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 10 Issue 39

Tuesday 18 September 1990


o Poetic Justice in a Machine Crash
Andy Glew via Paul Eggert
o Re: Expert system in the loop
Clifford Johnson
Peter G. Rose
Jeff Johnson
o I'm 99% Sure You're A Crook!!!
o A Nightmare: Security compromise with SUN's C2 package
Caveh Jalali
o Another risk of phone systems
o Desktop Publishing Fraud
Sanford Sherizen
o Data cowboys and database abuse - applicant screening
Rodney Hoffman
o Inside risks of INSIDE RISKS
o Info on RISKS (comp.risks)

Poetic Justice in a Machine Crash

Paul Eggert <>
Fri, 14 Sep 90 12:39:44 PDT
[Reprinted from comp.parallel Usenet newsgroup (Dennis Stevenson, moderator)]
From: (Andy Glew)
Newsgroups: comp.parallel
Subject: Poetic Justice in a Machine Crash
Date: 14 Sep 90 12:56:47 GMT
Organization: Center for Reliable and High-Performance Computing University of
    Illinois at Urbana Champaign

Our Encore Multimax just crashed in a way that seems like poetic justice:

    On the console terminal appeared a fragment of somebody's paper about
multiprocessor interconnection networks.  The last readable sentence was:

    " is difficult to build shared memory procesors
    "^%%^$#$%#%$#it is difficult to build shared memory$%#%$#it is difficult to
    "build shared memory$%#%$#it is difficult to build shared memory$%#%$#it is
    "difficult to build shared memory%^$%^$%^$@#$@!$@#$@difficult to build
    "shared memory$%#$%$%#$%shared memory%^$%^$%^ shared memory %&$%^^%$$%^%^$
    "shared memory&*^&*&*^&*^shared memory


Almost too good to be true :-)

(The screen garbage and control characters are not recorded verbatim).

    [Once again I am reminded of the prophetic nature of Vic Vyssotsky's
    Chaostron piece, reprinted in CACM, April 1984, pp. 356-7.  PGN]

Re: Expert system in the loop (Philipson, RISKS-10.38)

"Clifford Johnson" <A.CJJ@Forsythe.Stanford.EDU>
Fri, 14 Sep 90 14:33:30 PDT
>The commander is unlikely to ignore the advice of the expert system,
>unless it is clearly perverse.  This means that the decision (say,
>to launch a weapon) is being taken, in practice, by the expert system.

This remark incited two responses asserting that the retaliatory
decision in the case of the Vincennes was a matter of human, not
mechanical, judgment, and that the computer system merely provided
humans with better information than they would otherwise have, so
that the human decision becomes more meaningful.  This is ridiculous.

In the case of the Vincennes, it cannot be disputed that a mistake
was made.  The Pentagon found no human responsible for it, so it
must have been a mechanical error.  (Recently, Captain Rogers was
awarded a special medal of honor for his courage in commanding the
Vincennes through the shootdown.)  The assertion that humans have
time to meaningfully evaluate the computers' information in a few
minutes is patent nonsense (as proven by the Vincennes) - all
humans can do is to *gamble* whether the computers (or their readings
of the computers' consoles) are right, and so they act as no more nor
less than randomizing agencies - i.e. one would get the same level
of "judgment" by card shuffling.

Such decisionmaking is de facto *governed* by computer: without
computer prompts, no retaliatory decision at all would be taken;
and, simply because of computer prompts, a virtually immediate
retaliatory decision is mandated; and, that decision is based fully
on the information provided by the computers.

In view of these circumscribing facts, the construction that in
practice computers "make" the controlling decisions is required
both as a matter of common sense and as a matter of law, under the
realistic interpretive standards unhesitatingly applied by the
Supreme Court in Bowsher v. Synar, (1986) 106 S.Ct. 3181-3191,
which ruled that the facial freedom of a proposed officer's
decisionmaking was nullified by the circumscribing constraints:

    To permit the execution of the laws to be vested in an
    officer only answerable to Congress would, in practical
    terms, reserve in Congress control of the execution of the
    laws... There is no merit to the contention that the
    [officer] performs his duties independently and is not
    subservient to Congress.  Although nominated by the
    President... the [officer] is removable only at the
    initiative of Congress... the political realities do not
    reveal that the [officer] is free from Congress'
    influence...  [a]lthough he is to have 'due regard' for
    [executive rulings]...  The congressional removal power
    created a 'here-and-now subservience' of the [officer] to
    Congress...  In constitutional terms, the removal powers...
    dictate that he will be subservient to Congress . . .
    Unless we make the naive assumption that the economic
    destiny of the Nation could be safely entrusted to a
    mindless bank of computers, the powers that this Act vests
    in the [officer] must be recognized as having transcendent

Just so, minimal retaliatory timelines "in practical terms" assure the
dominance of military computers in Vincennes-style decisions, which gives rise
to a "here-and-now subservience" of military to to mechanical bodies.

