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Re: [Simple] <note> in IMDN



I cannot argue with that position :-)
+1

On Sep 16, 2008, at 9:24 PM, Hisham Khartabil wrote:

For the sake of moving this draft to completion, I plan to remove the <note> element from IMDNs. If someone is interested in extending the schema to allow an element that carries extra information about the reasons behind a certain disposition status, please write an I-D.

Any objections?

Regards,
Hisham


On 04/06/2008, Eric Burger <eburger at standardstrack.com> wrote: Except:

1. I have no clue what language to use in the message, as a human will read it.

2. The field is free-form, so is not amenable for automaton processing.

3. The field is free-form, but could be read by the UAC, so it will invite vendors to put proprietary information into the field. Then users expect particular behaviors when these values are present. I.e., who needs the IETF to review protocol element use? Let the random implementor of the day build a protocol on top of IMDN!

4. The field is free-form and displayed to the user, so it will invite spam.

If it is useful from a protocol perspective, then create an IANA registry of values.



On Jun 4, 2008, at 5:19 AM, Hisham Khartabil wrote:

The field is not useless. It carries extra information (a reason
phrase, if you like) as to why the IM delivery resulted in an error or
still being processed, etc.

Hisham

2008/6/4 Ben Campbell <ben at estacado.net>:

On May 23, 2008, at 2:21 PM, Eric Burger wrote:

Actually, IMDNs, even the SIMPLE free-form fields, are fairly
constrained.  Any mis-match is an opportunity to filter out bad
IMDNs.  The <note> field has three problems:

1. It cannot be filtered, as any content could be real (which
introduces the attack vector)

2. It cannot know what language it should use, and thus is not likely
to be useful to the recipient

3. It has no protocol value, and is of no value to the UA


So, if something has no useful protocol value and introduces a spam
opportunity, why would we want to include it?


If something has no useful protocol value, even if it _does_no_harm,
why would we want to include it?

IMHO, there is no need to prove a vector for harm, if we are fairly
certain there is no vector for _utility_.

(Note that I am agnostic on whether  the field is truly useless--I am
merely commenting on the form of the argument.)




On May 21, 2008, at 7:45 PM, Paul Kyzivat wrote:

Its kind of late to be thinking about this now. THe problem is
pervasive
in MSRP.

In SIP there are lots of unconstrained fields. But they are all
constrained by the overall size of the message, and people commonly
put
limits on that.

In MSRP, because of chunking, a single MSRP message can be gigabytes
long. So using that to bound the unconstrained parts of the headers
doesn't work very well.

A robust implementation might take a similar approach - define its
own
limit on the total message size, excluding the body. Then it could
constrain all the unconstrained fields to fit within it.

But picking on one header isn't a solution to the problem. Either
assume
the developers will be able to deal with it, or else do and MSRPv2
that
eliminates all unconstrained fields.

   Paul

Dean Willis wrote:
On May 13, 2008, at 11:38 PM, Hisham Khartabil wrote:

Can you explain how it is an attack vector?


Unconstrained rich content is one of the most easily exploited
attack
vectors.

Buffer overrun attacks as well as all of the typical MIME compound-
component attacks are likely. For example, the common JPEG
vulnerabilities might be exploitable:

http://www.news.com/Image-virus-spreads-via-chat/2100-7349_3-5390463.html


Or the content-execution weakness that caused the Macintosh Safari
browse to be most easily exploited in recent hacking contests:

http://www.engadget.com/2007/07/23/safari-exploit-gives-hackers-full-control-of-your-iphone/


There have also been exploits against QuickTime, Flash, and most
other
plugin components from time to time.

--
Dean
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