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 6 Issue 11

Friday, 22 January 1988


o Another One-Character Error
Earl Boebert
o Safety in MIL-STD-2167A
Nancy Leveson
o Brady Report on the Crash
Randall Davis
o Data tampering, CTFC study of Major Market Index
Randy Oppenheimer
o Court drops 'logic bomb' trial
John Pettitt
o Official word on Social Security Numbers
Rob Austein
o VAX/VMS security problem
Philip Taylor via Rob Gross
o TimeWarps as an omen
Jeffrey R Kell
o New Year's
Robert Slade
o Time-chasing
Paul Fuqua
o Re: New Year's Sun clock
Martin Ewing
o Info on RISKS (comp.risks)

Another One-Character Error

Mon, 18 Jan 88 17:16 EST
The note about the Honeywell H800 that the Air Force dropped off the
loading dock brought back this memory ...

At the time of that incident, I was an EDP Officer at Hq Air Training
Command.  Our H800 shared a computer room with the Military Personnel
Center, who had just moved the personnel records of all of the officers
in the USAF onto mag tape files on a Burroughs B5000.  The biggest job
they ran was queries, which were written in a perverted first-order
predicate calculus and asked questions like "which officers have
specialty codes equal 'xxxx' and grade equal 'Captain'" and so forth.
Individual records were pulled by the obvious query "which officers have
Service Number equal 'xxxx'..."

The program loaded a batch of queries into the B5000 and then passed the
whole tape file against it, printing "hits" on line, giving a
distinctive rhythm to the job:


One Sunday I came in to play our favorite computer game (called "Beat the H800
Compiler" or "You Bet Your Project") and noticed that the B5000 next door was


so I went over and pulled rank on the airman who was running the job.
Examination of the input showed that somebody had tried to select a
specific record, but through clerical error had inserted a "not" sign
before the "equal." Had I not intervened, this would have produced a
truckload of paper containing every officer personnel record in the Air
Force, except, of course, the one they were looking for.

Safety in MIL-STD-2167A [Safety in NUMBERS?]

Nancy Leveson <>
Fri, 22 Jan 88 07:36:17 -0800
This may be a case of me being the last to know, but from a briefing 
on the new version of the DoD standard for software development 
(MIL-STD-2167 -- now called 2167A), I learned that one of the stated 
goals of the new version is to add safety requirements.  To this end, a 
requirement has been added for the contractor "to conduct safety analysis 
to (a) minimize potential for hazardous conditions during the operational 
mission and (b) clearly identify and document hazards."  There is also a
provision added to the Software Requirements Specification DID to 
document safety requirements.

Whatever one may think of such standards in general or of these particular 
safety requirements,  including safety requirements in the software 
development standards is a step forward in awareness and concern.  

I have written a lot in various places about what I think should be done 
during software development in order to increase safety.  It would be 
interesting to me to read more in this bulletin board about specific 
approaches that others might advocate.  Given that you were in charge 
of a project to develop software to control a potentially dangerous system 
(e.g., a nuclear power plant, a medical device such as a linac, or an 
aircraft), what (if anything) special would you do to ensure acceptable 
safety?  Or if you have already had such experiences, what have you done 
and did you think it was effective and adequate?

Nancy Leveson, University of California, Irvine

Brady Report on the Crash

Sun 17 Jan 88 15:53-EST
In view of the numerous discussions about the possible role of portfolio
insurance strategies and technology in the market crash, consider these
comments from/about the recently released Brady report.  The conclusion is
that those strategies and technology were largely not causes of the crash;
there is as well a call for more use of information systems as an effective
way of monitoring the markets and preventing problems in the future.

(From a Boston Globe news analysis column 13 January 1988)

                   Brady Panel Hits Mark on the Crash
                              David Warsh

The Brady Report is just back from the printers... its recommendations boil
down to two basic strategies -- coordinate margin requiresments and establish
circuit-breakers (coordinated trading halts and existing price limits)....

For a survey done in 60 days, it's clear the panel ... has done an unusually
good job in construing what happened. ... The analytic framework seems likely
to withstand all subsequent attempts to alter it.

