxing. Does it also use a separate cache (web history, etags, image cache, web cache, etc)? a separate Flash storage? Silverlight storage? HTML5 storage? If any of them are shared, something along the lines of Evercookie would have no problem maintaining cookies across the apps.

MartinMond3• 15 years ago

Cache is completely separate, Flash and Silverlight (and plugins in general) aren't sandboxed, which is why I deactivated them for my Facebook Browser. (no more embedded youtube videos, but they open in my main browser, works just as well)

nikcub3• 15 years ago

Doesn't fluid share the same default cookie store as Safari?

It definitely does on my version, which is 6 months old, but it caused me to not use it.

MartinMond3• 15 years ago

Not any more. He rewrote it and made separate cookie store a paid feature.

albertzeyer• 15 years ago

Reminds me of my own (open source) project which does the same based on Chrome: https://github.com/albertz/ChromeWebApps

It uses (by purpose) the same session though as the main Chrome instance.

But it should be possible to implement an option to use a separate session. This might even be much simpler than my current approach (which not only shares the session, it also uses the same Chrome process).

dylangs10303• 15 years ago

Question...has anyone noticed if this relationship is reciprocal? I keep an eye on my Gmail ads to see how far along they track my activity while I am logged in and browsing, but has anyone noticed Gmail ads showing content that wouldn't be there without placement or data from Facebook? Obviously this doesn't apply if you sandbox Facebook as some commenters have, but if you use both in one browser I mean. I may use Firebug and see if the two communicate while I'm logged in...

nikcub3• 15 years ago

It must be using oAuth. I think it was a mistake in the oAuth protocol to not build in a default, short, expiration for secret keys. Now users (most of them non-tech savvy) have to rely on visiting the apps page and manually removing authorizations.

Edit: I just profiled the process, and it is using OpenID. It pops open a new window that will check your OpenID login and call back with a success and will close the window if it is. I had to slow down my connection to actually see it.

Canada• 15 years ago

This is why facebook never gets on my noscript whitelist, why I only use it in a private browsing session and why I hardly ever login.

zecg• 15 years ago

This is really handy: http://disconnect.me/

zerostar07• 15 years ago

I ve seen this screen, but it only comes up after you give facebook Oauth access to your Gmail.

whackberry• 15 years ago

Facebook is amateur when compared to Google

Facebook detects if you are logged in Gmail

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