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Date: Fri, 04 Oct 2013 00:07:02 -0600
From: Kurt Seifried <kseifried@...hat.com>
To: Donald Stufft <donald@...fft.io>
CC: oss-security@...ts.openwall.com
Subject: Re: A note on cookie based sessions

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On 10/03/2013 11:26 PM, Donald Stufft wrote:
> I don't think this really is a vulnerability is it? I mean it's
> basically how the internet works. The only difference between a
> cooke backed session and a regular session is that there's no
> server side session to destroy. At least in Django's case, It's not
> a permanent session though, they are only good for a limited amount
> of time before the signature on the cookie expires.
> 
> If you have access to the session cookie you've already won the
> game, you've gotten an XSS or MITM and can do much worse then a
> session cookie.
> 

Apologies I should have been more explicit. The difference is that
with a stateful backend when the user  hits log out they are logged
out in the back end, so the cookie can't be used any more. With these
stateless solutions there is no way to prevent cookie reply other than
encoding a time out in the cookie (so I guess you could encode like a
short time out and keep rotating the cookie to close the window of
opportunity).

The concern is people using public terminals, cookie stealing attacks,
XSS in the website you're using, etc allowing an attacker to snag your
cookie and use it post "log out".


- -- 
Kurt Seifried Red Hat Security Response Team (SRT)
PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993
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