The RISKS Digest
Volume 12 Issue 36

Wednesday, 18th September 1991

Forum on Risks to the Public in Computers and Related Systems

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

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AT&T Phone Failure
Ed Andrews
Fly-by-wire without leaving the ground
World Bank virus
Ted Lee
SunOS SPARC Integer Division Vulnerability
CERT Advisory
The risks of a computer-based forum
Brian Holt Hawthorne
Descriptive terms [false positives and negatives]
Jon Krueger
Risks of mistreating programmers
Arun Welch
Re: Security Software Bug Locks Up System
Sanford Sherizen
RSA stuff
John Mount
Manipulation of digital images
Joe Morris
Re: +&*#
Richard Ristow
John Wichers
Gary Beckmann
Timothy Freeman
Lynn R Grant
John F. Woods
Info on RISKS (comp.risks)

AT&T phone failure downs three New York airports for four hours

"Peter G. Neumann" <>
Wed, 18 Sep 91 9:34:13 PDT
Operations at all three New York airports ground to a standstill from 5pm until
9pm yesterday [17Sep91] when an AT&T internal power failure at a Manhattan
4-ESS switching center knocked out long distance calls in and out of the city.
Neighboring commercial power was unaffected.  The 4-ESS system is used to route
calls between AT&T's long-distance network and the local companies.  The air
traffic control centers use a network of radio towers linked by phone lines.

   Although the precise origin of Tuesday's problems remained unclear, the
   extent of the difficulties provided yet another example of how dependent
   today's telephone networks are on a few pieces of equipment.

   In recent years, AT&T and other companies have gone to great lengths to
   emphasize the back-up capacity and redundancy of their systems. Yet the
   long-distance carrier was unable to reroute all traffic to other gateways
   for several hours after the problems first became apparent.''

Calls were redirected to the two remaining gateways, but those could not handle
that much increased traffic.  [Quotes above are by Ed Andrews, whose article
``AT&T Phone Failure'' appeared in the N.Y. Times, 18Sep91.]

I just spoke with Ed Andrews, who is working on a story for tomorrow's NYTimes.
The current theory seems to be that AT&T was trying to be helpful to ConEd in
NY by cutting its usage of commercial power on a hot day by running on internal
power, but somehow did not realize that their backup power generator was not
properly linked in, and that they were actually running on batteries for 6
hours until the batteries were drained!  As the details unfold, we may find out
the extent to which the system diagnostics and alarms gave a true picture of
what was really happening.  (Shades of the Three Mile Island crew trying to
figure out what was happening?)  So, check Ed's article tomorrow for further

Here we have another example of creative redundancy and supposedly conservative
design (hardware reliability, fault tolerance, extra capacity, alternative
routing, standby power, etc.) still not being good enough to prevent massive
outages.  From the system level viewpoint, it seems that we should be learning
something more from the repeated cases of telephone outages (AT&T and Sprint
outages reported here in the past, due to software, cable cuts, etc.) and
airport shutdowns resulting from extensive telephone outages — e.g., last
year's O`Hare disruptions due to the Chicago cable cut on 15Oct90 (R.I. Cook,
RISKS-10.62, and ACM Software Engineering Notes 16 1, January 1991) and the
three New York airport disruptions due to the fiber-optic cable cut in Newark
NJ, also affecting various commodities exhanges and long-distance calling for 9
hours on 4Jan91 (RISKS-10.75 and ACM Software Engineering Notes 16 1, January
1991).  On one hand, RISKS readers know that no matter how carefully designed
and operated a system is, it can still fail grotesquely.  On the other hand, we
still have to try much harder to avoid those possibilities — and indeed
likelihoods.  You would like to think that airports and air traffic control
could find ways of not being crunched by the outage of a single switch, but
it keeps on happening!

