The Risks Digest

The RISKS Digest

Forum on Risks to the Public in Computers and Related Systems

ACM Committee on Computers and Public Policy, Peter G. Neumann, moderator

Volume 11 Issue 66

Monday 13 May 1991


o "Children of the Computer" To Teach Our Children
Jay Elinsky
o Case of the Replicated Errors: An Internet Postmaster's Horror Story
Erik E. Fair
o Trojan pipe to login on 4.x bsd
Mark Seecof
o Emergency off switch - IBM 1620
Martin Ewing
o Re: Rude Behavior
Bill Murray
o Re: Where justice is done ...
Richard A. O'Keefe
o Re: Quirk in British Computer Privacy Laws
Paul Johnson
Chaz Heritage
John ffitch
o Re: Dagobert (NL) or Scrooge McDuck (UK/US)
Herman J. Woltring
o Info on RISKS (comp.risks)

"Children of the Computer" To Teach Our Children

Mon, 13 May 91 00:21:53 EDT
The Sunday, May 12 edition of the New York Daily News has the front-page
headline "The Brain Drain -- City faces flood of novice teachers".  One
of the hopeful new teachers, who will replace old-timers lured out by a
retirement incentive, is a 23-year-old student teacher in English, whose
name and alma mater I will omit even though they're given in the article.

His cooperating teacher gives him high marks for energy and creativity.
"[He] concedes, however, that spelling and grammar are not his strong
suits, and that he is working hard not to repeat spelling mistakes such
as `hatrid', `envolved', or `increduluous' when he writes on the blackboard
or in homework assignments.  `I'm a child of the computer.  I'm used to
pushing 'spellcheck' and that corrects the words'".  As I said above, he's
a student teacher in English.

Jay Elinsky, IBM T.J. Watson Research Center, Yorktown Heights, NY

   [Good speling and gramar arent everything but it shure helps.
   I include this item here to remind us that discipline can easily stifle
   creativity, but that creativity without discipline may be of very
   limited value.  It clearly helps to have some discipline, energy,
   creativity, and perhaps even some intelligence!  PGN]

Case of the Replicated Errors: An Internet Postmaster's Horror Story

"Erik E. Fair" (Your Friendly Postmaster) <fair@APPLE.COM>
Thu, 09 May 91 23:26:50 -0700
    [Forwarded to RISKS by Jerry Leichter <> and Jim Horning]

This Is The Network: The Apple Engineering Network.

The Apple Engineering Network has about 100 IP subnets, 224 AppleTalk zones,
and over 600 AppleTalk networks. It stretches from Tokyo, Japan, to Paris,
France, with half a dozen locations in the U.S., and 40 buildings in the
Silicon Valley. It is interconnected with the Internet in three places: two in
the Silicon Valley, and one in Boston. It supports almost 10,000 users every

When things go wrong with E-mail on this network, it's my problem.
My name is Fair. I carry a badge.

[insert theme from "Dragnet"]

The story you are about to read is true. The names have not been
changed so as to finger the guilty.

It was early evening, on a Monday. I was working the swing shift out of
Engineering Computer Operations under the command of Richard Herndon.  I don't
have a partner.

While I was reading my E-mail that evening, I noticed that the load
average on, our VAX-8650, had climbed way out of its normal
range to just over 72.

Upon investigation, I found that thousands of Internet hosts were trying to
send us an error message. I also found 2,000+ copies of this error message
already in our queue.

I immediately shut down the sendmail daemon which was offering SMTP service on
our VAX.

I examined the error message, and reconstructed the following sequence
of events:

We have a large community of users who use QuickMail, a popular macintosh based
E-mail system from CE Software. In order to make it possible for these users to
communicate with other users who have chosen to use other E-mail systems, ECO
supports a QuickMail to Internet E-mail gateway. We use RFC822 Internet mail
format, and RFC821 SMTP as our common intermediate E-mail standard, and we
gateway everything that we can to that standard, to promote interoperability.

