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Re: ssf Security Question



William Brown wrote:
On Fri, 2017-11-17 at 08:34 +0100, Michael Ströder wrote:
William Brown wrote:
Just want to point out there are some security risks with ssf
settings.
I have documented these here:

https://fy.blackhats.net.au/blog/html/2016/11/23/the_minssf_trap.ht
ml

Nice writeup. I always considered SSF values to be naive and somewhat
overrated. People expect too much when looking at these numbers -
especially regarding the "strength" of cryptographic algorithms which
changes over time anyway with new cryptanalysis results coming up.

Personally I always try to implement a TLS-is-must policy and prefer
LDAPS (with correct protocol and ciphersuites configured) over
LDAP/StartTLS to avoid this kind of pre-TLS leakage.
Yes, I deliberately ignore "LDAPS is deprecated". ;-]

I agree. If only there was a standards working group that could
deprecate startTLS in favour of TLS .... :)

I have to agree as well. On my own servers I also use TLS on other "plaintext" ports too (such as pop3 and others) that no one has any business connecting to in plaintext.

Furthermore some LDAP server implementation (IIRC e.g. MS AD) refuse
to
accept SASL/GSSAPI bind requests sent over TLS-secured channel. Which
is
IMO also somewhat questionable.

Yes, I really agree. While a plain text port exists, data leaks are
possible. We should really improve this situation, where we have TLS
for all data to prevent these mistakes.

I think a big part of the issue is that GSSAPI forces the encryption
layer, and can't work via an already encrypted channel. The people I
know involved in this space are really resistant to changing this due
to the "kerberos centric" nature of the products.

Interesting. Our libldap/liblber works fine with GSSAPI's encryption layered over TLS and vice versa.

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