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 8 Issue 54

Tuesday 11 April 1989


o More on Otis 401 elevators
Dave Horsfall
o PC crashing network: blame the error message
Mark Mandel
o Election tampering and illegal surveillance
Brad Sherman
o Computer CAN attempt to defraud you
Peter van der Linden
o Infallible Computers
Dave Curry
o Re: Airliners running out of fuel in mid-flight
Alan Marcum
o Re: More on 1983 Air Canada near-disaster
Alan Marcum
o Airbus A320 article plus some comments
Greg Rose
o Re: CDC operating system has passwords in batch files
Steve Lidie
o NSA and Not Secure Agencies
Curtis Spangler
o California's anti-fax-ad bill...
Mark Mandel
o Info on RISKS (comp.risks)

More on Otis 401 elevators

Dave Horsfall <munnari!!dave@uunet.UU.NET>
Mon, 10 Apr 89 17:32:22 est
At the RISK of turning this into a comp.risks.elevators forum, I have some
further information on Eric Roskos' contribution:

| The elevators are "Otis Elevonic 401" elevators.  They appear to be
| microprocessor controlled; they have voice synthesizers that announce
| the floors, and scrolling text displays that give advertisements about
| the stores downstairs, the date and time of day, etc. 

[ Troubles deleted ]

Yup - those are the ones in our building too.  While I haven't noticed those
specific troubles, there are others.  They tend to cancel all calls when more
than three are selected, but there is one idiosyncrasy that I find disturbing.

I have a little hand-held (amateur) transceiver, generating just 3 watts on 147
MHz from a "rubber duck" antenna - very inefficient.  When I'm in the mood, I
trigger it next to various bits of electronic equipment, just to test their RF
susceptibility.  Imagine my surprise when the lift doors immediately flew open
(when closing), and a sepulchral voice announces "Do not be alarmed.  We are
experiencing a temporary malfunction."

Obviously, immunity to relatively weak RF fields was not a design issue.

I also get worried when their fancy flourescent display goes bizarre.  I would
hope that it is being driven by a slave computer, not the main control
processor...  I can always avoid the lifts, but 11 floors is a long way to
climb the stairs.

Dave Horsfall (VK2KFU),  Alcatel STC Australia,,  ...munnari!!dave

PC crashing network: blame the error message

Tue, 11 Apr 89 11:31 EDT
In RISKS 8:53, Patrick Wolfe describes the consequences of his
misunderstanding an error message on his PC.  The message, "use NET
START RDR hostname", was intended to mean

  "Issue the command 'NET START RDR hostname', substituting the name
   of your PC for 'hostname'."

But he interpreted "hostname" to mean the name of the host to which
the PC was connected, i.e., the network server, and the effect was to
bring down a multiuser BSD UNIX host.  He concludes:

 > The risks should be obvious.  System Managers should not be allowed
 > to touch PCs without re-reading the manuals first.  :-}

I draw a different and more enforceable conclusion:  

   THE USER TO DO SOMETHING  (or can be interpreted to do so).

Documentation is probably still the least-regarded aspect of software
production and maintenance, but it's the user's key to the product.

                                        -- Mark Mandel

Election tampering and illegal surveillance

Tue, 11 Apr 89 12:52:23 PDT
From "Eavesdropping Left and Right" in _The Nation_ of April 17, 1989, by
Gregory Flannery, reporter for the _Mt. Washington Press_, Cincinnati, Ohio.

    '... In 1979, [Cincinnati Bell's security coordinator James] West
    allegedly ordered a wiretap on lines serving vote-counting computers
    at the Hamilton County Board of Elections.  As ballots were being
    tabulated on election night, the computer shut down for two hours.
    "About 8:30 ...  election evening, Mr. West called me," [Cincinnati
    Bell installer and supervisor Leonard] Gates says. "He said we had
    done something to screw up the voting processor down there. He said,
    'You must have done something wrong.'"  Gates has testified that
    West told him the computer wiretap could be used to alter votes, but
    no evidence of such tampering has been produced to date ...'

The article also discusses other allegations which are part of a $112 million
dollar class-action suit accusing Cincinnati Bell of selling information
gathered through illegal wiretaps on client telephone lines.

        -Brad Sherman (bks@ALFA.Berkeley.Edu)

Computer CAN attempt to defraud you

Peter van der Linden <linden@Sun.COM>
Tue, 11 Apr 89 09:29:27 PDT
Apropos the recent claim that, though a computer may be wrong, it is
not trying to defraud you -- I know of a system where the computer was
programmed to defraud consumers.