The gateway that we installed for this purpose is MAIL*LINK SMTP from Starnine
Systems. This product is also known as GatorMail-Q from Cayman Systems. It does
gateway duty for all of the 3,500 QuickMail users on the Apple Engineering

Many of our users subscribe, from QuickMail, to Internet mailing lists which
are delivered to them through this gateway. One such user, Mark E. Davis, is on
the mailing list, to discuss some alternatives to ASCII with
the other members of that list.

Sometime on Monday, he replied to a message that he recieved from the mailing
list. He composed a one paragraph comment on the original message, and hit the
"send" button.

Somewhere in the process of that reply, either QuickMail or MAIL*LINK SMTP
mangled the "To:" field of the message.

The important part is that the "To:" field contained exactly one "<" character,
without a matching ">" character. This minor point caused the massive
devastation, because it interacted with a bug in sendmail.

Note that this syntax error in the "To:" field has nothing whatsoever to do
with the actual recipient list, which is handled separately, and which, in this
case, was perfectly correct.

The message made it out of the Apple Engineering Network, and over to Sun
Microsystems, where it was exploded out to all the recipients of the mailing list.

Sendmail, arguably the standard SMTP daemon and mailer for UNIX, doesn't like
"To:" fields which are constructed as described. What it does about this is the
real problem: it sends an error message back to the sender of the message, AND
delivers the original message onward to whatever specified destinations are
listed in the recipient list.

This is deadly.

The effect was that every sendmail daemon on every host which touched
the bad message sent an error message back to us about it. I have
often dreaded the possibility that one day, every host on the Internet
(all 400,000 of them) would try to send us a message, all at once.

On monday, we got a taste of what that must be like.

I don't know how many people are on the mailing list, but I've
heard from Postmasters in Sweden, Japan, Korea, Australia, Britain, France, and
all over the U.S. I speculate that the list has at least 200 recipients, and
about 25% of them are actually UUCP sites that are MX'd on the Internet.

I destroyed about 4,000 copies of the error message in our queues here
at Apple Computer.

After I turned off our SMTP daemon, our secondary MX sites got whacked.
We have a secondary MX site so that when we're down, someone else will
collect our mail in one place, and deliver it to us in an orderly
fashion, rather than have every host which has a message for us jump on
us the very second that we come back up.

Our secondary MX is the CSNET Relay ( and  They
eventually destroyed over 11,000 copies of the error message in the queues on
the two relay machines. Their postmistress was at wit's end when I spoke to
her. She wanted to know what had hit her machines.

It seems that for every one machine that had successfully contacted
and delivered a copy of that error message, there were three hosts which
couldn't get ahold of because we were overloaded from all the mail,
and so they contacted the CSNET Relay instead.

I also heard from CSNET that UUNET, a major MX site for many other hosts, had
destroyed 2,000 copies of the error message. I presume that their modems were
very busy delivering copies of the error message from outlying UUCP sites back
to us at Apple Computer.

This instantiation of this problem has abated for the moment, but I'm still
spending a lot of time answering E-mail queries from postmasters all over the

The next day, I replaced the current release of MAIL*LINK SMTP with a
beta test version of their next release. It has not shown the header
mangling bug, yet.

The final chapter of this horror story has yet to be written.

The versions of sendmail with this behavior are still out there on hundreds of
thousands of computers, waiting for another chance to bury some unlucky site in
error messages.

Are you next?

[insert theme from "The Twilight Zone"]

    just the vax, ma'am,

    Erik E. Fair    apple!fair

trojan pipe to login on 4.x bsd (Re: Graham-Cumming, RISKS-11.65)

Mark Seecof <>
Fri, 10 May 91 16:56:14 -0700
> >From: John Graham-Cumming <>
> Has anyone else had a similar problem with piping and LOGIN?

