Re: [TLS] I-D Action: draft-ietf-tls-grease-01.txt

Hubert Kario <hkario@redhat.com> Wed, 13 June 2018 13:46 UTC

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From: Hubert Kario <hkario@redhat.com>
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Date: Wed, 13 Jun 2018 15:46:04 +0200
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Subject: Re: [TLS] I-D Action: draft-ietf-tls-grease-01.txt
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On Saturday, 9 June 2018 03:13:29 CEST Christian Huitema wrote:
> On 6/8/2018 7:35 AM, David Benjamin wrote:
> > On Fri, Jun 8, 2018 at 10:07 AM R duToit <r@nerd.ninja>; wrote:
> >     > GREASE values should not make their way into code. The whole
> >     
> >     point is to get code used to the fact that unknown values exist.
> >     
> >     The GREASE mechanism is useful, but it will definitely make its
> >     way into code and become ossified itself.  
> >     Example:  https://github.com/salesforce/ja3
> > 
> > Indeed. GREASE was targeting normal sensible endpoint implementations...
> 
> ... and maybe we need a different mechanism to defeat fingerprinting
> tools like this JA3 project. Maybe applications need to somehow
> randomize their signatures, so that they are not so easy to recognize.
> For example, it should be possible to use randomize the order of
> extensions. And it should also be possible to throw some grease in these
> sets.
> 
> Of course, the first ones to develop and use these randomization
> techniques will most likely be the malware authors that the tools are
> allegedly trying to track.

you can probe implementations irrespective of enabled ciphers, just by looking 
at the way they handle errors:
https://github.com/WestpointLtd/tls_prober

-- 
Regards,
Hubert Kario
Senior Quality Engineer, QE BaseOS Security team
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purky┼łova 115, 612 00  Brno, Czech Republic