I hope some of you will come to the ACM SIGSOFT '91 (Software for Critical
Systems) at the Fairmont Hotel in New Orleans, 4-6 December 1991, where some of
the underlying problems and potential solutions will be discussed.  In
particular, Michael Meyers of AT&T Bell Labs in Naperville will be giving an
invited talk on "Reliable Software for the 4 ESS Switch".  Henry Petroski's
talk on "Human Error in Design" is also relevant to this topic.  The
preliminary program and other information appeared in RISKS-12.10.  The
registration packet is contained in the September CACM (pp.112-113), and is
also available on-line from Judith Burgess (  I think the
program will be of great interest to the software oriented seriously minded
risks-aware community.  Peter

Fly-by-wire without leaving the ground

Tue, 17 Sep 91 22:25 EDT
James Higgins, THE DETROIT NEWS, 15 September, page 1C: ...  Clemson engineers
... have patented a new automobile camshaft/throttle control system they say
can boost fuel economy by 20 percent in a gasoline engine-- more than that in a
Diesel. ... Just by announcing the development (in a press release which, by
the way, skated lightly over some serious concerns about the new system),
Clemson has made it more likely that U.S., Japanese and German automakers will
lose their fight against tough new fuel economy legislation in Washington.  ...
A camshaft controls the action of the valves that let mixed fuel and air into
an engine and allow burned gases to escape.  Usually it's set up so that the
valves will open or close according to just one setting.  That setting is a
compromise, not...optimal...for all engine speeds. ... In the Clemson system,
the camshaft consists of two shafts, one of which rotates inside the other.  An
infinite variety of valve settings is possible, theoretically allowing optimal
valve action in every situation.

In its announcement, the university said the Clemson Camshaft system "improves
fuel economy by approximately 20 percent."  Detroit engineers object
strenuously to this, saying optimal camshaft action can only boost fuel economy
by about 5 percent.  [co-inventor] Nelson agrees.  But here's the nub--his
system also includes a computer-controlled device that electronically allows
the camshaft to act as the car's throttle--a revolutionary idea.  All cars
today have a throttle plate that opens to allow air into the engine, and in
every car on the road the throttle plate is mechanically connected to the gas

The Clemson system substitutes [for] the mechanical connection...a computer
control--a "fly by wire" device like those...on advanced aircraft.  When the
engine doesn't have to labor against a partially closed throttle, significant
fuel economy gains are possible, Nelson says.  This, together with the camshaft
action, is the source of the 20 percent figure.  But it also raises a whole
host of safety concerns--not to mention potential problems with cost,
manufacturing complexity, durability and so forth.  Overall, though, it looks
promising to this reporter.  And one hopes it will get a thorough investigation
from the industry on its own merits, free from the nasty politics surrounding
the fuel economy issue.

[and thanks to the NEWS for a commendably objective report.  -JCF]

World Bank virus

Wed, 18 Sep 91 12:16 EDT
The latest issue of Time (9/23) had the following on its "Grapevine" page.
Does anybody know any more about what it's referring to?  (I don't THINK I've
missed any issues of RISKs.)


     World Bank economists in Washington swallowed hard when the message
suddenly flashed on their screens.  Identifying itself as "Traveller 1991," an
invading computer virus announced, "Do not panic.  I am harmless."  Horrified
bank officials, who use computers to transfer billions from developed countries
to hard-pressed parts of the world, wondered at first if it was possible for
some tiny nation to fill its coffers by tapping into their inner sanctum.  An
international army of computer nerds and police experts soon tracked down the
trespasser and pronounced it harmless.  But what about the next one?  Scotland
Yard investigators, who traced the virus as far as eastern Germany, believe
that disgruntled hackers there are still at work injecting disruptive
electronic microbes into world financial networks.

