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* [TUHS] attachments: MIME and uuencode
@ 2017-03-12 18:13 Doug McIlroy
  2017-03-12 18:22 ` Larry McVoy
                   ` (2 more replies)
  0 siblings, 3 replies; 38+ messages in thread
From: Doug McIlroy @ 2017-03-12 18:13 UTC (permalink / raw)


Allowing more or less arbitrary attachments was a real convenience.
But allowing such stuff to serve as the message proper was 
dubious at best. Not only did it require recipients to obtain
special software to read some messages; it also posed a
security threat. 

I still use mailx precisely because it will only display plain text.
With active text such as HTML, it is all too easy to mistakenly
brush over a phishing link. Outfits like Constant Contact do their
nonprofit clients a disservice by sending stuff that I won't even
peek at. And it's an annoying chore when companies I actually want
to deal with send receipts and the like in (godawful) HTML only.

Doug


^ permalink raw reply	[flat|nested] 38+ messages in thread
* [TUHS] attachments: MIME and uuencode
@ 2017-03-12 20:04 Noel Chiappa
  2017-03-12 21:34 ` Random832
  0 siblings, 1 reply; 38+ messages in thread
From: Noel Chiappa @ 2017-03-12 20:04 UTC (permalink / raw)


    > From: Doug McIlroy

    > Allowing more or less arbitrary attachments was a real convenience. But
    > allowing such stuff to serve as the message proper was dubious at
    > best.

Sorry, I'm not sure I'm completely clear what you mean there? Do you mean
'non-ASCII-text objects were processed by the mail system without being told
to do so explicitly, by the user'? That, combined with the below, is indeed a
problem.

    > it also posed a security threat.

The problem isn't really so much the ability to have attachments, as that
people defined attachment types with open-ended capabilities, up to and
including what I call 'active content' - i.e. content which includes code
which is to be run.

(Yes, yes, I know - even without that, it's possible to feed 'dumb'
applications bad data, and do an intrusion; I seem to recall there was one of
those with JPEG's, so even plain images were not perfectly safe.  And someone
just provided an example of an with plain ASCII. But those holes are much
harder to find/use, whereas active content is a security hole the size of a
trans-Atlantic liner.)

Without an _incredibly_ secure OS (something on the order of late-stage
Multics, when the security had been beefed up even over the original design
[the jargon to search for is 'AIM', if you're interested], or better),
bringing in 'active content' from _outside_ the system, and running it, is
daylight madness - it's an invitation to disaster.

This is true no matter _how_ such content comes in: via HTTP, with a Web
browser; via SMTP, with e-mail, whatever.

Dave Moon coined a phrase, based on an old anti-drug movie: 'TECO madness: A
moment of convenience, a lifetime of regret.' These active contents all, to
me, fall into that category. They _seem_ like a good idea, and provide
interesting capabilities - until some cracker uses one to wipe your hard
drive.


    > With active text such as HTML, it is all too easy to mistakenly brush
    > over a phishing link.

HTML email is another of my pet peeves/hot buttons - it's just another vector
for active conent. So, for the 'convenience' of being able to send email in
multiple fonts ('eye candy', I derisively call it), we get to let malefactors
send in viruses that can wipe a hard drive.

To me, this kind of thing is professional malpractice, on a par with building
cars that catch on fire, or buildings that collapse. People need to suffer
incredibly severe penalties for propogating this kind of nonsense; maybe then
software engineers will stop valuing convenience over regret.

       Noel


^ permalink raw reply	[flat|nested] 38+ messages in thread
* [TUHS] attachments: MIME and uuencode
@ 2017-03-12 18:57 Andy Valencia
  0 siblings, 0 replies; 38+ messages in thread
From: Andy Valencia @ 2017-03-12 18:57 UTC (permalink / raw)


> Back in the day plain ASCII wasn't really secure, either.

No need to use the past tense.  I had a need to assess how much
damage one could do if allowed to feed arbitrary text into xterm.
I came away sobered.

Do not--ever--use a mail agent which will plumb unfiltered text
through to an xterm.  nmh, for one:

    http://savannah.nongnu.org/bugs/?36056

Andy


^ permalink raw reply	[flat|nested] 38+ messages in thread
* [TUHS] attachments: MIME and uuencode
@ 2017-03-12 15:10 Noel Chiappa
  0 siblings, 0 replies; 38+ messages in thread
From: Noel Chiappa @ 2017-03-12 15:10 UTC (permalink / raw)


    > From: Dan Cross

    > why did you consider it such a step forward? I'm really curious about
    > the reasoning from folks involved with such things at the time.

This was N layers up from my zone of responsibility when I was on the IESG
(which was the internetwork layer), and I don't recall any discussion about it
on the IESG (although if you really care, there might be minutes - I don't
recall when IESG minutes started, though, perhaps this was before that). That
lack of any memory may be nothing more than a sign of my fading memory, but it
could mean it wasn't a very contentious topic.

FWIW, here's my current analysis of the issues; I doubt my analysis then
would have been substantially different.


The fundamental thing that email does is send something - originally a
section of text - from party A to party B in a way that requires no previous
setup or interaction: party B can be anyone in the entire universe of
entities which support that service. MIME is an extension of this model to
carry other types of data: images, etc.

