On 08.01.2010 07:11, Kyle Hamilton wrote:
On Thu, Jan 7, 2010 at 5:20 PM, Lou Picciano<[email protected]> wrote:
Kyle,
Meanwhile, as we now gird our loins for the impending reversion of many big
apps on our servers (only to re-implement updates when openSSL 0.0.8m
becomes available!), is there any tweaking of a simple SSL-enabled Apache
/Directory we might be able to do to bypass the renegotiation? I'm
anticipating your answer to be 'no', as a renegotiation is required at load
of any object in the site, correct?
Many thanks in advance. Lou
I honestly don't know. You would do better asking on an Apache
support list, I think; most of us don't know the Apache codebase (or
mod_ssl's requirements on the library) at all.
I *think* you might be able to do it at a /VirtualHost level, for the
https server, as long as you get rid of any SSL configuration
statements (other than SSLRequire SSL) in the /Directory clauses.
(Use the highest security you need, and disable renegotiation.)
The SSL renegotiation insecurity has two aspects, namely client
initiated renegotiation and server initiated renegotiation. Both of them
can be used by a man in the middle as an attack vector.
Renegotiations are needed for an Apache https configurations only, if
you have a complex SSL configuration that has various different SSL
requirements in the same vhost, like requiring client certs only for
some Directory, or changing the allowed cipher specs for some Directory
(or Location).
If you do not use such a configuration, the best and at the moment only
way to be safe against the attack is upgrading to OpenSSl 0.9.8l.
There is a patch for Apache 2.2.14 which completely disables client
initiated renegotiation thereby still allowing server side renegotiation:
http://www.apache.org/dist/httpd/patches/apply_to_2.2.14/
This makes you safe from (only) one half of the attack without an
OpenSSL upgrade and still allows the complex configs to work. An
enhancement of this patch which should prevent all server side
renegotiation attacks known at the moment has been applied to the 2.2.x
branch very recently:
http://svn.apache.org/viewvc?rev=896900&view=rev
The first patch has been backported and suggested for 2.0:
http://svn.apache.org/viewvc?view=revision&revision=882861
http://people.apache.org/~rjung/patches/cve-2009-3555_httpd_2_0_x-v2.patch
and for 1.3:
http://www.mail-archive.com/[email protected]/msg17939.html
A backport for the second patch does not yet exist.
I think further discussion about Apache specific question are a better
fit for the Apache httpd users list.
Regards,
Rainer
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