full-disclosure - Re: [FD] Session Hijack Vulnerabilty on ebays german want ad?

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Message-ID: <2C6C53084E402141A75D7D5589DD46E5015593B3@mscas.materna.com>
Date: Tue, 24 Jun 2014 06:55:55 +0000
From: <Cengizhan.Yuecel@...erna.de>
To: <waffenklang@...glemail.com>, <fulldisclosure@...lists.org>
Subject: Re: [FD] Session Hijack Vulnerabilty on ebays german want ad?

Hi Christian,

as you first logged in on Computer A, you authenticated yourself by showing possession of the current password. Afterwards the application created a session for you with a unique Session-ID and maybe some more session data. From that point on your browser gets access to the application by simply showing knowledge of that session data, not the password anymore. For that purpose the session data is usually stored in a cookie by your browser and the application. If you additionally chose to stay logged in at the time of your login by password, depending on the application the session may also survive restarts of the browser, e.g., even if there are passing days between the stop and the start of it.

Changing the password and logging in from another computer (B) does not necessarily have to affect the first session. This again depends on the application. There are applications that do not allow for more than one session. In that case, creating a new session automatically terminates the old session, no matter if there happened a change of the password in between. Eventually it's a matter of session management design.

Summing this up: It does not necessarily has to be a security flaw / attack vector. It depends on the intention of the application designers, especially if this is a wanted behavior regarding their session management.

Kind regards
Cengizhan

-----Ursprüngliche Nachricht-----
Von: Fulldisclosure [mailto:fulldisclosure-bounces@...lists.org] Im Auftrag von Christian K.
Gesendet: Montag, 23. Juni 2014 20:22
An: fulldisclosure@...lists.org
Betreff: [FD] Session Hijack Vulnerabilty on ebays german want ad?

Hi,

i have a question if this is an attack vector (website is german want ad
branch from ebay kleinanzeigen.ebay.de prob. english site affected too):

On Computer A the browser (FF) has an open tab with the site where, when
visited, user A is always signed on (because the specific site is the user
panel).

On Computer B user A wants to log into his account, but forgot his
password. He successfully changed his password using the "forgot password"
button and was able to log in.

Then user A moves from Computer B to Computer A (which was off at the time
user A was at Computer B) and starts its browser where he realizes that he
is still logged into his account on the site without any password
confirmation.

As this happend to me, the question is: is this an attack vector (I assume
it is) and how can I as a user protect myself? Am not really into security
engineering (just non-sec-related software engineering...), so forgive my
dumbness!

Thanks.

C.

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