Re: Session security with cookies

["Scott C. Sanchez" <scottsanchez () gmail com>]

Encrypting or signing the data in the cookies is better than not doing
it.  My suggestion instead would be to use a hash of something unique
in the cookie (by itself) that maps back to a server-side table
linking the valid hashes to the data you are trying to keep track of.
The only gotcha here is to not use something predictable as the hash (
e.g. the users email address), because then someone can brute force
their way into figuring out your hash.  Random is your friend!

That way there is no data in the cookie to get tampered with (or
stolen), and if you get paranoid and use something robust like sha512
for the hash you store in the cookie, there is little chance anyone
will be able to spoof another user by 'guessing' the hash in their
cookie.

-Scott

> On Dec 4, 2007 1:47 PM, Ron <ronlists () skullsecurity com> wrote:
>
> > Something I've recently been toying with is the idea of
> > encrypting/signing cookies with a private key on the server. The the
> > cookies can't be read or tampered with by the user, nor can they be
> > stolen by cross-site attacks and the like.
> >
> > This isn't something I've done a lot of work with, however, so I may be
> > missing something obvious, and am open to comments on the idea.
> >
> > Ron
> >
> >
> > Till Elsner wrote:
> > > Hi, i'm investigating in web application security this time and i'm
> > > trying to find some information about session management with cookies
> > > and related security issues. Can anyone point me to tips on how to make
> > > cookie based sessions more secure and how to prevent session hijacking?
> > > How secure is session handling using cookies and what are the main
> > > risks? Is anyone aware of good literature on that topic?
> > > Thanks and have a nice day
> > > Till
> > >
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>
> --




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