The story that emerges confirms what has been previously reported.  It wasn't
``Black Monday'' that was so bad, it was ``Terrible Tuesday,'' when the
markets nearly closed that was the real shocker.

And although they contributed a very substantial overhang of selling pressure
that hit the market like a tidal wave on Monday morning, new-fangled trading
strategies like portfolio insurance or index arbitrage did not ``cause'' the

If anything, various failures of the specialist system, in which 50
little-known firms commit themselves to buy and sell particular stocks in
order to keep the market orderly, provided the biggest disappointments...

In the end, the problem was in the market-mechanisms themselves, the record-
keeping and emergency protocols which permitted a ``disentangling'' of the
futures markets in Chicago and the share markets in NY.

The recommendation that Brady later described as the ``strongest'' was the one
that had the least to do with public regulation.  It was that a unified
clearing system be developed, linking the Chiago and NY markets, so that
authorities and firms can constantly monitor the shifting action when
turbulence strikes again.

With better informatin systems, portfolio insurance and other hedging
strategies would no longer pose an especially serious threat, the task force
said. ...

What we ought to be focusing on, said Brady, was ``technology, a market that's
strung together by 300,000 television screens, where a trade in NY shows up on
a screen in Tokyo 41 seconds later.  We've got one market.  We ought to be
focusing on the problems associated with that.''

Data tampering, CTFC study of Major Market Index

January 20, 1988
The Wall Street Journal (1-7-88) carried a story examining whether the Major
Market Index (MMI) was manipulated at a critical point during the stock market
crash.  The MMI is a little known futures contract index.  According to the
Journal, its "mysterious surge...may have saved the stock market from total

The gist of the story is that a study by the Commodity Futures Trading
Commission (CFTC) determined there was no evidence of any manipulation.  That
finding, the Journal reported, immediately came under attack by various
persons, who questioned even the data that the CFTC examined, claiming it may
have been doctored.  The Journal notes a congressional committee is now
investigating allegations that the data used in the study may have been
incorrect or tampered with before it was submitted to the CFTC.

The Journal article concludes: "In Chicago, a spokesman for the Board of Trade,
which supplied much of the data used by the CFTC, declined comment. A Board of
Trade official familiar with the data said he is skeptical the data could have
been tampered with, noting that it is computer-generated."

Court drops 'logic bomb' trial

John Pettitt <>
Mon Jan 18 12:40:52 1988
Reproduced without permission from 'datalink' Monday 11 Jan 1988

James  McMahon,  the  contract  systems  programmer   accused  of
planting "logic bombs" in his client's computer systems, has been
cleared of all charges.

McMahon walked free from Isleworth Crown Court, London, late last
month after the presiding judge Derek Holden accepted a mid-trial
defence   motion   that   the  evidence   against   McMahon   was
inconsistent, incomplete and lacking in reliability.

The ruling which focused on print-out and disk exhibits, promises
to be a watershed in the history of computer law, influenceing
the validity of such admissions if future cases.

The trial was billed as the UK's first "logic bomb" case, with
McMahon accused of planting unauthorised code in the DEC PDP 11
system software of air freight forwarder Pandair Freight. The
prosecution claimed that one such "logic bomb" locked terminals
at Pandair's Heston office, near Heathrow, and a second was set
to wipe the memory of the companys Birmingham computer.

John Pettitt, Specialix, Giggs Hill Rd, Thames Ditton, Surrey, England, KT7 0TR
Tel: +44-1-398-9422         Fax: +44-1-398-7122          Telex: 918110 SPECIX G

Official word on Social Security Numbers

Rob Austein <SRA@XX.LCS.MIT.EDU>
Tue 19 Jan 88 17:24:24-EST
For what it's worth, here's the "official" story on SSNs, from a
USENET posting by David Hawkins.  I have not verified the quote.

According to Social Security Administration Publication No. 05-10001 (Sept 86)

    "Any Federal, State or local agency that asks for your Social Security
     number must tell you whether giving it is mandatory or voluntary,
     under what authority the number is being requested, and what uses will
     be made of it.

