Re: [TLS] Industry Concerns about TLS 1.3

BITS Security <BITSSecurity@fsroundtable.org> Tue, 27 September 2016 18:21 UTC

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From: BITS Security <BITSSecurity@fsroundtable.org>
To: Hugo Krawczyk <hugo@ee.technion.ac.il>
Thread-Topic: [TLS] Industry Concerns about TLS 1.3
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Date: Tue, 27 Sep 2016 18:20:54 +0000
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Subject: Re: [TLS] Industry Concerns about TLS 1.3
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The various suggestions for creating fixed/static Diffie Hellman keys raise interesting possibilities.  We would like to understand these ideas better at a technical level and are initiating research into this potential solution.  We need to understand the potential ramifications and other implementation details.  This solution would have to be implemented in servers, firewalls, load balancers, Internet proxies, and mainframes.  If vendors broadly refuse to support then it is not much a solution but at this point looks like it is worth exploring.  

Really appreciate those who brought this to our attention.  

- Andrew



From: hugokraw@gmail.com [mailto:hugokraw@gmail.com] On Behalf Of Hugo Krawczyk
Sent: Thursday, September 22, 2016 7:41 PM
To: BITS Security <BITSSecurity@fsroundtable.org>;
Cc: tls@ietf.org
Subject: Re: [TLS] Industry Concerns about TLS 1.3

If the problem is the use of forward secrecy then there is a simple solution, don't use it.
That is, you can, as a server, have a fixed key_share for which the secret exponent becomes the private key exactly as in the RSA case. It does require some careful analysis, though.

But maybe I misunderstood the problem and maybe I should not be putting these surveillance-friendly ideas in people's minds...

Hugo




On Thu, Sep 22, 2016 at 1:19 PM, BITS Security <BITSSecurity@fsroundtable.org>; wrote:
To:  IETF TLS 1.3 Working Group Members

My name is Andrew Kennedy and I work at BITS, the technology policy division of the Financial Services Roundtable (http://www.fsroundtable.org/bits).  My organization represents approximately 100 of the top 150 US-based financial services companies including banks, insurance, consumer finance, and asset management firms.

I manage the Technology Cybersecurity Program, a CISO-driven forum to investigate emerging technologies; integrate capabilities into member operations; and advocate member, sector, cross-sector, and private-public collaboration.

While I am aware and on the whole supportive of the significant contributions to internet security this important working group has made in the last few years I recently learned of a proposed change that would affect many of my organization's member institutions:  the deprecation of RSA key exchange.

Deprecation of the RSA key exchange in TLS 1.3 will cause significant problems for financial institutions, almost all of whom are running TLS internally and have significant, security-critical investments in out-of-band TLS decryption.

Like many enterprises, financial institutions depend upon the ability to decrypt TLS traffic to implement data loss protection, intrusion detection and prevention, malware detection, packet capture and analysis, and DDoS mitigation.  Unlike some other businesses, financial institutions also rely upon TLS traffic decryption to implement fraud monitoring and surveillance of supervised employees.  The products which support these capabilities will need to be replaced or substantially redesigned at significant cost and loss of scalability to continue to support the functionality financial institutions and their regulators require.

The impact on supervision will be particularly severe.  Financial institutions are required by law to store communications of certain employees (including broker/dealers) in a form that ensures that they can be retrieved and read in case an investigation into improper behavior is initiated.  The regulations which require retention of supervised employee communications initially focused on physical and electronic mail, but now extend to many other forms of communication including instant message, social media, and collaboration applications.  All of these communications channels are protected using TLS.

The impact on network diagnostics and troubleshooting will also be serious.  TLS decryption of network packet traces is required when troubleshooting difficult problems in order to follow a transaction through multiple layers of infrastructure and isolate the fault domain.   The pervasive visibility offered by out-of-band TLS decryption can't be replaced by MITM infrastructure or by endpoint diagnostics.  The result of losing this TLS visibility will be unacceptable outage times as support groups resort to guesswork on difficult problems.

Although TLS 1.3 has been designed to meet the evolving security needs of the Internet, it is vital to recognize that TLS is also being run extensively inside the firewall by private enterprises, particularly those that are heavily regulated.  Furthermore, as more applications move off of the desktop and into web browsers and mobile applications, dependence on TLS is increasing.

Eventually, either security vulnerabilities in TLS 1.2, deprecation of TLS 1.2 by major browser vendors, or changes to regulatory standards will force these enterprises - including financial institutions - to upgrade to TLS 1.3.  It is vital to financial institutions and to their customers and regulators that these institutions be able to maintain both security and regulatory compliance during and after the transition from TLS 1.2 to TLS 1.3.

At the current time viable TLS 1.3-compliant solutions to problems like DLP, NIDS/NIPS, PCAP, DDoS mitigation, malware detection, and monitoring of regulated employee communications appear to be immature or nonexistent.  There are serious cost, scalability, and security concerns with all of the currently proposed alternatives to the existing out-of-band TLS decryption architecture:

-  End point monitoring: This technique does not replace the pervasive network visibility that private enterprises will lose without the RSA key exchange.  Ensuring that every endpoint has a monitoring agent installed and functioning at all times is vastly more complex than ensuring that a network traffic inspection appliance is present and functioning.  In the case of monitoring of supervised employee communications, moving the monitoring function to the endpoint raises new security concerns focusing on deliberate circumvention - because in the supervision use case the threat vector is the possessor of the endpoint.

-  Exporting of ephemeral keys:  This solution has scalability and security problems on large, busy servers where it is not possible to know ahead of time which session is going to be the important one.

-  Man-in-the-middle:  This solution adds significant latency, key management complexity, and production risk at each of the needed monitoring layers.

Until the critical concerns surrounding enterprise security, employee supervision, and network troubleshooting are addressed as effectively as internet MITM and surveillance threats have been, we, on behalf of our members, are asking the TLS 1.3 Working Group to delay Last Call until a workable and scalable solution is identified and vetted, and ultimately adopted into the standard by the TLS 1.3 Working Group.

Sincerely,

Andrew Kennedy
Senior Program Manager, BITS




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