Re: Security Assessment of the Transmission Control Protocol (TCP)

[Lars Eggert <[e-mail]>]

Hi,

On 2009-2-14, at 0:25, Marshall Eubanks wrote:
> If I am reading this correctly the UK Centre for the Protection of
> National Infrastructure
> wants the IETF (or some other body) to produce a "companion document
> to the IETF specifications that discusses the security aspects and
> implications of the protocols, identifies the existing
> vulnerabilities, discusses the possible countermeasures, and analyses
> their respective effectiveness."


during the discussions around the TCP implementation deficiencies  
publicized by the Outpost24 last fall, we discussed with CERT-FI and  
others in that community that the IETF would offer to be the venue for  
publishing such a document. The goal would be to document techniques  
that stack vendors are employing to harden their stacks. They asked us  
to wait until vendors had a chance to deploy patches to the latest  
round of vulnerabilities, and we haven't heard back from them since  
late last year. (Which reminds me to shoot them an email.)

I believe such a document would be fully in scope for TCPM, but  
obviously the involvement of the stack vendors is critical to ensure  
this is a document that has practical relevance.

Lars

> Begin forwarded message:
>
>> From: Fernando Gont <[e-mail]>
>> Date: February 12, 2009 5:38:35 PM EST
>> To: [e-mail], [e-mail]
>> Subject: Security Assessment of the Transmission Control Protocol
>> (TCP)
>>
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA256
>>
>> Hello, folks,
>>
>> The United Kingdom's Centre for the Protection of National
>> Infrastructure has just released the document "Security Assessment of
>> the Transmission Control Protocol (TCP)", on which I have had the
>> pleasure to work during the last few years.
>>
>> The motivation to produce this document is explained in the Preface  
>> of
>> the document as follows:
>>
>> - ---- cut here ----
>> The TCP/IP protocol suite was conceived in an environment that was
>> quite
>> different from the hostile environment they currently operate in.
>> However, the effectiveness of the protocols led to their early
>> adoption
>> in production environments, to the point that to some extent, the
>> current world?s economy depends on them.
>>
>> While many textbooks and articles have created the myth that the
>> Internet protocols were designed for warfare environments, the top
>> level
>> goal for the DARPA Internet Program was the sharing of large service
>> machines on the ARPANET. As a result, many protocol specifications
>> focus
>> only on the operational aspects of the protocols they specify, and
>> overlook their security implications.
>>
>> While the Internet technology evolved since it early inception, the
>> Internet?s building blocks are basically the same core protocols
>> adopted
>> by the ARPANET more than two decades ago.
>>
>> During the last twenty years, many vulnerabilities have been
>> identified
>> in the TCP/IP stacks of a number of systems. Some of them were based
>> on
>> flaws in some protocol implementations, affecting only a reduced
>> number
>> of systems, while others were based in flaws in the protocols
>> themselves, affecting virtually every existing implementation. Even  
>> in
>> the last couple of years, researchers were still working on security
>> problems in the core protocols.
>>
>> The discovery of vulnerabilities in the TCP/IP protocol suite usually
>> led to reports being published by a number of CSIRTs (Computer
>> Security
>> Incident Response Teams) and vendors, which helped to raise awareness
>> about the threats and the best mitigations known at the time the
>> reports
>> were published. Unfortunately, this also led to the documentation of
>> the
>> discovered protocol vulnerabilities being spread among a large
>> number of
>> documents, which are sometimes difficult to identify.
>>
>> For some reason, much of the effort of the security community on the
>> Internet protocols did not result in official documents (RFCs) being
>> issued by the IETF (Internet Engineering Task Force). This basically
>> led
>> to a situation in which ?known? security problems have not always
>> been addressed by all vendors. In addition, in many cases vendors  
>> have
>> implemented quick ?fixes? to the identified vulnerabilities without a
>> careful analysis of their effectiveness and their impact on
>> interoperability.
>>
>> Producing a secure TCP/IP implementation nowadays is a very difficult
>> task, in part because of the lack of a single document that serves
>> as a
>> security roadmap for the protocols. Implementers are faced with the
>> hard
>> task of identifying relevant documentation and differentiating  
>> between
>> that which provides correct advice, and that which provides  
>> misleading
>> advice based on inaccurate or wrong assumptions.
>>
>>
>> There is a clear need for a companion document to the IETF
>> specifications that discusses the security aspects and implications  
>> of
>> the protocols, identifies the existing vulnerabilities, discusses the
>> possible countermeasures, and analyses their respective  
>> effectiveness.
>>
>> This document is the result of a security assessment of the IETF
>> specifications of the Transmission Control Protocol (TCP), from a
>> security point of view. Possible threats are identified and, where
>> possible, countermeasures are proposed. Additionally, many
>> implementation flaws that have led to security vulnerabilities have
>> been
>> referenced in the hope that future implementations will not incur the
>> same problems.
>>
>> This document does not aim to be the final word on the security
>> aspects
>> of TCP. On the contrary, it aims to raise awareness about a number of
>> TCP vulnerabilities that have been faced in the past, those that are
>> currently being faced, and some of those that we may still
>> have to deal with in the future.
>>
>> Feedback from the community is more than encouraged to help this
>> document be as accurate as possible and to keep it updated as new
>> vulnerabilities are discovered.
>> - ---- cut here ----
>>
>> The document is available at CPNI's web site:
>> http://www.cpni.gov.uk/Products/technicalnotes/Feb-09-security-assessment-TCP.aspx
>>
>> Additionally, I have posted a copy of the document on my personal web
>> site: http://www.gont.com.ar
>>
>> Any comments will be more than welcome.
>>
>> Kind regards,
>> - --
>> Fernando Gont
>> e-mail: [e-mail] || [e-mail]
>> PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1
>>
>>
>>
>>
>>
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>
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