    On many Unix's with BSD features you can fool, not login, but 'su -'
(simulate a login) which might "do the job" of of fooling the user (his utmp
entry will be wrong).  To accomplish this you must use the TIOCSTI ioctl in a
clever way (I am reluctant to say more).  I think that the getpass(3) routine
could probably be modified to limit this attack by messing with the terminal's
distinguished process group (TIOCSPGRP).

Mark Seecof, Publishing Systems Department, Los Angeles Times, Times-Mirror
Square, Los Angeles, California  90053                         213-237-5000

Emergency off switch - IBM 1620

Martin Ewing <ewing-martin@CS.YALE.EDU>
Sat, 11 May 1991 03:22:15 GMT
Remember all the risks we unknowingly took in our youth?  Driving without
seatbelts, using lawnmowers without automatic shutoffs, etc.?  Well, there were
computing risks like those, too.  Recently wandering through the library
stacks, I came across "Programming the IBM 1620" by Clarence B. Germain
(Prentice-Hall, 1962). (The 1620 was a scientific machine with variable word
length and 1-5 KIPS -- don't ask about SPECmarks.)

I was going over the control panel description when I came upon the

  Finally, we should mention the EMERGENCY OFF SWITCH... It removes all
  power from the machine instantly.  Damage to the machine results
  from its use, and a customer engineer is required to turn the machine
  back on.  Unless the computer is struck by lightning while you are
  using it, do NOT touch this switch; it is for emergency use only.

Men were men in those days, and giants strode the earth.

Martin Ewing, Yale University

Rude Behavior (Where justice is done, Woltring, RISKS-11.65)

Fri, 10 May 91 22:28 EDT
Not all rude behavior should be criminal.  The Dutch have always tolerated
behavior that other people have criminalized.  Who are we to tell the Dutch
what level of rude behavior they should be prepared to tolerate?

>Thus, the ball is bounced back in the case of the attacked American

Ah, there is the rub.  The behavior of the Dutch students is not confined to
their country.  Are we prohibited from telling the Dutch what level of rude
behavior we are prepared to tolerate?

Not only are the Dutch not prepared to call that behavior criminal, they do not
appear to be inclined to label it rude.  Not only are they not prepared to
invoke criminal sanctions, so far they have refused to invoke social sanctions.
While they contend that criminal sanctions are not warranted, they continue to
fund the little rowdies.  While they seem to object to being labelled a rogue
nation, otherwise responsible citizens of that nation insist upon defending and
justifying this behavior and trying to blame the victims.  While they clearly
have the option to confine this behavior within their own borders, they do not
do so.  What are the rest of us to do?  Have we no choice but to provide the
playpen for brats?

HJW's assertions to the contrary notwithstanding, this is not an issue of the
security of American systems.  While our systems may not be more secure than
those in the Netherlands, they are no less so.  Neither are they less secure
than those in the rest of the internet.  While our systems are the targets of
these attacks, it is the systems in Europe, specifically including those in the
Netherlands, that are paying the cost of attack.  Our systems are the targets,
but we are no more the victims than the rest of the internet.

Given the number of systems in the internet, the level of security is a given;
it cannot change much in a short time.  Given the law of large numbers, given a
normal distribution of security in systems within the net, the net will always
be vulnerable to this kind of attack.

"Computers at Risk," the report cited by HJW, would have you believe that the
problem is one of the systems shipped by vendors.  If vendors did a better job
of design and chose safer defaults, the problem would be solved.  Would God
that that were so.  It would be lovely to have to deal with only thousands of
vendors instead of millions of users.

While good design and safe defaults may be necessary to security, they are not
sufficient.  Do any of you seriously believe that there is any security that a
vendor can put into a system that users cannot compromise away?  Do you believe
that if a vendor could do so, that all of us his competitors would follow his
lead?  That no vendor could be successful selling performance and function at
the expense of security, or that none of the systems that he sold on that basis
could find their way into the net?

