Re: [Idr] WG Adoption call for draft-snijders-idr-shutdown (11/16 to 11/30)

I understand people may want the characters in their language, but is there
a technical reason for UTF-8, like many of you I've worked with many
engineers, in ehe past 20 years,for who english is not their native
language. I suspect many of those of you that know me have questioned if it
is mine :)  However  these engineers typically, while thinking in their
first language, "work" in english, as its the defacto standard, much like
with air travel.

-jim

On Mon, Nov 21, 2016 at 12:54 PM, Job Snijders <job@ntt.net> wrote:

> On Sun, Nov 20, 2016 at 08:04:54PM +0000, Martin Hannigan wrote:
> > This is useful. On the security considerations, I’m having a little
> > bit of a fail grokking what visual spoofing means in this case? Is
> > there way to spoof a cease message from a third party and create a
> > message like “tear down, gone forever” in an unsecured (not MD5 or
> > other secured mechanism) or is the reference to UTR36 more perfunctory
> > and along the lines of “don’t send money to someone sending a request
> > in this message including example@sample.com as a target address?
>
> Visual spoofing exists in (at least) two forms, one is on the character
> level: where innocuous characters are replaced with variants for
> nefarious purposes, for example the following look alike but are
> different: Greek Ο, Latin O, and Cyrillic О. The other variant is where
> somehow a newline, newpage, feedpage or enough spaces to wrap the line
> are inserted, and the receiving side might incorrectly think there are
> more than 1 syslog messages where in reality its just 1 message,
> containing a communication + syslog-like content.
>
> To counter this the length of the string is limited to be very brief. If
> one is allowed to insert say 4000 bytes worth of Shutdown Communication,
> you could easily 'visually spoof' half a page worth of fake-syslog. The
> receiving side might think his/her router is in big trouble and perform
> an emergency reboot or upgrade based on false information.
>
> Further reading: (search bing.com for 'visual spoofing')
>
>     https://en.wikipedia.org/wiki/IDN_homograph_attack
>     http://unicode.org/reports/tr36/#visual_spoofing
>
> Another defense is to squash likely garbage and not print that. So one
> should replace the garbage with U+FFFD "replacement character" so that
> "drÃ£Â©op table XXX;" becomes "dr�op table XXX;" and not "drop table
> XXX;". The next version of the draft will provide more guidance on that.
>
> This draft is breaking a lance for IDR in that it is the first draft (as
> far as I know) to carefully consider the security aspects of using UTF-8
> at this level.
>
> I think UTF-8 is the right choice, it can be done (many industries have
> gone before us), there is more than Roman script in this world, but
> we'll need to make implementors aware.
>
> > Any real concern over buffer overflows?
>
> The clearly defined upperbound length of the BGP PDU, the Cease
> NOTIFICATION and the length marker for the Shutdown Communication itself
> can help mitigate these. I don't think there are any real new
> considerations here. Normal printf, strlcpy, strlcat recommendations
> apply. It was an explicit choice to not use a NUL-termination.
>
> I welcome feedback from others, I wouldn't dare to proclaim I'm anything
> close to an expert.
>
> Kind regards,
>
> Job
>
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