A large pie manufacturing company introduced microprocessor-controlled
production lines at the end of the 1970's.  The system dispensed the
appropriate weight of filling into each pie.  State law allowed for
human inaccuracy in pie fillings - if the pie was a "4oz" pie, the
bakers were permitted to range from 3.5 to 4.5oz.  The bakers were
thrilled with the supreme accuracy of the new system, and set it to
dispense at the lower limit instead of the nominal weight, all the time.

As far as I know this dishonesty continued unchecked, and it is permitted
because the computer system allows an accuracy hitherto unobtainable.

Infallible Computers

Mon, 10 Apr 89 14:06:24 -0700
On the subject of people taking the computer's word as infallible...  did
anyone else catch "Perry Mason: The Case of the Musical Murder" on NBC Sunday

Late in the show, after our hero Mr. Mason has figured out that his client is
innocent and the witness currently on the stand is the murderer, he begins to
question the witness as to his whereabouts.  The questioning goes something

    Q: Where were you on the night of the murder at 2:30am?
    A: In my room doing script revisions.

    Q: How long were you workong on the script revisions?
    A: All night.

    Q: You use a word processor to work on the script, right?
    A: Yes.

    Q: Does the word processor put the date and time on the
       files you modify?
    A: I don't know.

    [Mason pulls out a directory listing from the fellow's

    Q: Now, next to the file "Polly", what time is shown?
    A: 1:35am

    Q: So you weren't working on the script during the time
       of the murder, you finished working on it much earlier?
    A: Yes.

And of course, the witness breaks down on the stand and confesses.

Now, granted, one can argue that it's "only television" or "just meant
as entertainment".  But judging by the idiotic things I've heard
argued based on "I saw it on [fictional show of your choice]", I
suspect a lot of people take this stuff as gospel...

Anyway, the show demonstrates the fallacy of assuming that since the
information came from a computer, it is somehow ennobled, and nobody dares to
question it.  It apparently never occurred to these people that the time of day
clock on the computer could have been wrong for some reason.

For example, the Compaq we have here for an Ethernet analyzer comes up with
some random date and time every time we turn it on.  It does not even prompt
for the correct time (since we don't really care), one has to remember
explicitly to set it (and we never bother).  In fact, on most MS-DOS systems
I'm aware of, just pressing RETURN gets you through the time/date stuff without
ever having to set it correctly.

And as another example, Sun "generic" kernels come using the Pacific Standard
time zone... how many people don't bother to change it, or just stuff the
current time in without changing the time zone?

And as still a third example... how many systems out there use the "old" rules
for daylight savings time conversions?  They would have the wrong time for a
week or so unless someone fixed it manually...

If I were the guy on the stand, I would have denied it all and forced Mason to
prove that the time of day clock on the computer was correct at the time I last
edited that file.

--Dave Curry

Re: Airliners running out of fuel in mid-flight (RISKS-8.48)

Tue, 11 Apr 89 14:30:33 PDT
Jerry Saltzer wrote that no old-time pilot would consider taking off without
personally verifying the fuel load in the plane, either by looking at it,
touching it, or dipping something in it.  As a not-so-old-time pilot (though
expecting one day to be one), I can say that most of us general aviation
pilots (and all of us GA pilots with whom I'll personally fly) STILL verify
the fuel load.

Fuel gauges, especially in general aviation aircraft, are NOTORIOUSLY
inaccurate.  I will not fly a GA plane without having eye-balled or thumbed or
dipped the fuel tanks, regardless of rain, high-wing plane with no ladder,
or whatever.

Indeed, many airliners fly without this precaution.

"An extraordinary pilot uses his or her extraordinary judgement to avoid
having to use his or her extraordinary skills."
                                                        - Alan

Re: More on 1983 Air Canada near-disaster

Tue, 11 Apr 89 14:34:00 PDT
Henry Spencer wrote that aviations regulations state that the "ultimate
authority and responsibility rest with the pilot, nobody else."  Whereas this
is certainly true in general aviation, this is NOT true in air carrier
operations.  In air carrier operations, there is a division of labor, where
many people other than the pilot in command are responsible for, and have
authority as to, various aspects of a flight.

Now, once airborn, it's the pilot's word that goes.  Period.  However, while on
the ground, during loading and dispatch and such, various ground crew members
have authority and responsibility.  Of course, it's not THEIR necks on the line
in the sky....
                                        - Alan

Airbus A320 article plus some comments (Leveson, RISKS-8.49)

Greg Rose <>
11 Apr 89 11:00:46 +1000 (Tue)
>"If a pilot has to make violent changes to the aircraft's attitude
>in an emergency, then the computer will prevent the pilot pushing it
>past design strengths. For example, the computer would prevent the pilot
>putting it into a dive that might break off the tail."

