Re: [TLS] Broken browser behaviour with SCADA TLS

Hubert Kario <hkario@redhat.com> Tue, 10 July 2018 12:45 UTC

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From: Hubert Kario <hkario@redhat.com>
To: =?ISO-8859-1?Q?Bj=F6rn?= Haase <bjoern.haase@conducta.endress.com>
Cc: Peter Gutmann <pgut001@cs.auckland.ac.nz>, "tls@ietf.org" <tls@ietf.org>
Date: Tue, 10 Jul 2018 14:45:05 +0200
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Subject: Re: [TLS] Broken browser behaviour with SCADA TLS
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On Tuesday, 10 July 2018 08:47:15 CEST Björn Haase wrote:
> > Peter Gutmann wrote:
> >In addition, the security doesn't have to be theoretically perfect, just
> >good enough.  An isolated network is frequently deemed secure enough,
> Mostly in my analysis the assumption of the "isolation" of the network is a
> security-misconception making setups vulnerable. You just need a network
> plug and an own wireless device for making the plant remotely vulnerable.
> While I agree that in most cases permanent physical access to a plant by an
> attacker is unlikely, I consider it clearly feasible for the adversary to
> have short-time access to an installation.

exactly, and plopping down an Ethernet to M2M gateway is something that will 
require access once and doesn't even require a knowledgeable attacker (variant 
of Evil Maid attack essentially)

> >(16-bit device, and it took about 30s for the connection to be established,
> >the key size was chosen because it was all the hardware could handle).
> BTW, This is actually why we in the ICS business need TLS1.3 with its fast
> options on tiny devices such as X25519 and Ed25519. That's by integer
> factors faster on devices such as the M0 or the MSP430 than all of the
> fastest legacy options, such as P256!
> 
> Yours,
> 
> Björn
> 
> P.S.:
> 
> Also in my perception, we clearly need a PAKE option for ICS use, both as
> replacement for PSK for machine2machine interfaces and for true
> operator-account logins. We currently cannot to rely on a properly
> installed PKI in ICS environments.

given what you said above, it sounds to me, like the PAKE in question should 
use negotiation for group (curve) selection, wouldn't it?

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