Re: Must we authenticate login forms (using SSL?)?

[Antoine Martin <antoine () nagafix co uk>]

On Fri, 2005-09-30 at 15:15 +0000, Eoin Keary wrote:
> Hi is this over SSL, if not are you not subject to replay attacks?
Not necessarily over ssl, but if you are going down that route you could
re-use the same code over ssl too (a bit unnecessary but why not).
It should not be subject to replay attacks as long as you add a
per-session salt.

Antoine

> On 30/09/05, Antoine Martin <antoine () nagafix co uk> wrote:
> > > e.g. My bank logon script performs an MD5 hash of the username and
> > > password before sending it to the bank. The MITM tricks me to visiting
> > > their own site, and just "proxies" the comms to the real site. However,
> > > they strip out the MD5 hashing script,and replace it with an "identity"
> > > function (i.e. the output is the same as the input). When the MITM
> > > receives the form submission, it is trivial for them to extract the
> > > username and password from the form, replace it with the MD5 hash
> > > expected, and pass it on to the real bank.
> > Absolutely, that's why in my post I had said:
> > "The session can still be hijacked but at least the original
> > password is safer (as stealing it requires more work than
> > just listening in)."
> >
> > There is still some value in the approach suggested above, in the
> > context where the attacker can listen on the line but not proxy the real
> > server (and therefore not modify the page - not easily anyway).
> >
> > Regards
> > Antoine