Re: disable TLS compression with openssl?

[Howard Chu <hyc@symas.com>]

Dieter Klünter wrote:
> Am Sun, 06 Dec 2015 19:27:31 -0800
> schrieb "Paul B. Henson" <henson@acm.org>:
>
> > We're currently running through all of our SSL/TLS using apps to
> > disable SSLv3 and update the accepted ciphers list, as well as other
> > current best practices. I don't see any way to disable SSL
> > compression in openldap?

OpenLDAP does not enable compression so there is nothing to disable.

> > Does SSL compression with ldap traffic not
> > lead to the same issue as it does in web traffic?

No, it does not have the same issue. The CRIME attack works because http is a 
stateless protocol and so clients repeatedly send their 
authentication/authorization credentials in cookies attached to every request. 
In particular, the exact format of each request is known and it's trivial to 
create a request with plaintext chosen to guess at the credential portion.

The CRIME attack does not work against LDAP or other stateful protocols where 
credentials are only sent once.

> You probabely should read
> https://community.qualys.com/blogs/securitylabs/2012/09/14/crime-information-leakage-attack-against-ssltls
> https://www.openssl.org/docs/manmaster/ssl/SSL_COMP_add_compression_method.htm
>
> > Also, are there any plans to support ECDHE ciphers in openldap? I see
> > there's an ITS ticket about it, it's rather old and the last update
> > questioned whether those ciphers should be avoided due to potential
> > NSA meddling in their design.
>
> At LDAPcon 2015 it was announced to be included in OpenLDAP-2.5
>
> -Dieter


--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/