This is not simply an issue of the security of the systems within the net.  The
security of the net is, only in part, a function of the security of the systems
in it, it is also influenced by other properties and behavior of those nodes.
If you can believe the report, the Wily Hacker used the system of the Mitre
Corporation as it was intended to be used.  However, that intention so reduced
the Wily Hacker's normal and expected cost of attack that it put the rest of
net at risk.  In taking his scientific/law-enforcement response to the attack,
Cliff Stoll put his neighbors at risk.  Now, he was at least watching to be
sure that the Wily Hacker was not too successful, but wouldn't you expect your
neighbor to pull the plug on him?

Note that the security of a given system does not protect it.  My system may be
sufficiently resistant to outsiders to keep the Dutch students out.  However,
it does not keep them from using the adjacent system to attack me.  The attack
is a problem without regard to its success.  It consumes some cycles, but it
consumes an inordinate amount of communication capacity.

So, what are we to do?  Assume that the Dutch students continue their rude
behavior.  Assume that their elders continue to fund them and smile tolerantly
on the little hoodlums.  Must we simply tolerate it?  Have we no other open
options?  How long will we tolerate this abuse before we break the connection?

Now, I was not surprised at the response when I suggested this remedy last
month.  I expected that a community dependent upon connectivity would be
reluctant to use that connectivity as a control mechanism.  I was a little
amused at the over-statement that was used to attack the idea.

I did not suggest that we ostracize Holland (Go back and read it if you must)
though I did say that we should be prepared to do so.  I did not even suggest
that we permanently bar any systems from the net.  It did not occur to me that
anyone would think that the disconnections would need to be permanent or even
of long duration.  One of these days I will learn that if you leave room to be
misconstrued, you can expect to be.

I only said that if you get rude traffic, break the connection to the system
that it is coming from.  Tell them why you have done so.  If they are not the
origin, invite them to follow your example.  (Of course you can restore the
connection as soon as the rude traffic stops.)

That is all I said to do.  If everybody does that, the rude traffic will be
isolated at its source.  Now, the originators may continue to send the rude
traffic, but I doubt it.  If no system will listen, who will they send it to?
Their elders may continue to fund "their experiments," but I doubt it.  If we
stop playing victim, the fun will go out of their playing bully.

I have to confess that I was surprised that some readers concluded that I
advocated having data police and that I was nominating myself for the job.  Let
me make it clear.  What I want is an orderly network that needs no policing.
What I want is the kind of orderly well-behaved network that we have enjoyed
for almost two decades.  To the extent that there is any requirement for
policing, what I am proposing is self-policing.  What I am resisting is the
idea that between what is illegal and what we can prevent, we must expect and
tolerate everything else.  What I am resisting is the idea that our only hope
for order is to appeal to the authority of the law.

Finally, let me conclude with a regret.  I regret that this has become a
national issue.  I particularly regret that the nation involved is the
Netherlands.  I hope they take no more offense at my rhetoric than is intended.
If all the world were as civilized as the Netherlands, it would be a better

Nonetheless I am convinced that the rhetoric is indicated and I hope that it
gets their attention.  I am concerned that these otherwise most orderly of
people appear not to understand that they are fostering mischief.  I am
concerned that they seem not to realize that they are setting in motion forces
which they cannot control and inflicting damage on public order which may not
be reversible.

William Hugh Murray, Executive Consultant, Information System Security
21 Locust Avenue, Suite 2D, New Canaan, Connecticut 06840       203 966 4769

Re: Where justice is done ... (Woltring, RISKS-11.65)

Richard A. O'Keefe <>
13 May 91 09:08:39 GMT
I'm sorry to keep this topic going, but I am rather distressed by this.
People keep writing as if "unauthorised entry" were only a threat to big
universities and Government sites, as if the only reason for a site to
be vulnerable is negligence or incompetence.  "It's easy, just put a B2
layer in between your net and the rest of the world!"  "It's *just*, you
only have to convince the court that your system was secure."