CERT Advisory - SunOS SPARC Integer Division Vulnerability

CERT Advisory <>
Wed, 18 Sep 91 11:38:38 EDT
    [We generally do not include the CERT Advisories in RISKS, because there
    are so many normal channels.  But this one is absolutely fascinating as
    an example of something that ostensibly should not have an impact on
    security, so that at least the existence of the flaw should be widely
    known.  PGN]

CA-91:16                        CERT Advisory
                              September 18, 1991
                    SunOS SPARC Integer Division Vulnerability

The Computer Emergency Response Team/Coordination Center (CERT/CC) has received
information concerning a vulnerability in Sun Microsystems, Inc. (Sun) integer
division on their SPARC architecture.  This vulnerability exists on all SPARC
platforms (including sun4 and sun4c) for SunOS versions 4.1 and 4.1.1.

Sun has provided patches for this vulnerability. They are available through
your local Sun Answer Centers worldwide as well as through anonymous
ftp from the system (in the sun-dist directory).

Fix                        Patch ID       Filename            Checksum
/sys/sun{4,4c}/OBJ/crt.o   100376-01      100376-01.tar.Z     09989    11

Please note that Sun Microsystems sometimes updates patch files.  If you find
that the checksum is different please contact Sun Microsystems or us for


A security vulnerability exists in the integer division on the SPARC
architecture that can be used to gain root privileges.  Any user logged into
the system can gain root access.  [Fix info deleted.  Contact CERT.]
The CERT/CC wishes to thank Gordon Irlam of the Department of Computer,
University of Adelaide, Australia, for bringing this vulnerability to
our attention and for his further assistance with the solution.  We
also wish to thank Sun Microsystems for their prompt response to this

Computer Emergency Response Team/Coordination Center (CERT/CC)
Software Engineering Institute, Carnegie Mellon University
Pittsburgh, PA 15213-3890       Internet E-mail:
Telephone: 412-268-7090 24-hour hotline: CERT/CC 7:30a.m.-6:00p.m. EDT
Past advisories and other computer security related information are available
for anonymous ftp from the ( system.

The risks of a computer-based forum

Brian Holt Hawthorne <>
Wed, 18 Sep 91 11:57:20 EDT
Many people seem to approach e-mail and submissions to forums like RISKS as
informal conversation. Given the persistence of the typed word, however, it may
often be more appropriate to consider these forums as un-refereed journals.

Two recent examples from Volume 12, Issue 35:

Although I greatly appreciate Jeremy Grodberg's intellectual integrity spending
many hours researching the objections raised to his claims, and subsequent
posting of a retraction of those claims, I find his lack of references
disturbing. He has introduced new figures and new claims, backed up only by his
assertion of having spent "6 hours in a medical library". It is clear to me
that he may truly have found some additional sources, but it is puzzling why he
is unwilling to share them with us.

Clifford Johnson fails similarly in his diatribe against the misuse of the
MMPI. After an excellent introduction to the nature of the test and its
shortcomings, he berates "Minnesotan academics" for their "myopic" articles in
prestigious journals. Is he merely being polite by not sharing with us the name
of at least one of these journals, or a citation to at least on of these
articles of "statistical nonsense"?

While it is acceptable to make unsubstantiated statements such as these in
casual conversation, let us remember that the RISKS forum is not only archived
for posterity, but is often the subject of citations itself.

Descriptive terms

Jon Krueger <>
Tue, 17 Sep 91 20:21:45 PDT
  [There are some people who prefer TYPE ONE ERRORS and
  TYPE TWO ERRORS to False Positives and False Negatives.  PGN]

How ugly!  And a retreat from clear, forceful, prose.

Fortunately there are four perfectly good terms from signal detection theory:
hit, miss, false alarm, and correct rejection.  Here is a grid that explains
           said   \   was (what was actually the case)
      (what the    \
     test reported) \      signal              noise
       signal (yes)  |        hit      |       false alarm |
       noise  (no)   |       miss      | correct rejection |

Unlike false positives or type one errors, false alarms conveys the error and
its problems in vivid English.

Unlike false negatives or type two errors, misses denotes the type of error and
reminds us of outcomes.

