Re: [yam] [secdir] secdir review of draft-ietf-yam-rfc1652bis-03

Alexey Melnikov <alexey.melnikov@isode.com> Sun, 07 March 2010 12:28 UTC

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Date: Sun, 07 Mar 2010 12:27:40 +0000
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Subject: Re: [yam] [secdir] secdir review of draft-ietf-yam-rfc1652bis-03
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Dave CROCKER wrote:

> On 3/6/2010 11:05 PM, S Moonesamy wrote:
>
>> The Last Call for draft-ietf-yam-rfc1652bis-03 ended yesterday. There 
>> wasn't
>> any comments. This I-D will be evaluated by the IESG on March 11. I am
>> waiting for a recommendation from Dave regarding the Secdir review.
>
> Folks,
>
> Feeling no strong resolve, myself, here's my current though:
>
> The relevant part of Steve Kent's review:
>
>> I could imagine security issues that might be associated with this 
>> document
>> vs. 5321, since the security section of the latter document does not 
>> address
>> any security concerns related to transfer of 8-bit data. For example, 
>> the
>> handshake used to determine whether an SMTP sever support 
>> receipt/relay of
>> 8-bit data might be used to target servers based on the lack of such 
>> support.
>> One might even cite the use of this transport capability as facilitating
>> malware transmission in e-mail attachments :.
>
> A Security section should cover security issues that are specific to that
> specification; it should not contain general-purpose tutorial material 
> nor
> should it contain material that is needed for other specification.  It 
> other words, it should cover security issues that are new.
>
> I suppose there is a reasonable case to be made for some coverage of 
> materials that /should/ have been covered in another document, but 
> weren't, and are relevant to the current specification.  But even that 
> concession makes the question of what to include a slippery slope, IMO.
>
> In any event...
>
> The 8bitmime option does not create the potential for using SMTP option
> negotations as an attack vector, such as permitting discovery of which 
> servers support an option.  I therefore think it better /not/ to cite 
> that in 1652bis. Given that this style of attack is not mentioned 
> elsewhere, I suppose a small enhancement to the current text would be 
> reasonable, such as:
>
>    is not believed to
>    raise any security issues not already endemic in electronic mail and
>    present in fully conforming implementations of [RFC5321] {{ , 
> including
>    attacks facilitated by the presence of an option negotiation 
> mechanism.}}

Works for me.

> Even though 8bitmime is not a pure 'binary' mechanism, it does move 
> things into a binary realm.  I therefore think that it /is/ reasonable 
> to cite the potential for facilitating attacks based on use of binary 
> data.  Hence, I propose also adding the text:
>
>    Exploitation by malware is facilitated by supporting binary data in 
> the
>    transfer.  The 8BITMIME option does not provide a pure binary 
> transport, but
>    since it does transfer a nearly-binary object, there is some 
> possibility
>    that is could facilitate exploitations of this type.

I am not convinced this is needed, as I would like to better understand 
what the issue is. However I also like detailed Security Considerations 
sections so I wouldn't object to adding this text either.

BTW, Arnt and myself explained to Stephen Kent the difference between 
8BITMIME and BINARYMIME. So I think he now understands that 8BITMIME is 
not appropriate for sending arbitrary binary data.

> Anyone object, suggest different text, or additional text?