That's not my perspective.  I'm worried about small organisations (as I
said before, I have a particular charity in mind) for whom an 80386
running UNIX V.3 is a *large* expenditure, for whom buying an extra PC
would be a financial hardship.  These people could benefit a lot from
being on the net.  E-mail could save them a lot of money.  Remote access
could cut down on consultants' fees (no need to make a physical trip).
There must be many thousands of small businesses in the same situation.

*These* people are vulnerable to "unauthorised entry" too.  Why would
anyone break into a system with no juicy data sets &c?  Well, why do
people spray graffiti all over the trains?  Why do people try to burn
down schools?  Would anyone really break into a charity's computer and
destroy files if they thought they could get away with it?  YES!

Whatever "security" requirement is demanded of a victim before the
courts will protect them should not be more than the victim could
(a) reasonably be expected to know about, not being a computer expert
(b) reasonably be expected to afford, bearing in mind the cost of the
data and computer system.

Re: Quirk in British Computer Privacy Laws

paj <>
13 May 1991 10:16:03-BST
Ed Ravin <elr%trintex@uunet.UU.NET> quotes The Economist on the UK Data
Protection Act, saying that in order to evade the right to personal information
about you held on computer, reporters write anticipated obituaries on paper.

A far worse example was (possibly is) the university I attended.  In those days
it was University College Cardiff.  It did not allow students to see their
records, and held them on paper in order avoid having to do this.  Processing
was done by computer under a DPA clause which permits temporary storage for a
limited time without having to have the data registered.  Then the data was
printed out and the magnetic media erased.  The next time it was needed it was
re-keyed.  I found this to be a truly stunning way of doing things.

I also glanced through the report which preceded to the DPA.  There was mention
made of this issue.  Many of the experts who gave evidence stressed that the
distinction between computerised data and manually held data is an arbitrary
one.  The report noted that this was probably true but that the protection of
paper files was outside their brief, so they could not consider it.

Hanlon's Razor: Never attribute to malice that which can be adequately
explained by stupidity.

Paul Johnson      +44 245 73331

British Privacy Law (Ravin, RISKS-11.63)

Mon, 13 May 1991 04:28:00 PDT
> When the subject is no longer in a position to demand his right to freedom of
information, the obituary is then put into the computer for publication.

This was not the reason why manually held records were excluded from the
provisions of the Data Protection Act, 1984. British law does *not* 'let
individuals look at computerised information that others may hold about them'.
Perhaps Mr. Ravin should read the Act. His faith in British law is touching,
but is quite misplaced.

Re Quirk in British Privacy Laws

Mon, 13 May 91 15:28:07 BST
When we at the university were looking at the implications of the so-called
Data Protection Act I was led to asking the questions about the use of
scanners.  We were concerned with the procesing of examination marks, and as we
include second year results in out final examination we wondered if printing
them and deleting the files, and then scanning would be OK.  The opinion we got
was that if you intend to re-enter the information then it still comes under
the DPA.  (The court case inquiring what I intended to do could have been
interesting.  :-)  )

  However in the case of obituaries the situation is different.  The DPA does
not apply to information about dead people, as that is not personal.
  An amusing sideline to this is we considered the holding of bibliographies,
which were then searched, which would be personal data, and so we would have to
register under the law.  However if we sent the university hit squad round we
could save the serious offence of holding unauthorised personal data, if at the
expense of a murder or two.

                                             ==John ffitch

Re: Dagobert (NL) or Scrooge McDuck (UK/US) [RISKS-11.58]

"Herman J. Woltring" <>
Fri, 10 May 91 23:00 MET
When I referred to "Dagobert Duck" in my RISKS-11.58 posting, I did not realise
that this personality is called Scrooge McDuck in Anglosaxon (and, I believe)
American parlance.  I trust that the identification was unambiguous by context!

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