This terminology gives us a reasonable way to distinguish various leading and
misleading statistics.  The chance of the test saying yes when the fact is yes
                     hits + misses

This can also be called hit rate on signal trials.

The chance of the test saying no when the fact is yes is

                      hits + misses

This can also be called miss rate on signal trials.

The chance of the fact being yes given the test said no is:

               misses + correct rejections

This can also be called miss rate on said no trials.

And the chance of the fact being no given the test said yes is:

                     false alarms
                  false alarms + hits

This can also be called false alarm rate on said no trails.

And so on.  All of these may be distinguished from the overall hit rate:

      hits + misses + correct rejections + false alarms

The overall miss rate:
      hits + misses + correct rejections + false alarms

The a priori chance of the test saying no:

               correct rejections + misses
      hits + misses + correct rejections + false alarms

The a priori chance of the fact being no:

            correct rejections + false alarms
      hits + misses + correct rejections + false alarms

Clearly these are all derived numbers.  The numbers you want are the
raw numbers in the grid, e.g.:

           said   \   was (what was actually the case)
      (what the    \
     test reported) \      signal              noise
       signal (yes)  |        50       |        10         |
       noise  (no)   |         5       |       100         |

Or more compactly, 50 hits, 10 false alarms, 5 misses, 100 correct
rejections.  From this you can derive all the numbers you want to
compare, make all the inferences the data can sustain, and make the
wisest decisions based on the available information and your personal

-- Jon Krueger

Risks of mistreating programmers

Arun Welch <>
Tue, 17 Sep 91 20:22:45 -0400
 One of our local public radio stations carries BBC news before the regular NPR
news on weekdays, and I heard this on my way home. Pardon any errors in
reporting, I was after all in a car and this is all from memory.

 Apparently there's been a rash of new computer virus infections since the
collapse of the Eastern Bloc, coming out mostly from Bulgaria.  Since the
Bulgarian government couldn't buy western computers or software, they would get
one copy illegally and then copy them freely. Since most software is
copy-protected in some manner, they trained a number of programmers to find
ways to defeat said protection. Because the programmers didn't like doing this,
and since they didn't pay them very much money, the programmers also spent some
time perfecting their skills at virus-writing. Now that it's easy to send
software back and forth, these virus' (virii?) are now spreading through the
rest of the world. The one quote I do remember is "There's one bulletin-board
system in Sophia that's absolutely notorious for them, and people are uploading
virus' to it all the time."

Arun Welch, Lisp Hacker, Anzus Consulting

Re: Security Software Bug Locks Up System (Re: RISKS-12.33)

Sanford Sherizen <>
Tue, 17 Sep 91 17:30 GMT
Dan_Swinehart ( asked me to clarify my previous posting regarding
the Tandem security software problem.  He wondered about the following:

>A faulty piece of code embedded in the Tandem Safeguard security
>system interpreted 4:22 PM on August 27 as an impossible command.

Here is all that I have available from the Computerworld article.

"A unique combinations of numbers generated by Tandem's "time stamp" facility
thretened to stop ....computers at precisely 4:22 pm in each local time
zone...'The time stamp took on a numerical value that would trigger incorrect
computer logic,' one West Coast Tandem user explained.  'The security package
would then lock up the system...' ...The culprit was a faulty piece of software
code embedded in the Tandem Safeguard security system that interpreted the data
and time numbers as an impossible command...The computers that felt the bug
were Tandem VLX and Tandem Cyclone systems running the new C 20.2 release of
the Safeguard security package along with Tandem's Guardian operating system."

Hope that clarifies the posting.   Sandy
Data Security Systems, Inc. ,5 Keane Terrace, Natick, MA

RSA stuff

John Mount <>
Wed, 18 Sep 91 09:42:54 -0400
I have some problems with Jerry Leichter's summary on RSA (which is for the
most part right on target).  For brevity I am only quoting the parts of his
article I disagree with- but I want it known that all the points I deleted I
think were stated well and agree with 100%.