In a past issue of the "Aviation Safety Digest", published (then) by the Bureau
of Air Safety Investigation, part of the Australian Department of Name Changes
(the Civil Aviation Authority this month) was the following incident report.
[From memory]

A single engine light aircraft was flying in heavy cloud and moderate
turbulence when it apparently entered a thunderstorm cell. A severe downdraught
caused an abrupt descent, followed by wind shear causing a stall, and further
descent. The pilot broke free from the base of the cloud, still descending, and
saw lots of trees. He pulled back VERY HARD on the controls, recovered control
of the aircraft, but felt it was performing strangely, so he landed at the
first opportunity.

Subsequent examination of the aircraft showed:

a) eucalyptus leaves in the undercarriage, presumably from tree skimming.

b) the wings had undergone permanent deformation, with the tips being
   now some 30cm higher than normal. The main spar had bent in two
   places. This was attributed to 'G' forces in excess of the flight
   envelope of the aircraft.

Now my point: had this been a fly-by-wire aircraft, it would presumably never
have been overstressed. The fact that it (and the pilot) would be in little
pieces in a rainforest is, however, depressing. The pilot reacted correctly, in
that he was "between a rock and a hard place", and chose between certain death
due to trees, versus probable death due to airframe failure in flight. He was
VERY lucky to come out of this at all, but how would a computer judge between
these extremes? (Note that even if the aircraft had had a radar altimeter it
would have been hard pressed to tell the height of the treetops. If the flight
computer had tried to pull out more gracefully it might still have been an
unhappy ending.)

The simple answer is "If it had fly-by-wire, it would have had weather radar,
and this would never have happened". True, but to me, irrelevant.

The manufacturers of aircraft build in a healthy safety margin, which in this
case saved a life. But there are at least three choices with a FBW system:

1. Allow the computer to fly to the "real" (no safety margin)
   limit, on the grounds that you can trust it more than a human.  
2. restrict it to the same performance limitations as you would certify if
   there was no FBW.  
3. Forget these safety margins entirely, independent of FBW installations.

I don't like any of the above options. (2) would have killed the pilot above,
(1) and (3) are quite similar in end effect, and could see us with a rash of
airframe failures due to manufacturing tolerances, corrosion, or miscalculation
on the part of the engineers (or their software).

As has been pointed out elsewhere, extreme circumstances do happen,
and can sometimes be rectified by humans.

Aside: Harry Harrison, in "Deathworld" written in the mid-sixties, has the hero
escape captivity in a spaceship's lifeboat only to crash because the
controlling computer won't pull out of a dive quickly enough.

Re: CDC operating system has passwords in batch files (Stafleu, 8-52)

Tue, 11 Apr 89 11:19 EST
I think it is only fair to mention that using SUBMIT_JOB is just one way of
submitting a batch job, and, indeed, NOT the way that our User Services group
teaches our users.  It took me an hour to find the text that was quoted above,
in an older version of a printed manual dated April 1988.  In the current
version of NOS/VE the JOB/JOBEND construct is what the casual user first sees
when reading about batch jobs - this method of submitting batch jobs inherits
validation information from the parent job and thus there are no plain text
passwords.  The primary purpose of SUBMIT_JOB is to run jobs on OTHER

Steve Lidie, Lehigh University Computing Center

NSA and Not Secure Agencies

Curtis Spangler <>
Tue, 11 Apr 89 08:12:04 PDT
San Francisco Chronicle, Chronicle Wire Services, April 11, 1989:

               "Computer Group Wary of Security Agency

    A public interest group said yesterday that the National Security
Agency, the nation's biggest intelligence agency, could exert excessive
control over a program to strengthen the security of computer systems
throughout the federal government.

    The group, Computer Professionals for Social Responsibility - based in
Palo Alto - urged key members of Congress to focus "particularly close
scrutiny" on the agency's role in helping to implement legislation aimed at
safeguarding sensitive but unclassified information in federal computers.

    "There is a constant risk that the federal agencies, under the guise of
enhancing computer security, may find their programs - to the extent that they
rely upon computer systems - increasingly under the supervision of the largest
and most secretive intelligence organization in the country," it said."

California's anti-fax-ad bill...

Mon, 10 Apr 89 14:05 EDT
In RISKS 8:52, David M.  Gursky wonders about the legality (constitutionality,
enforceability) of California's new law against (unsolicited) junk fax, and
ends with

  > Of course, this whole message begs the question "How is this a risk
  > to society?"

Junk fax is just as much a menace as junk phone calls that seize the line and
won't let go.  While junk mail just fills up your mailbox, it doesn't deprive
you of legitimate mail unless it piles up to the very top.  Junk fax, as long
as it's coming in, ties up your machine and makes it impossible for legitimate
transmissions to reach you.
                                        -- Mark Mandel

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