The RISKS Digest
Volume 9 Issue 8

Friday, 28th July 1989

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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o Returning before departing on airline reservation systems
Gary McClelland
o Sun security problem: restore
J. Paul Holbrook
o Computer condom?
Jeff Stout
o Robert Tappan Morris indicted
Steve Den Beste
o Re: UK Defence Software Standard
Mark Moraes
Douglas W. Jones
o Polling vs. interrupts
Douglas W. Jones
o Software Engineering Models (John
J.G.) Mainwaring
o Single Point of Failure for Internet Management
Kee Hinckley
o DARPA contract & AI for moving targets
Bob Estell
o Two-Word Last Names and Other Amusing Database Stories
Gary McClelland
o Credit card issuers invade cardholders' privacy
Andrew Klossner
o Re: windowless cockpits
Andrew Klossner
o Info on RISKS (comp.risks)

Returning before departing on airline reservation systems

"Gary McClelland" <>
25 Jul 89 15:23:00 MDT
From the "Rumor Roundup" column in DIGITAL REVIEW (trade newspaper that tracks
DEC doings) of 17 July 1989:

    My DEC friends tell me that DEC employees now have a special way
    of traveling back in time.  It seems that a memo on the internal
    electronic bulletin board goes on at great length about how to
    take advantage of a loophole in the rules governing domestic
    discount airfares.  By booking the return flight as the departing
    flight, and the departing flight as the return flight, the airline
    computer system thinks the traveler is staying over the weekend.
    Apparently, the reservations program does not understand that
    people have to leave before they can return.

Gary McClelland,

Sun security problem: restore

Wed, 26 Jul 89 09:20:48 EDT
A security hole has been found in SunOS restore.  This problem affects
SunOS 4.0, 4.0.1, and 4.0.3 systems.  It does not appear in SunOS 3.5.
The problem occurs because restore is setuid to root.  Without going
into details, is sufficient to say that this is a serious hole.  All
SunOS 4.0 installations should install this workaround.  Note that a
user does need to have an existing account to exploit this hole.

There are two workarounds that will fix the problem.  The first is
slightly more secure but has some side-effects.

1) Make restore non-setuid by becoming root and doing a
chmod 750 /usr/etc/restore

This makes restore non-setuid and unreadable and unexecutable by
ordinary users.

Making restore non-setuid affects the restore command using a remote
tape drive.  You will no longer be able to run a restore from another
machine as an ordinary user; instead, you'll have be root to do so.
(The reason for this is that the remote tape drive daemon on the
machine with the tape drive expects a request on a TCP privileged
port.  Under SunOS, you can't get a privileged port unless you are
root.  By making restore non-setuid, when you run restore and request
a remote tape drive, restore won't be able to get a privileged port,
so the remote tape drive daemon won't talk to it.)

2) If you do need to have some users run restore from remote tape
drives without being root, you can use the following workaround.

cd /usr/etc
chgrp operator restore
chmod 4550 restore

This allows the use of restore by some trusted group.  In this case,
we used the group 'operator', but you may substitute any other group
that you trust with access to the tape drive.  Thus, restore is still
setuid and vulnerable, but only to the people in the trusted group.

The 4550 makes restore readable and executable by the group you
specified, and unreadable by everyone else.

Sun knows about this problem (Sun Bug 1019265) and will put in a more
permanent fix in a future release of SunOS.

J. Paul Holbrook, Computer Emergency Response Team,
Internet: <cert@SEI.CMU.EDU>      (412) 268-7090 (24 hour hotline)

Computer condom?

Mon, 24 Jul 89 10:59:30 PDT
[From the Seattle Weekly, 5/3/89]


Every worry that your computer might be hanging out in a network where it
will pick up some disgusting virus?  Empirical Research Systems of Tacoma
suggests you supply it with one of their "computer condoms".  This high-tech
prophylactic is a combination of hardware and software embodied in a
controller card that simply replaces the one already in the machine.  Rick
Cummings, the company's president, says the system "stops all viruses" by
monitoring the user network, the keyboard, and the program in use.  He notes
that the system is programmable to alter the parameters of its control on
any given machine, but he guarantees that, "when programmed to your
requirements, it will not allow viruses to enter."

