Re: [TLS] TLS Impact on Network Security draft updated

[Flemming Andreasen <[e-mail]>]

On 7/23/19 4:05 PM, Tony Arcieri wrote:
> On Sun, Jul 21, 2019 at 6:51 AM Nancy Cam-Winget (ncamwing) 
> <ncamwing@cisco..com <mailto:[e-mail]>> wrote:
>
>     Hi,
>
>     Thanks to all the feedback provided, we have updated the
>     https://tools.ietf.org/html/draft-camwinget-tls-use-cases-04
>
>     draft. At this point, we believe the draft is stable and would
>     like to request its publication as an informational draft.
>
>
> I read this draft as the latest attempt in a disinformation campaign 
> by manufacturers and users of middleboxes that passively decrypt TLS 
> connections to politicize and reframe the argument around what is, at 
> its core, a fundamentally insecure practice which is incompatible with 
> technically sound and highly desirable protocol improvements to TLS.
>
> I implore you stop using overly broad terminology, euphemisms, weasel 
> words, and other deceptive language to argue your points.
>
I am not a mind-reader, so I will refrain from attributing malice to 
your choice of words - I would appreciate it if you would extend the 
same courtesy.

> This draft is titled "TLS 1.3 Impact on Network-Based Security", but 
> the subtext is quite clearly the much narrower subfield of middlebox 
> TLS decryption. By using such a grandiose title which is deceptively 
> hiding the true subject matter, you are implying that middleboxes are 
> the sum total of network security.
No such implication is intended - we will look for a more accurate 
document title.
>
> The draft begins "Enterprises [...] need to defend their information 
> systems from attacks originating from both inside and outside their 
> networks." I am co-owner of a company which heavily leverages 
> firewalls for layer 3/4 network security in conjunction with TLS. We 
> care deeply about network security, and believe that our network is 
> *more secure* specifically because we *don't* perform middlebox 
> interception of TLS.
>
> I consider our company to be in the category of enterprise TLS users, 
> and as an enterprise TLS user who cares deeply about network security, 
> I do not identify whatsoever with the claims this draft is making 
> about the needs of enterprise TLS users as a whole. In as much as what 
> it describes to "network security", it is but one niche consideration 
> within a vastly broader field, and one which is increasingly 
> controversial.
>
It is indeed controversial, and different enterprises have different 
views on these. I know this because I regularly interact with a number 
of these across different industries.

> I will point out, since you appear to work at Cisco, that your company 
> works on approaches to network security (e.g. malware detection) which 
> avoid decrypting TLS:
>
> https://blogs.cisco.com/security/detecting-encrypted-malware-traffic-without-decryption
>
I am quite familiar with this. Please note that it does not provide a 
full replacement for all existing capabilities

> There is an entire world of network IDS systems beyond middleboxes 
> which passively decrypt TLS.
>
Are you saying that it is possible to passively decrypt TLS 1.3 sessions 
without being a MITM (or otherwise sharing keying material) ?

> It is factually inaccurate for this draft to be described as "TLS 1.3 
> Impact on Network-Based Security". If you are going to write a draft 
> about the impact of TLS 1.3 on middleboxes for passive TLS decryption, 
> please call a spade a spade and don't try to hide your true intentions 
> under a bunch of weasel words and overly broad claims that make it 
> sound like middlebox-related TLS decryption problems are the end of 
> network security as we know it.
>
> My 2c, on behalf of non-middlebox-using enterprise TLS users who feel 
> that attempts by middlebox-using enterprise TLS users to weaken TLS in 
> order to retain compatibility with their traffic decryption appliances 
> is a threat to the security of our enterprise TLS deployments.
Please see my earlier comments on this.

Thanks

-- Flemming

>
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