     Some non-governmental organizations also use Social Security numbers
     for recordkeeping purposes.  Such use is neither required nor
     prohibited by Federal law.  Although you are not required to give
     you number, the organization is not required to provide you service
     if you do not.  Knowing your number does not allow these organizations
     to get information from your Social Security record."

I don't know how this applies to semi-public entities like utility

Use of an SSN as a Driver's License ID number poses an interesting
problem: the state government is presumably within the law in using
your SSN as their internal ID number, but should they be printing it
on your license?  Seems kinda irresponsible.  What if somebody steals
this funny little piece of plastic that the goverment requires you to
carry when you drive your car?  In effect, the state government has
just disclosed your SSN to your mugger.  Sure, the mugger's the one
who's breaking the law, but it's the state government's fault that
you're carrying your SSN around with you when you're in the car.
Maybe that's why hitchhiking is illegal in so many states? [:-)]

Of course, in states where Driver's License ID number is different
from SSN, you simply have two ID numbers that are demanded of you at
different times; they're both required for "normal life".  Not much of
an improvement.

VAX/VMS security problem

Thu, 21 Jan 88 16:54 EST
The following was recently posted to the INFO-VAX mailing list:

Date:         Tue, 19 Jan 88 12:08:50 GMT
Reply-To:     "RHBNC,
              Univ of London Philip Taylor"
Sender:       INFO-VAX Discussion <INFO-VAX@MARIST>
Subject:      VMS security

I believe I have discovered a serious loophole in VMS security. If breakin-
detection is in force, and a user enters his/her username incorrectly, without
noticing the error, then enters the correct password, that password can appear
on the operator console and in the operators' log.  This occurs when the same,
incorrect, username is entered sufficient times for breakin-detection to become
activated.  As it is not unknown for system managers to reduce the detection
limit to two, the appearance of such passwords, in clear, is a distinct

For example, a user changes his/her password; later, on logging-in, mis-types
the username (but doesn't notice the fact), and enters the old password; sees
"Invalid username/password", and remembers that he/she has a new password;
uses <Control-B>/<Up-arrow> to recall the username (to save re-typing it),
then enters the new, correct, password.  Breakin-detection is set at two, and
the correct password, plus the username with perhaps a single error in it,
appear in clear.  An unlikely scenario ?  Well, it happened to me, yesterday !

Since for common privileged usernames such as SYSTEM, it would typically be the
work of a moment to guess the mis-typed username, system security can be
seriously compromised.  Furthermore, anything which results in a valid password
being stored and displayed in clear is a serious breach of the zeroth rule of
system security.  ** Phil.

TimeWarps as an omen

Tue, 19 Jan 88 14:30:21 EDT
After reading through yet another year's assortment of clock-related bugs
an ominous realization of the scope of the Star Wars critique by David
Parnas came to light.  Every year we hear of clock-related bugs, even more
so during leap years, and may the bits beware on 1 Jan 2000.

Here we have a relatively trivial, extremely well-defined task of rolling
over a clock to update a year.  In the extremely simplistic case of mere
changes of minutes, hours, or day, there are enough "real" cases to give
a real test, and find (most) bugs.  But for more extreme cases, the testing
is done through 'simulations' and you simply are not dealing with the real
events; it is extremely difficult to test in the actual environment.  Very
few of us, I doubt, would actually bother to repeatedly reboot a real system
with the test time placed in the real clock to see if it works.

The problem is not with "inexperienced Mickey Mouse" programmers either.
Look at the IBM 3090's that called in for service due to a bug in the clock
routine during the system's early days, or the Sun problems, or any other
of the nightmares that appeared in Risks.  Many were people that "should
have known better" or "should have tested more thoroughly."

If we are unable to keep a clock/calendar operating correctly, how can we
possibly presume that a massively complex, ill-defined system like SDI can
work, combined with the impossibility of a real-life test environment?

If SDI is completed, and we must use it, and it fails, we won't have to
bother with clock-setting algorithms any longer.

