Re: SCRAM with channel binding downgrade attack

On 6/6/18 16:26, Heikki Linnakangas wrote:
> On 06/06/18 23:20, Peter Eisentraut wrote:
>> Aren't we attacking this on the wrong level?  We are here attempting to
>> prevent a SCRAM-SHA-256-PLUS -> SCRAM-SHA-256 downgrade, but we are not
>> preventing a SCRAM-SHA-256-PLUS -> anything-else downgrade.
> 
> The latest patch does prevent that, too. That was my complaint at 
> https://www.postgresql.org/message-id/030284cc-d1d6-ce88-b677-a814f61c1880%40iki.fi, 
> but it's been fixed now. (Or if you see a case where it still isn't, 
> that's a bug.)

OK, that would do, but we don't do anything about a SCRAM-SHA-256 ->
anything-else downgrade.  Instead of tying this to the channel binding,
should we tie it to the authentication type?

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
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