Re: [Simple] <note> in IMDN

[Eric Burger <eburger at sipforum.org>]

Don't forget the last little bit: not only does it open a vector for  
delivering a spam payload, but it has no value in the white hat case.

On May 29, 2008, at 12:41 PM, Dean Willis wrote:

>
> On May 25, 2008, at 7:57 AM, Eric Burger wrote:
>
>> Almost all of the fields in IMDN are verbatim copies of the IM, which
>> means an automaton can filter spoofed IMDN's.  Just about all of the
>> fields have some protocol semantic value.  However, the <note> field
>> is a spam delivery vector that has no protocol value.  That is my
>> issue with it: no value *and* a method to introduce spam.  That does
>> not sound like a winning combination.
>
> A lot of the spam on the IETF servers comes from forged "bounce"  
> messages. If a message looks like a bounce sent in response to a  
> message that might have come from the IETF list, it is very  
> difficult to weed out. For example, as sip-owner, I get a couple of  
> hundred forged bounce spams a day. Does IMDN share this property? It  
> feels to me like it might. Now personally, I wanted IMDN totally  
> banned from the deliverables; it has proven to be a nightmare in the  
> email world, and I bet it is going to cause us grief. But if we must  
> do it, let's make it as safe as possible.
>
> The unconstrained MIME body is a related problem. Since it is there  
> in an IMDN, it could be populated with stuff of the sender's choosing.
>
> Much more so than some arbitrary quoted-string in a SIP header, a  
> MIME note body (just like a MIME message body) is likely to get  
> parsed out and handed over to the OS-registered handler for the  
> associated MIME type. Many of those handlers have security flaws.
>
> So are we building an attack vector that can't readily be stopped by  
> spam-defense techniques and that is likely to result in malicious  
> code execution? Just how smart is that?
>
> --
> Dean
>
>
>

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