The technology was developed through successful efforts to protect a group of
European banks from the massive virus that penetrated European computer
networks last autumn.  "Naturally these became our first orders," Cummings
says.  He has since picked up an additional 2500 firm orders in Europe, with
5000 more contingent on inspection of the product.  In the United States, the
product has been reviewed by Boeing Computer Services and computer technicians
at the UW.  It will be on the domestic market "early next autumn at a cost of
under $1000," Cummings says.

[An untapped market for LaTex?  --JCS]

Jeff Stout    Electrons:, uw-beaver!bcsaic!jstout
              Molecules: Advanced Technology Center, Boeing Computer Services,
                         M/S 7L-64, P.O.Box 24346, Seattle, WA 98124-0346

Robert Tappan Morris indicted

Thu, 27 Jul 89 10:44:56 -0400
The 7/27/89 Boston Herald reports that Robert T. Morris has been indicted on
a single felony count of accessing without authorization at least six (!!)
university and military computers.  He therefore becomes the first person to
be charged under the "Computer Fraud and Abuse act of 1986", a dubious honor
at best. If convicted he faces a possible prison sentence of 5 years and a
possible $250,000 fine.

Re: UK Defence Software Standard

Mark Moraes <>
Thu, 20 Jul 89 10:18:58 EDT
You precisely underline the risk involved - that the software engineers
working on life-critical might not be trained in "modern software

One does not have to be an academic computer scientist to understand
recursion, dynamic memory allocation, multi-tasking, and interrupts.
One does not have to be an academic computer scientist to use them, or
to decide not to use them.

However, decisions to use or not use such techniques must be informed,
and made from knowledge, not ignorance. Turning one's back on new
techniques because they are risky in the hands of untrained people is
not the answer - training them in the new techniques is.

Yes, training people in software engineering is an expensive business
- it also takes time, and is an ongoing process. But if someone
involved in RISKy projects is not a top-flight software engineer,
isn't that a serious risk to the project? And to the lives that may
depend on it?

Re: UK Defence Software Standard

Douglas W. Jones <>
Fri, 21 Jul 89 10:03:16 CDT
The terms software engineering and software engineer have clearly gotten
completely out of control if people with AA degrees or less are calling
themselves software engineers.  It is my understanding that the ABET takes
a very strong stand on who should be allowed to call themselves an engineer.
If I remember correctly, they say that the term should only be applied to
those who have one of the following qualifications:

  1) People who have passed a state professional engineering examination.

  2) People who have graduated from an accredited 4-year engineering program.

  3) People who have graduate degrees.

In the past, I have had a fairly negative feeling towards this strict rule.
As a professor of computer science in the liberal arts college of a large
university, I've always had the feeling that it discriminated against graduates
of my program in favor of graduates of similar programs that happen (usually
for historical reasons) to be in engineering colleges.

I feel strongly enough about the misapplication of the term software engineer
that, if things continue to develop the way they are currently developing, I
would even be willing to urge state regulation of the use of the designation.

Consider an analogy:  The people who design the power distribution system for
a power plant are electrical engineers.  They have college degrees in
electrical engineering, they are usually fairly senior, and they usually have
state professional engineering certificates.  The people who build the power
distribution system are electricians working under the supervision of an
electrical engineer.  They may have AA degrees in engineering technology, and
they have passed a state or local electricians examination.

I do not object to someone with an AA degree in software technology helping to
write the software to control that power plant, but I do object to their
billing themselves as a software engineer, and I do object if the power company
puts them in charge of the design of such software.  This appears to be
precisely what is happening today.

Douglas W. Jones, University of Iowa,

polling vs. interrupts

Douglas W. Jones <>
Fri, 21 Jul 89 11:16:23 CDT
I have enjoyed the recent arguments about polling and interrupts that were
kindled by the UK defense software standards debate, but I have found them to
be incomplete.

I have written real-time software, I have worked on the design of real-time
multiprocessors, and this summer, I have even spent far too many hours counting
cycles, but I also like interrupts.

When I was involved with the Modcomp User's Group, and again, when I worked for
Rockwell International, I met many strong advocates of the view taken by the UK
software standards.  Most of them were older programmers who hadn't heard of
Dijkstra but had years of experience making reasonably complex real-time
systems work reasonably well.

