Re: [TLS] draft-green-tls-static-dh-in-tls13-01

Martin Thomson <martin.thomson@gmail.com> Wed, 12 July 2017 01:39 UTC

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From: Martin Thomson <martin.thomson@gmail.com>
Date: Wed, 12 Jul 2017 11:39:24 +1000
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To: Steve Fenter <steven.fenter58@gmail.com>
Cc: Stephen Farrell <stephen.farrell@cs.tcd.ie>, "tls@ietf.org" <tls@ietf.org>
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Subject: Re: [TLS] draft-green-tls-static-dh-in-tls13-01
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On 12 July 2017 at 09:59, Steve Fenter <steven.fenter58@gmail.com>; wrote:
>> And if you had one an estimate for how much malware does it's own
>> obfuscation or home-grown crypto in addition or instead of using TLS.
>> The reason to ask is that as soon as malware does that then you
>> are back to analysis based on ciphertext only. From descriptions
>> of advanced attack schemes, they do seem to do both when calling
>> home or exfiltrating data. In which case I think your argument
>> falls.
>
> I don't have any numbers for home-grown crypto.  I would think the odds are better for the enterprise if they can decrypt and inspect whatever portion is TLS.

Wouldn't malware avoid connecting to servers that offer the wrong
credentials?  Implementing elementary key pinning or overriding trust
anchors is pretty trivial - it's a feature that enterprises frequently
rely on after all.