Re: Expert system in the loop (Philipson, RISKS-10.38)

"Peter G. Rose" <CO114@URIACC.BITNET>
Fri, 14 Sep 90 14:26:51 EDT
>From: (Steven Philipson)
>In Risks 10.37, Martyn Thomas <> writes .....
<>The commander is unlikely to ignore the advice of the expert system,
<>unless it is clearly perverse.  This means that the decision (say,
<>to launch a weapon) is being taken, in practice, by the expert system.
>   Neither conclusion follows.  First, the proposed system is intended
>to "advise commanders".  It is NOT stated that the system is intended
>to act on its own or to be blindly followed.  Commanders will be very
>likely to ignore the advise of such a system — they tend to be very

There is truth in both these viewpoints.  My observations indicate that people
tend to place more faith in the 'judgment' of machines than is warrented.
Steven believes that commanders are suspicious enough of expert systems that
this tendancy is overridden.  The real issue is getting good information to the
person making the decisions, (Can you tell I'm M.I.S.?) and making sure that
the decision maker understands the system(s) that is(are) giving him
information well enough to evaluate that information.
  Most of the problems I've seen with automated systems aren't
intrinsic to the form.  They're implementation errors.
 * When you put in your 'Expert System', do you train the user to evaluate its
output, or do you train them to follow its directions?  If the people who MAKE
the system are the ones doing the training, I'd bet on the latter.
 * Does the system tell you WHY it thinks you should do something, or does it
just tell you to DO it?.  Deciding what a person does and does not need to know
is always a tricky task.
 * Is it obvious or explained HOW the system works?  It's much easier to
predict bizzare, erroneous, or just less-than-optimal performance if you've got
a good idea of how the system works.
 * When you put the system in, are you removing other sources of information?
Putting a tv camera on a vehical will let you see into blind spots, zoom, and
edit in other information. That DOESN'T mean you ought to plate-over the

The problems we have using technological artifacts are the same as we have
making the parts work in the artifact.  The pieces have to work with the
system, And the system always includes all the parts AROUND whatever you're

Re: Expert system in the loop (Philipson, RISKS-10.38)

Jeff Johnson <>
Fri, 14 Sep 90 10:35:57 PDT
>   We all wish to minimize risk, but we must recognize that we can
> not eliminate it; there are significant risks in human activities
> regardless of how they are undertaken.  There will be grave errors
> in military operations regardless of the technology that we use.

The captain of the Vincennes was faced with a decision that had four
possible outcomes:

  1. Destroy approaching plane; plane is hostile (CORRECT OUTCOME)
  2. Destroy approaching plane; plane is not hostile (ERRONEOUS OUTCOME)
  3. Don't destroy approaching plane; plane is hostile (ERRONEOUS OUTCOME)
  4. Don't destroy approaching plane; plane is not hostile (CORRECT

Mr. Philipson's statements read as if erroneous-outcomes such as case
#2 are unavoidable given the nature of decision-support systems and
human decision-making, and are qualitatively similar to errors such as
case #3.  They are neither.  Military personnel have, by joining or
accepting induction into armed service, accepted certain risks.
Civilians have not.  If there is any doubt whatsoever that the
approaching plane was hostile, the Captain should have decided not to
destroy it, accepting the risk of outcome #3, i.e., that his ship might
come under attack (Note:  not even necessarily that his ship or crew
would sustain any injuries).  He and his crew signed up for that risk
when they went to sea.  The passengers of the airliner had accepted no
such risk.  The Captain should have waited.

Jeff Johnson, HP Labs, Palo Alto

I'm 99% Sure You're A Crook!!!

Fri, 14 Sep 90 13:59:54 PDT
The following items appeared in the 9/14/90 edition of Action Line,
a consumer advocacy department of the San Jose-Mercury-News.

