full-disclosure - Re: [FD] Access anyone's Facebook "profile picture" in full resolution regardless of the ACL restriction

Open Source and information security mailing list archives

Date: Thu, 03 Apr 2014 12:07:29 -0400
From: illwill <illwill@...mob.org>
To: fulldisclosure@...lists.org
Subject: Re: [FD] Access anyone's Facebook "profile picture" in full
 resolution regardless of the ACL restriction

did you know the second section of the filename is the users actual
facebook user id?
6549_*16544614736*_444444875_n.jpg
https://www.facebook.com/profile.php?id=*16544614736

*
        -illwill
illwill@...mob.org
http://illmob.org

On 4/1/2014 5:59 AM, Bipin Gautam wrote:
> Hi List,
>
> I felt like writing / pointing this minor issue, as it as its "Facebook" ...
>
> This issue is due to the way facebook pictures are stored in CDN
> without authentication mechanism, during accessing it. (which would be
> way technically complicated to implement it)
>
> Also, it is a Facebook feature that... if you have full path of an
> image, you can pass it to anyone over the internet which they can
> access it directly (and the facebook user should not have unrealistic
> expectation to privacy. Hence, if someone can access an image they can
> save/email it to others, anyway.)
>
>
> POC:
>
> ( Please TEST it in a real profile, real world example and it should
> work. I obviously changed the URL, POC below, to gibberish
> "6549_16544614736_444444875_n.jpg" )
>
> STEPS:
>
> You could try this by :
>
> - changing your own facebook profile picture viewable to "only me",
> then bookmark your own Facebook profile and logout and clear cache.
>
> - or then try different browser with your own profile from bookmark,
> without logging in to facebook!
>
> - or pass your FB profile to a friend, with the following instruction.
>
> ___
>
> - then, in your browser, "Right click the Facebook profile image" that
> you want to access in full resolution (that have ACL as access to
> "only me" or "friends" ) > click "Copy image location" > paste it in
> notepad
>
> sample url you will get (this link below is broken)
>
> :[1] https://fbcdn-profile-a.akamaihd.net/hprofile-ak-frc3/t1.0-1/c0.18.160.160/p160x160/6549_16544614736_444444875_n.jpg
>
>
> to remove from [1]: "/c0.18.160.160/p160x160"   (part; in other cases,
> the url structure may be different, you just have to find and remove
> this middle part...)
>
> final modified url from above, which you can access the profile
> picture in full resolution via your browser :
>
> https://fbcdn-profile-a.akamaihd.net/hprofile-ak-frc3/t1.0-1/6549_16544614736_444444875_n.jpg
>
>
> Respectfully,
> -bipin
>
>
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