Jeffrey R Kell, Dir Tech Services, Univ of Tennessee at Chattanooga 

     [It is always tempting to conclude that if such a simple thing cannot
     be done correctly, then how can 10 million lines of code work adequately?
     This is a debate that has no end, although maybe we are ready to go around
     again on SDI, a subject that has received considerable discussion in 
     earlier volumes of RISKS!  Nevertheless, the moral of the story is clear 
     -- the more complex the system, the greater the attention that must be
     paid to it, from the overall design down to the minute details...  PGN]

New Year's

Thu, 21 Jan 88 07:56:28 PST
     With regard to the computers dying over New Year's, my father in law just
came up with a real oddball. He was using Appleworks, patched to take
advantage of extra memory, a clock card, and a few other goodies. After the
Christmas holidays, his system no longer fired up automatically, and instead
had to be babied to get it to work.

     The final answer turned out to be in ProDos, a currently popular operating
system for the Apple that has superceded Apple's own DOS 3.3. A number of
clock cards for the Apple (my father in law's not being among them) do not
store the year. ProDos very kindly calculates the year from the month, day,
and day of the week. The tables for doing this, however, are limited, and
one of the anniversary dates for early versions was 1988. Later versions will
fail in future years...

Time-chasing and SSNs

Paul Fuqua <>
Thu, 21 Jan 88 22:07:09 CST
     I had some fun chasing a computer-clock problem a couple of years ago.
At that time we had six or seven Symbolics 3600 lispms, which initialise
their real-time clocks at boot time by broadcasting a request for the time on
the local Ethernet.  The machines were divided between rooms on the first and
third floors of the building.
     I noticed one day that the machine I sat down at had a wildly inaccurate
time.  Fortunately, the time-initialising code records the machine from which
it received its response;  it can be important to track down bad time
sources.  I checked the record, and trotted downstairs to discover that the
second machine was similarly inaccurate;  its response had come from a third
machine, upstairs.
     The conclusion to this story may be obvious:  I ran up and down the
stairs several times, and discovered that the last machine had received its
time response from the first!  I ended up setting the time by hand.  [It
should be noted that more recent software manages to ask only reliable
time-servers for the time.]

Paul Fuqua, Texas Instruments Computer Science Center, Dallas, Texas
CSNet: or pf@ti-csl
UUCP:   {smu, texsun, im4u, rice}!ti-csl!pf

Re: New Year's Sun clock

Martin Ewing <msesys@DEImos.Caltech.Edu>
Mon, 18 Jan 88 14:35:36 PST
On the subject of the Sun/new year's clock problem (cf Rayan Zachariasen),
which turned out to result from a mistaken use of C expression side-effects.

  >...many many people were thinking of the careless programmer
  >with warm, sizzling, thoughts.

Personally, I'd reserve a number of "warm, sizzling, thoughts" for the people
who brought us C and Unix, who made this sort of mistake almost inevitable.

    [This message is similar to other RISKS submissions that I have rejected
    in the past.  I include this one as representative of the others, but with
    a serious comment: In this field YOU ARE ALWAYS AT RISK.  If RISKS tells
    you nothing else, it is KNOW AND UNDERSTAND YOUR RISKS.  

    A comment on UNIX and C: Ken Thompson is one of the most brilliant 
    designers and programmers ever to grace this earth.  He developed UNIX
    and C primarily for his own pleasure.  It is not HIS FAULT that UNIX is
    so widely used (e.g., because of its delightful facilities for program
    development and ease of adaptation), or -- by extension -- that it is
    used unwisely in hostile environments despite its not having addressed
    critical security concerns.  A similar argument could be made by people
    who blindly accept free software from a BBOARD (e.g., the PC graphics 
    ARF-ARF Trojan horse) or a Trojan horsey virus, and then complain when
    it destroys all their files.  There are very complex tradeoffs among
    simplicity and ease of use on one hand, and safe systems (in a
    generalized sense) on the other hand.  Know your requirements before you
    start designing, programming, or simply using a computer system.  PGN]

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