I recently shopped at PW Market at Landess and Morrill roads.  When I gave the
clerk my check, she immediately accused me of writing a bad check — several,
in fact.  I was totally embarrassed.  I've never bounced a check in my life!
                  — L.T.L., San Jose

[Response by Action Line.]

There was a communication problem, says Mike McMaster, store manager, who says
he's sorry you were embarrassed.  He will be sending you a letter saying so.
However, McMaster says you weren't accused of writing a bad check but
misunderstood the chain's check-clearing system, which is different from most
other stores'.  PW's system records bad checks by listing the last six digits
of the checking account number; the _complete_ checking account number is
listed in a separate booklet.  The last six digits of your account number
matched one in the store's computer, which is what caught the clerk's
attention.  After the clerk checked the book, however, she realized the rest of
your account number did not match.  McMaster says you didn't want to listen
when employees tried to explain it to you.  McMaster says PW is trying to
rework its computer system so it will accept 10-digit numbers to avoid a
similar situation in the future.

[To me, it seems like there is quite a range of quality in the machines used to
verify my credit.  Some are solid-looking hardware from NCR or IBM with
expensive keyswitches and plasma displays.  Others are cheapo stuff with LED
displays and calculator-style keypads.  I guess PW went with the system from Ma
& Pa Kettle POS Systems.  mmm]

A Nightmare: Security compromise with SUN's C2 package

Caveh Jalali <>
Mon, 17 Sep 90 15:21:35 -0700
Let's pretend to be a smart password cracker who has heard of "doing things in
parallel" and design a system that would allow us to crack passwords on many
machines simultaneously.  One might conceive of a RPC service that accepts
incoming requests for (user-name, plain text password) pairs and tests the
validity of said pair against that system's password file.  One would run this
service on every workstation, and obtain parallelism by making requests to all
workstations virtually simultaneously.


Let's say we have a typical office environment of a few file servers with 30
workstations.  We are security conscious, so we enable SUN's C2 security
package.  Typically, these workstations would share the same password file
using SUN's Yellow Pages.  All we need to do now is to install the above
mentioned service on all of these workstations and we can check about 30
passwords in parallel.  Not bad, if we could just find a way to get that
service running on all workstations...

Gee... I wonder what rpc.pwdauthd does?  Bingo!  Here is EXACTLY the
desired service.  It already runs on every SUN with C2 enabled!

When C2 is enabled, the password part of the password file is hidden from
users.  Rpc.pwdauthd fills the gap by providing a service whereby a
(user-name, plain text passwd) may be verified; this service runs on every
workstation.  One makes RPC calls to the daemon to verify a password.

Unfortunately, any one from any where may do this at any time, thus leaving the
doors open for distributed password cracking.  The cracker doesn't have to
provide his own CPUs — he can just use all the CPUs that are in your domain!

To make matters worse, rpc.pwdauthd does NOT generate any audit records even
though it makes the appropriate calls.  This is a bug — the code neglects to
set the process audit-uid and audit-state, so all auditing is ignored.

In order to hide passwords from crackers, we have instead offered crackers the
IDEAL means to do what they wanted to do in the first place: Crack YOUR
passwords, using YOUR machines, possibly using ALL your workstations!!!

00c - Caveh Jalali

Another risk of phone systems

Fri, 14 Sep 90 20:52:26 EDT
Harvard has just finished installing (at some expense) a new phone system for
undergraduate use.  By various threats and persuasion, HU has set up this
system so that no sensible undergraduate would buy phone service from any other
vendor (Only HU subscribers get listed in Harvard's Centrex directory, get
Centrex service, etc.)  To handle long distance (which subscribers to HU's
local service automatically buy from HU as well) they have set up a Personal
Authorization Code (PAC) system; to make a long-distance call from any 493-
(student) phone, the caller must enter a five-digit code that is assigned at
the beginning of the year.  Students cannot change their codes except by going
to the phone people and asking for a new one, which costs money.

A conversation I have heard at *least* five times since my arrival two days

"Gee, there are 100,000 possible PAC codes, 00000-99999.  And there are
6400 undergraduates [essentially all of whom live in dorms and subscribe
to Harvard's phone service].  That makes a 1/16 chance that a randomly
chosen code is a valid PAC code."

"So, choosing about [fiddles with calculator] 10 or 11 codes at random
gives a 50% chance of hitting a valid one."

The RISK is obvious.  This is obviously a frequent thread, but if an
institution with so many intelligent people (like, in the CS department or Math
department) can be so STUPID...

