Re: Plaintext passwords

On Fri, Oct 10, 2008 at 2:09 PM, Simon Friedberger
<[email protected]> wrote:
>
> Phew.
> I just read through the original "[jadmin] jabberd14 'crypt' password
> storage in postgressql" thread.
>
> Very interesting indeed.
> The main point seems to be:
> We cannot protect users from mitm when storing the password as a hash
> only.
>
> Let me try to write a summary:
>
> a) The passwd approach:
>        Pro: The server does not store the passwords.
>        Con: The password has to be sent over the wire.
> b) The CRAM-MD5 approach:
>        Pro: The password is not sent over the wire.
>        Con: The server has to store the password.

I'm not convinced these are the only two options. There are certainly
authorization protocols in which the password only exists to create a
hash, and neither side has the unencryted password stored.

~ Anders

>
> Simple, isn't it? :)
>
> Now let's look at what might happen:
>
> I. The jabber server is compromised:
>        Either way the attacker gets everything.
>        The not-so-subtle difference is:
>        Using case b) The attacker immediately has access to the users password.
>        He may use the password to access other services where the user chose the same password.
>        While in case a) the attacker still has to:
>                1. successfully mount an offline attack on the hash.
>                2. impersonate the server to get the password when the
>                user logs on.
>
> II. MITM:
>        Assuming a secured line the attacker has to impersonate the
>        server without knowing the appropriate private key and the user
>        is prompted with a false certificate.
>        The user accepts that certificate.
>        In case a) the attacker immediately has access to the users
>        password. In case b) the attacker can only listen in on and
>        alter the users chatdata.
>
> Still pretty simple but which choice is to prefer?
>
> In both situations the users jabber account is compromised and it seems
> reasonable to examine _further_ damage. Consider the security unaware
> user who made the mistake of using the same password for multiple
> services.
>
> I then advocate a) is the better choice because:
>
> Case II. is imho difficult for the attacker because
> it
> - requires the attacker to be able intercept and alter the users traffic
> - requires the user to accept a false certificate
> while Case I. can occur if simply
> - an admin account is compromised
> - a local user escalates his privileges
> but _also_ if only the password database is compromised.
>
> Now maybe somebody would like to add something, change something. Feel
> free!
>
> At least I think that it should be obvious that this is a design choice
> depending on the setup and it should be configurable. The recurring and
> extensive discussion seems to prove that point.
>
> Ciao
>        Simon
> _______________________________________________
> JAdmin mailing list
> FAQ: http://www.jabber.org/discussion-lists/jadmin-faq
> Forum: http://www.jabberforum.org/forumdisplay.php?f=19
> Info: http://mail.jabber.org/mailman/listinfo/jadmin
> Unsubscribe: [email protected]
> _______________________________________________
>
_______________________________________________
JAdmin mailing list
FAQ: http://www.jabber.org/discussion-lists/jadmin-faq
Forum: http://www.jabberforum.org/forumdisplay.php?f=19
Info: http://mail.jabber.org/mailman/listinfo/jadmin
Unsubscribe: [email protected]
_______________________________________________