Their arguments usually boiled down to the following:  When a program is
constructed as a single main polling loop and all action routines are called
from within this loop, it is easy to assure that the program meets real-time
constraints.  Each routine called from within the main loop can be given a
strict time limit, and it is fairly simple to show that each routine lives
within this limit.

Within action routines called from the main polling loop, some fairly simple
rules must, of course, be obeyed.  Straight-line code is easy to verify,
branching code is easy to verify, and definite loops can be verified, but
indefinite loops are forbidden.

If you look at typical real-time programs of the 60's and 70's, these rules
weren't much trouble.  User interfaces were crude at best, and most of the
processing was fairly simple feedback control with little algorithmic
complexity.  Unfortunately, many of the larger problems we face today are far
more complex, with significant algorithmic components.

The very coding constraints that allow straightforward verification that a
a program meets simple real-time constraints serve to obscure the algorithmic
structure of the program.  When one or more logical tasks within a real-time
program involve complex algorithmic structures, they must usually be recoded
using state machines that make a state transition each time they are called
from the main polling loop.

As a result, it remains easy to verify that the complex tasks do not consume
more than their allotted time slots in the main polling cycle, but that is
all.  All other aspects of the complex tasks are hidden in a mass of state
machines so that even simple questions can take hours to answer.  In fact,
this structure can even impede the verification that some real-time
constraints are met.  Consider the problem of verifying the real time
behavior of a logical task that, after detecting an event, must respond
after a computation that requires multiple iterations of the main loop.

Douglas Jones, University of Iowa,

Single Point of Failure for Internet Management

Kee Hinckley <>
Fri, 21 Jul 89 10:53:53 EDT
The Boston Globe today (Fri, July 21) reported that the GAA has recommended
that an advisory committee be set up to run the Internet since there was "no
one as the wheel" in the latest virus incident.  It seems to me that this
potentially slows down the response time of the Internet to such problems
and creates a single point of failure (cut out communication to the
committee and now no one knows what to do).

DARPA contract & AI for moving targets

20 Jul 89 08:19:00 PDT
Two points:

1. Many years ago, the single integrated target list was for a war,
 that included by implication nuclear war.  But even in nuclear war,
 NOT EVERY weapon used will be nuclear.  There are some missions
 where conventional albeit "smart" weapons would really be better.
 It follows that we - and they - really do need to target things
 that move; e.g., large ships, and mobile missile launchers.

2. A large ship is almost equivalent in population and technical
 complexity to a small town; e.g., 5000 "residents" with enough
 "restaurants" and "movie theaters" to serve them.
 Recent news item: The USSR is developing for deployment its
 first aircraft carrier.

The technical points of "how to select" targets are a fertile question for
RISKS.  If and when we want to debate the policy, maybe we should move that

Two-Word Last Names and Other Amusing Database Stories

Thu, 20 Jul 89 09:51 MST
Two amusing computer-related security stories from the Univ. of Colorado:

1.  Bank Card Numbers for Everyone:  Continuing Education offers community
courses and unlike other units of the university is therefore compelled to
accept bank cards for payment.  This necessity was overlooked when the new
student information system was created so no protected field was allocated to
hold bank card numbers and no otherwise unused field appeared to be big enough.
But someone cleverly decided to use an unused address field for this purpose
until it was discovered that almost anyone with any access to the system could
then read a student's name, address, and VISA number.

2.  Another Two-Word Last Name Problem:  The Colorado Association of
Research Libraries now offers an on-line database of citations for every
article in every journal any of the libraries receive.  It isn't as good
as services offered by DIALOG or ISI or other big commercial operations
but it is a boon to local researchers.  They offer it free to university
folks but want to sell the service to outside users.  Hence, all faculty
now need user ids.  They cleverly use SSN and last name and both are
displayed when you type them on a public terminal.  But mine wouldn't
work!  I called the CARL office and once I identified myself as a
confused faculty member the cheerful clerk gladly told me my proper user
id over the phone.  [I thought about asking her how she knew I was who I
said I was but the risks seem to be all theirs and not mine so I didn't
bother.]  It turns out one must add the prefix "A9/" to the SSN [maybe
they added that for security :-)].  But mine still wouldn't work.  Then
she discovered that on the university payroll tape that had been used to
create the user database my name had been entered as "Mc Clelland" so
that forevermore my CARL name would be "Mc".  That worked fine.