>        It is widely believed that factoring is, in fact, NP-complete.
>        However, the same was believed of linear programming until
>        Khachian's algorithm.

No, factoring is in NP intersect coNP and it is widely believed that
no problem in NP intersect coNP is NP complete (but who knows).  People do
believe that factoring is hard though.  I also (vaguely) remember a theorem
that any problem you can build a public key code out of is going to be
in NP intersect coNP because you could verify both positive and negative
instances of the problem by watching a party with the key information
classify messages as legitimate or forgeries.

>                                                        If P = NP, public
>        key cryptography becomes impossible.  (However, private key
>        cryptography can still be possible.)

If P=NP then if the amount of information (entropy in Shannon's sense) in a
series of messages exceeds the amount of information in the encryption key then
you can learn something about the messages.  So if P=NP private key
cryptography is still possible- but only with *large* keys (like one time

Manipulation of digital images

Joe Morris <>
Wed, 18 Sep 91 11:07:15 -0400
The new (October 91) issue of _Publish_ has a well-written article on the
ethical issues raised by the manipulation of photographic images by computer.
It doesn't go into the legal implications of this manipulation (e.g., the
issues of evidence in a court case) or similar consequences, but it does
provide a nice summary of the situation.

The article also has a subhead that sounds as if it came from one of the
asides that PGN sticks into RISKS postings:

     "Reach Out and Retouch Someone"

Recommended reading.   Joe
                                 [Spanked with an Electronic Airbrush?  PGN]

Re: +&*#$ (Clements, RISKS-12.33)

Richard Ristow <>
Mon, 16 Sep 91 17:37:29 EDT
For what it's worth, the diacritic in question is apparently also called the
"caron", for example in ISO standard 8879-1986(E) and thence in documentation
distributed with the University of Waterloo SCRIPT markup and formatting

This caused several days of searching, E-mailing, and general handwringing on
my own part, that of the SCRIPT maintenance person at Brown University, and the
Brown University reference librarians when I innocently asked, where's the
hacek?  and what is a "caron" good for?  Discussion on list ISO8859 raised and
sort of answered the same point; apparently "caron" is a legitimate word for
the diacritic, but so obscure that Slavic language specialists have rarely
heard of it.  But it CAN be written in ASCII...

Richard Ristow     AP430001@BROWNVM.BROWN.EDU    Bitnet: AP430001@BROWNVM

Re: +&*#$ (Roberts)

JJJJJust JJJJJohn <>
Mon, 16 Sep 91 21:53:34 -0400
I would argue that Mike is simply taking a requirement (the unique id each
motor vehicle must carry) and combining it with a chance to express his
individuality. I strongly doubt that the vast majority of people who have
vanity plates would plaster the same message on the sides of their vehicles
if they were not required to have plates.

>Society allows people to advertise themselves by writing their name, slogan,
>etc as big as they like on their vehicles - many elements of society do that
>and the results can be seen driving down any road any day.

Society also allows people to advertise themselves, within certain limits,
by getting vanity plates. If it is such a detriment to society then it would
have been legislated out of existence. Since that's not the case I don't see
why Dave is upset about Mike and others who are well within the law in
expressing themselves.

>The society we live in takes money from each and every one of us to spend on
>the common good.

Mike pays taxes as well. He certainly should have the right to express
himself. I don't agree with Plato's view of the ideal society as being an
antlike colony in which individuality can't/shouldn't exist (or if it
exists, can't mainfest itself).

>PS. I think he also owes all the other John Does paying taxes for the time
>of one cop and one car and one computer system for the wasted effort caused
>by his insistence on a misuse of vehicle number plates;  the RISK is loss
>of availability of a cop who could be doing something useful instead.

The problem with this argument is that Mike was *not* misusing his license
plate. The problem, and the RISK, is that society allows people to have
non-standard plates without properly dealing with the consequences. If anyone
owes anything for the waste of the cop's time (and Mike's!), it should be the
people who designed the computer system without taking into account all of the
possible legitimate plates. Don't blame the effect for the cause.
                                                                --John Wichers

re: ##$@*, !names, umlauts and other nonstandard print chars...