There is a very good analogy to the pre-existing real-world mail system: that
too allows one to send things to anyone without prior special arrangement, and
it supports not only transferring text, but also sending more than that -
physical objects. This pre-existing system argues that this model of operation
is i) useful, and ii) issues raised by it have probably mostly been worked
through.

So the extension of email to carry more than just text seems like a very
plausible extension.

For the 'average' user, the ability to include images in email is a huge
improvement over any alternative. Any kind of 'pull' model (in which the
receiver has to do something to retrieve the data later from some sort of
server) requires access to such a server on the part of the sender; use of a
'push' model (in which data is sent in the same way as text, as part of a
single transfer) is clearly better.


Security issues raised by sending binary data through email are a separate
question, but I note that those issues will mostly still exist no matter how
the binary data is transferred. (E.g. the binary might contain a virus no
matter whether it's transferred via SMTP or FTP.) The ability of email to send
to anyone does raise issues in this context, but this margin is not big enough
to fully explore them.

I also do get a little uncomfortable when email is used instead of a file
transfer system, for very large files, etc, etc. The thing is that the email
system was not designed to transfer really huge objects (although the size
allowed has been going up over time). The store-and-forward model of the
email system is not really ideal for huge objects, etc, etc.


But having said all that, the extension of the email model to send content
other than pure text - images, etc - still seems like a good idea to me.

	Noel


^ permalink raw reply	[flat|nested] 38+ messages in thread
* [TUHS] attachments: MIME and uuencode
@ 2017-03-11 19:07 Mary Ann Horton
  2017-03-11 23:01 ` Paul Winalski
                   ` (2 more replies)
  0 siblings, 3 replies; 38+ messages in thread
From: Mary Ann Horton @ 2017-03-11 19:07 UTC (permalink / raw)


I just heard from a historian named Piotr Klaban with an interesting 
historical sidelight.

Apparently today 3/11/17 is being publicized as the 25th anniversary of 
the email attachment, citing Nat Borenstein's MIME.  Piotr points out 
that uuencode predates MIME, and he's right.

I checked and, while I don't have any email archives from that time 
frame at Berkeley, I was able to find the 4BSD archive on minnie that 
dates the uuencode.1c man page at 6/1/80.  We didn't call them 
attachments back then, just sending binary files by email.  (Prior to 
then it was common to just include the text of the file raw in the 
email, which only worked for ASCII files.)  It was a few years later 
when cc:Mail and Microsoft Mail started calling uuencoded files embedded 
in email "attachments".

When MIME came out in 1992 I became a champion of SMTP/MIME as a 
standard - it was a big improvement.  But uuencod predated MIME by 12 years.

     Mary Ann




^ permalink raw reply	[flat|nested] 38+ messages in thread

end of thread, other threads:[~2017-03-19  2:34 UTC | newest]

Thread overview: 38+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-03-12 18:13 [TUHS] attachments: MIME and uuencode Doug McIlroy
2017-03-12 18:22 ` Larry McVoy
2017-03-12 18:26 ` Clem Cole
2017-03-13  0:34   ` Dan Cross
2017-03-13  1:28     ` Larry McVoy
2017-03-13  5:39       ` Dave Horsfall
2017-03-13 11:37   ` Steffen Nurpmeso
2017-03-13 20:21     ` Steffen Nurpmeso
2017-03-13 22:14       ` Doug McIlroy
2017-03-14 10:49         ` Steffen Nurpmeso
2017-03-12 18:33 ` Paul Winalski
2017-03-13  5:58   ` Dave Horsfall
  -- strict thread matches above, loose matches on Subject: below --
2017-03-12 20:04 Noel Chiappa
2017-03-12 21:34 ` Random832
2017-03-12 22:12   ` Noel Chiappa
2017-03-13 14:58     ` Michael Kjörling
2017-03-13 21:56       ` Dave Horsfall
2017-03-14 10:33         ` Steffen Nurpmeso
2017-03-16 18:52         ` Michael Kjörling
2017-03-12 18:57 Andy Valencia
2017-03-12 15:10 Noel Chiappa
2017-03-11 19:07 Mary Ann Horton
2017-03-11 23:01 ` Paul Winalski
2017-03-11 23:05   ` Mary Ann Horton
2017-03-12  1:14     ` Dan Cross
2017-03-12  6:28       ` jsteve
2017-03-12 23:41         ` Gregg Levine
2017-03-13  0:00           ` Larry McVoy
2017-03-13  1:59             ` Dave Horsfall
2017-03-12 23:43       ` Mary Ann Horton
2017-03-12 21:10   ` Dave Horsfall
     [not found]     ` <12de3888-3a82-4a8c-9177-50e6cb4cb931.maildroid@localhost>
2017-03-19  2:34       ` Dave Horsfall
2017-03-12 13:53 ` Tim Bradshaw
2017-03-12 17:42 ` Clem Cole
2017-03-12 23:35   ` Mary Ann Horton
2017-03-13  0:07     ` Clem Cole
2017-03-13  0:09     ` Warren Toomey
2017-03-13  0:11       ` Clem Cole

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