Penetration Testing mailing list archives

Re: IIS 5 cookie encryption password


From: "Serguey Forcade" <sergueyf () gmail com>
Date: Tue, 3 Apr 2007 12:32:58 -0400

Thanks, but I based my assumptions on an article from Microsoft
(http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/iisbook/c06_asp_session_id_and_session_security.mspx?mfr=true)

Even tho your statement makes sense. It's just that I haven't been
able to find more info about the relationship between the session ID
and the cookie.

On 4/3/07, Rogan Dawes <discard () dawes za net> wrote:
Serguey Forcade wrote:
> Hi, I'd like to know if anyone knows of a paper that explains how to
> extract the encryption password IIS creates when it starts up, and
> uses to encrypt the session ID + random data in order to generate the
> cookie value the users receives.
>
> I'm interested in IIS 5.0.
>
> Thanks.
>

Take this with a pinch of salt, but I don't think that the session
identifier and the cookie value are directly related.

One reason for this statement is that if you abandon the session (using
ASP), and create a new one, the cookie value does not change. However,
the result of "Session.SessionID" DOES change.

I suspect that the cookie value is generated using a combination of some
static/sequential info, and some random data, and then associated with
the next available (i.e sequential integer) SessionID. When the session
is abandoned, the session object associated with that integer SessionID
is discarded. A subsequent request from the client containing the old
Session Cookie value will then automatically be associated with the next
available sequential integer SessionID.

Hope this helps.

Rogan

P.S. One consequence of this inability to change the cookie value
through abandoning the session is that ASP apps are AUTOMATICALLY
vulnerable to Session Fixation
<http://www.owasp.org/index.php/Session_Fixation>. An approach to
protecting ASP apps against session fixation is shown here
<http://www.owasp.org/index.php/Session_Fixation_Protection>


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