Gary Beckmann <>
Tue, 17 Sep 91 15:45:28 EDT
H. Fuss comments regarding umlauts, etc. remind me that the German speaking
Swiss do not use the es-zet anymore.  Though it is unclear to me when they
stopped using it, I believe it must be before the wide spread use of computers
since an aunt (from Austria) who went to school for a while in Switerland had
the other children fascinated with her "funny" way of writing "double-s's".

The use of an 'e' for the umlaut causes a problem if you finally get
the hardware to print umlauts.  How do you update you database?  A
global search-and-replace would cause you problems if you changed the
poet Goethe's name.

Did some one say computers were supposed to make our lives easier?

                    Gary Beckmann

Re: +&*#$ (Roberts)

Tue, 17 Sep 91 12:25:36 -0400
> PS. I think he also owes all the other John Does paying taxes ...

You are misplacing the blame here.  The bureaucracy that controls the license
plates sells personalized plates for a fee.  They even advertise this (in the
US, anyway).  If this bureaucracy is stupid enough to advertise an offer that
causes them more trouble than it is worth, the blame belongs squarely on the
shoulders of the bureaucracy, not on the person who accepted the offer.

>  PPS. Whether traffic cops in patrol cars EVER do anything useful is
   not a topic for this newsgroup - we all pay them so we all think
   that they do!

The connection between opinion and governmental action is much more tenuous
than you say.  People vote for legislators, not for policies, and a majority
isn't a consensus.

Re: +&$ (Roberts, RISKS-12.34)

Tue, 17 Sep 91 12:42 EDT
Perhaps this is getting peripheral to the original discussion, but I cannot let
Dave Roberts's characterization of ham radio license plates as a misuse of
license plates go unchallenged.

Ham radio plates are not a misuse of the system--they are sanctioned by it.
For example, in two states where I have lived, Michigan and Illinois, hams pay
a very small fee (about $2) or nothing at all for the privilege of having their
call sign on their plates, while other who get personalized ("vanity") plates
pay a substantial sum (about $75, if I remember correctly).

There are a couple of reasons why the state governments do this.  Ham radio
operators provide emergency communications during tornados, floods, and other
disasters.  Frequently ham radio emergency groups will have operators stationed
in the police departments and weather service offices, relaying information
between the government networks and the ham radio emergency networks.  Being
able to identify the vehicles of radio operators during an emergency is a
useful thing.  Of course, not all hams are involved in emergency service, but
there's a good chance that those at the site of an emergency are.

Also, state governments issue the ham plates to comemorate the service
of ham radio operators, just as they have (at least in Illinois) Armed
Forces plates, and purple heart plates, and ex-POW plates, and the like.

So, if the government of California issues ham plates, but can't find
them in their computer, this is a standard computer data entry problem,
not a misuse of the system by ham radio operators.

Lynn Grant N8AF (Grant at Dockmaster.NCSC.MIL)

Re: +&*#$ (Moore, RISKS-12.27)

John F. Woods <>
Mon, 9 Sep 91 14:39:40 EDT
>... would not accept a license number of WA0DVD - ...

Possibly he was reading the zero as an O.  Someone in rec.ham-radio some time
ago mentioned that, in California, they once had some trouble during a traffic
stop because of their plate: WB6OOO (oh oh oh).  The policeman was *sure* it
was a bogus plate, because letter-letter-four-digits is the pattern used for
commercial vans (I believe), which the passenger car in front of him plainly
wasn't.  And sure enough, the computer had no record of "W-B-6-thousand".
Fortunately he eventually was convinced to try W-B-6-oh-oh-oh, and after some
gyration getting the person on the computer to type it in right, was rewarded
with valid registration info.  Oh-Oh-Oh indeed.
                                                     John Woods (WB7EEL)

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