Re: On the topic of SSL and MD5 (was Re: [NSE])

[Brandon Enright <bmenrigh () ucsd edu>]

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On Mon, 12 Jan 2009 14:40:41 -0600
MadHat Unspecific <madhat () unspecific com> wrote:

> Brandon Enright wrote:
> > On Mon, 12 Jan 2009 10:46:39 -0800
> > bensonk () acm wwu edu wrote:
> >
> > ...snip...
> >
> > > There's also a link to another blog
> > > post which describes exactly how[4] MD5 sigs can be made safe.  
> <snip>
>
> > The best solution is to remove all CA certs that sign with MD5 from
> > your browser trust.  It is naive to think in a MitM scenario your
> > Nmap scanner is going to scan and detect a cert signed using MD5
> > *before* the attack starts.
>
> Not what anyone was thinking, as far as I know.  Once again, the idea
> of the scan to detect an MD5 signature was not to prevent anything
> bad from happening, but to manage expectation of management.  The
> issue has been in the news and they don't understand the full
> technical details.  If it makes management feel better to know we do
> not use any SSL certs signed using md5, then verify for me that we
> don't use any certs signed with md5.  I don't care if it actually
> helps or not, it makes management happy and guess who signs *MY*
> check?
>
> Also, this is not MY place of business that is having the issue.  This
> is an issue being experienced by friends in the industry.  I was
> merely looking for a way to help them verify if they had any certs
> that fell into the "concerning" category.

Hi MadHat,

I apologize if the tone of my previous email came across as rude or
short-sided.  My intention was not to argue against writing a SSL+MD5
detection NSE script, it was specifically meant to argue against the
idea that there is a safe way to use MD5 signatures on SSL certs.

As another developer pointed out privately, it would be nice for admins
to know that they are handing out MD5 signed certs so that they can be
"part of the solution" by replacing their certs.  I fully agree with
this point.

Lets be clear though, we are talking about a script to
facilitate /auditing/, not a script that facilitates any
real /security/.

Brandon

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