Horton

SCRAM with channel binding downgrade attack

Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

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From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
To: Magnus Hagander <magnus@hagander.net>, Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Bruce Momjian <bruce@momjian.us>, Michael Paquier <michael@paquier.xyz>, Robert Haas <robertmhaas@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Postgres hackers <pgsql-hackers@postgresql.org>, Stephen Frost <sfrost@snowman.net>
Date: 2018-06-28T08:05:47Z
Lists: pgsql-hackers 
On 6/28/18 09:35, Magnus Hagander wrote:
> No, we absolutely still have SCRAM channel binding.
> 
> *libpq* has no way to *enforce* it, meaning it always acts like our
> default SSL config which is "use it if available but if it's not then
> silently accept the downgrade". From a security perspective, it's just
> as bad as our default ssl config, but unlike ssl you can't configure a
> requirement in 11.

Isn't this similar to what happened whenever we added a new or better
password method?  A MITM that didn't want to bother cracking MD5 could
just alter the stream and request "password" authentication.  Same with
MD5->SCRAM, SCRAM->SCRAM+CB, and even a hypothetical future change in
the SCRAM hashing method.  Clearly, we need a more comprehensive
solution for this.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. doc: update PG 11 release notes

  2. Fix misspelled pg_trgm contrib name in PostgreSQL 11 release notes

  3. Doc: clarify release note text about v11's new window function features.

  4. Improve wording of release notes item

  5. Fix typos in release notes

  6. Doc: preliminary list of PG11 major features.

  7. Make numeric power() handle NaNs according to the modern POSIX spec.

  8. Various improvements of skipping index scan during vacuum technics

  9. Revert back-branch changes in power()'s behavior for NaN inputs.

  10. Avoid wrong results for power() with NaN input on more platforms.

  11. Avoid wrong results for power() with NaN input on some platforms.

  12. Skip full index scan during cleanup of B-tree indexes when possible

  13. Rewrite the code that applies scan/join targets to paths.

  14. Postpone generate_gather_paths for topmost scan/join rel.

  15. Add casts from jsonb

  16. Make plpgsql use its DTYPE_REC code paths for composite-type variables.

  17. Don't allow VACUUM VERBOSE ANALYZE VERBOSE.

  18. Pass InitPlan values to workers via Gather (Merge).

  19. Account for the effect of lossy pages when costing bitmap scans.

  20. Allow no-op GiST support functions to be omitted.

  21. Rearm statement_timeout after each executed query.

  22. Push limit through subqueries to underlying sort, where possible.