   Gary Mc [Clelland]

Credit card issuers invade cardholders' privacy

Andrew Klossner <>
Thu, 29 Jun 89 16:59:48 PDT
Excerpted from "The Facts About ... Credit Cards," in the April 1989
issue of "Vis a Vis" magazine, "The Magazine of United Airlines, Inc.":

     "Enhancement" is industry parlance for the tie-ins, upgrades,
     rewards, automatic insurance and warranty protection for products
     bought with the card.  Issuers continuously sweeten the
     enticements ...

     Shopping for clothes?  Traveling abroad?  Do you prefer bespoke
     British tailoring?  Country inns — in New England or France?
     Your card company will soon know a thing or two about your tastes
     in restaurants and may some day [sic] be a source of
     recommendations for lodging, dining and a host of other services.

     Card companies are investing huge sums of money to read and
     analyze your charge receipts.  The "enhancement wars" create handy
     perks, but the battle for the hearts and minds of cardholders also
     rages in computer banks across the country ...

     The payoff for issuers who successfully use technology to analyze
     customer spending will be tremendous, asserts John Love of "Credit
     Card News."  "This information is extremely personal to the
     customer," he says.  "He might begin to feel that his card company
     really understands him."

     Chenault of American Express says his company is "betting the
     ranch" on its $100 million Genesis Project.  The program's goal is
     to make sure the company's nearly 300 mainframes and minicomputers
     can create dossiers on the tastes of cardholders.  Says Chenault:
     "If a cardmembers is traveling to Paris, we could develop a
     personalized itinerary before he even gets there.  We'll know his
     tastes in restaurants, special interests and shopping, and we
     could work with establishments to arrange even big-ticket


  -=- Andrew Klossner   (uunet!tektronix!frip.WV.TEK!andrew)    [UUCP]
                        (   [ARPA]

Re: windowless cockpits

Andrew Klossner <>
Fri, 30 Jun 89 09:39:04 PDT
    "Video and graphics processing is performed, and digitized
    pictures are relayed to the helmet display."

It's the graphics processing that offers the most promise.  Some
projects (sorry, I have no references) are investigating the effect on
military pilot performance when the visual display is *simplified*, to
the point where important objects in the field of view are reduced to
wireframe figures, and unimportant objects are eliminated altogether.
Thus, an approaching mountain might look like an inverted cone sticking
up ahead of you; a river underneath (or civilians about to be bombed)
wouldn't be visible at all; and aircraft around you would show as stick
figures, perhaps with color coding to convey relative velocity,
friend-or-foe evaluation, etc.  An approaching missile might look like
a line growing toward you, just like it does in the "missile attack"
video games.

The win is that humans are better at pattern recognition when the
patterns are simple and the distractions are eliminated, especially in
time-critical situations.  Look at how well we do at those video games.

Another win is that, since the pilot no longer needs visual input
besides the (relatively low-bandwidth) wireframe presentation, it
becomes that much easier to move the pilot outside the plane, perhaps
to a bunker on the ground, and run the plane by remote control.  The
only important sensory input that would be missing is acceleration
(including gravity, "which way is down"), and good pilots learn to
distrust that anyway.

But there are still occasions when you need a full-video picture, such
as evaluating damage to an enemy aircraft (is it on fire?) or locating
an emergency landing site.  And simplified video presents new
opportunities for defensive counter-measures — you'd like the enemy's
system to classify your fighter as "unimportant," or to classify your
chass as "important."

    "... the possibility of crashing an airplane because of a
    failure in the video system, coupled with the inability to look
    out the window (because the plane doesn't have one) is

This risk should be kept in perspective.  For example, on a high
performance aircraft with forward-swept wings, if the computer handling
flight stability goes down, it doesn't much matter whether the pilot
can see or not; the plane is going to crash.

  -=- Andrew Klossner   (uunet!tektronix!frip.WV.TEK!andrew)    [UUCP]
                        (   [ARPA]

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