PS.  My friends at MIT tell me that their system is similar.  Is every college
this asinine, or only the decent ones? ;-)

Desktop Publishing Fraud

Sanford Sherizen <>
Sat, 15 Sep 90 16:09 EST
I would like to know if anyone has any experiences with, citations,and/or
thoughts about DTP fraud. With a relatively low investment in scanning devices,
a person could easily use desktop publishing for copying checks, certificates of
deposits, currency, diplomas, grade transcripts, licenses, etc.  A few cases
have already been found and a relatively recent article in FORBES spelled out
the problem in some clear detail.

Here are some questions that come to mind about the risks. Comments welcomed.

*  Is this truly a problem today or in the near future?

*  Are there techniques to detect scanned versus original documents?

*  Are there sufficient restrictions over the types of specialized paper stock
       that is used for currency and other financial instruments?

*  What are some of the developments in desktop publishing (or other related
       technologies) that may worsen (or even possibly contain) this type of

*  What are some of the other types of documents that people have or might copy
       for illicit purposes?

*  If there is the capability to scan and/or manipulate financial instruments,
       what will happen to the national economies of nations that are
       (somewhat) dependent upon restricted opportunities to counterfeit these

Need some extra money?  Warm up that copying machine.

Sandy                              Sanford Sherizen, Natick, MA 01760 USA
PHONE (508) 655-9888, FAX 508-879-0698, MCI MAIL:   SSHERIZEN  (396-5782)

Data cowboys and database abuse - applicant screening

Rodney Hoffman &>
17 Sep 90 07:58:18 PDT (Monday)
'Business Week', September 24, 1990, carries a story by Jeffrey Rothfeder
detailing not only the all-too-common tales of mistaken identity in
personal data, but a new category of "data cowboy" selling data it is
illegal for employers to have:

    Background checks are nosier now, and harder to fix when wrong

The lead-in tells of James Russell Wiggins being fired after six weeks on a
new job when a background check turned up a drug conviction.  "It turned
out that Equifax Services Inc., the company that investigated Wiggins'
past, had goofed:  It pulled the criminal record of James RAY Wiggins.
Wiggins was the accidental victim of increasingly common practice --
combing data bases to find information on job applicants....."

"Providing employee data to companies ... is a booming business, say data
vendors.  Sales of pre-employment data are growing as much as 75% a year
for some suppliers.  The larger players — Equifax, Fidelifacts
Metropolitan New York, and Apscreen, among others — provide more than raw
data.  They mix information from various data bases and produce summaries
that describe the applicant's financial condition, criminal and driving
records, and business relationships.  Despite the occasional mix-up, the
big data companies have earned a reputation for thoroughness."

Such checks can cost as little as $100, but some employers with high
turnover find even that too much, and turn to cut-rate data sellers who
"assemble raw, unchecked data from creidit bureaus, motor-vehicle
departments, courthouses, and other sources.  Problem is, some of the
information may not be legal to use when hiring.  'These data cowboys worry
me,' says Apscreen Pres. Thomas C. Lawson, who fears that a backlash
against them could prompt restrictions on the sale of legitimate
pre-employment information...."

"Information Resource Service Co. (IRSC) in Fullerton, Calif., for example,
sells lists of arrests that ended in acquittal, discharge, and no
disposition...." It's illegal for a employers to have such information.
Other data bases, such as Employers Information Services Inc. (EIS) in
Gretna, La., track employees who have filed for workers' compensation.

"Ernest Trent, a Pennzoil Co. roustabout who has 15 years experience,
ripped his right arm on an oil rig in 1986 and collected workers'
compensation.  Since then, he has been turned down for nearly 200 jobs.
'I'm blacklisted.'" If so, it's illegal.  "Both EIS and IRSC say they can't
control how their clients use the information they buy."

Inside risks of INSIDE RISKS

"Peter G. Neumann" <>
Tue, 18 Sep 1990 8:31:52 PDT
My piece in the September CACM (in the inside back cover section called INSIDE
RISKS) has a really strange error, in which a bulleted item appears near the
top of the last column, instead of at the beginning of the conclusions section,
with the other bulleted items.  Constantly having to live with flaky
networking, I am not surprised by anything, but do not recall having an EMail
message arrive with the order of paragraphs scrambled.  (We have of course had
numerous reports of compression algorithms going astray, lost messages,
duplicate messages, etc.)  In this case, BITNET could be the culprit, because
my copy of the same message was fine.  A context editor problem might also be

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