The RISKS Digest
Volume 5 Issue 71

Monday, 7th December 1987

Forum on Risks to the Public in Computers and Related Systems

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

Please try the URL privacy information feature enabled by clicking the flashlight icon above. This will reveal two icons after each link the body of the digest. The shield takes you to a breakdown of Terms of Service for the site - however only a small number of sites are covered at the moment. The flashlight take you to an analysis of the various trackers etc. that the linked site delivers. Please let the website maintainer know if you find this useful or not. As a RISKS reader, you will probably not be surprised by what is revealed…


The Amiga VIRUS (by Bill Koester)
Bernie Cosell
Radar's Growing Vulnerability
Computerized vote counting
Lance J. Hoffman
United Airlines O'Hare Sabotage?
Chuck Weinstock
Re: Whistle-blowers who (allegedly) aren't
Jeffrey Mogul
In Decent Alarm
Bruce N. Baker
Need for first-person anonymous reporting systems
Eugene Miya
Apollo 11 computer problems
Michael MacKenzie
Interconnected ATM networks
Win Treese
Can you sue an expert system?
Gary Chapman
Jerry Leichter
Bruce Hamilton
What this country needs is a good nickel chroot
Bob English
Info on RISKS (comp.risks)

The Amiga VIRUS (by Bill Koester)

Bernie Cosell <cosell@WILMA.BBN.COM>
Mon, 7 Dec 87 0:25:23 EST
From: bill@cbmvax.UUCP (Bill Koester CATS)
Newsgroups: comp.sys.amiga
Subject: Amiga VIRUS
Date: 13 Nov 87 19:32:05 GMT
Organization: Commodore Technology, West Chester, PA

                   THE AMIGA VIRUS - Bill Koester (CATS)

When I first got a copy of the Amiga VIRUS I was interested to see
how such a program worked. I dissassembled the code to a disk file and
hand commented it. This article will try to pass on some of the things
I have learned through my efforts.

       1) Definition.  2) Dangers.  3) Mechanics 4) Prevention

1. - Definition.

   The Amiga VIRUS is simply a modification of the boot block of an existing
DOS boot disk. Any disk that can be used to boot the Amiga (ie workbench)
has a reserved area called the boot block. On an Amiga floppy the bootblock
consists of the first two sectors on the disk. Each sector is 512 bytes long
so the boot block contains 1024 bytes. When KickStart is bringing up the
system the disk in drive 0 is checked to see if it is a valid DOS boot disk.
If it is, the first two sectors on the disk are loaded into memory and
executed. The boot block normally contains a small bit of code that loads
and initializes the DOS. If not for this BOOT CODE you would never see the
initial CLI. The normal BOOT CODE is very small and does nothing but call
the DOS initialization. Therefore, on a normal DOS boot disk there is plenty
of room left unused in the BOOT BLOCK.

   The VIRUS is a replacement for the normal DOS BOOT CODE. In addition to
performing the normal DOS startup the VIRUS contains code for displaying
the VIRUS message and infecting other disks. Once the machine is booted from
an infected disk the VIRUS remains in memory even after a warm start.
Once the VIRUS is memory resident the warm start routine is affected, instead
of going through the normal startup the VIRUS checks the boot disk in drive
0 for itself. If the VIRUS in memory sees that the boot block is not
infected it copies itself into the boot block overwriting any code that was
there before. It is in this manner that the VIRUS propagates from one disk
to another. After a certain number of disks have been infected the VIRUS
will print a message telling you that Something wonderful has happened.

2. - Dangers.

   When the VIRUS infects a disk the existing boot block is overwritten.
Since some commercial software packages and especially games store special
information in the boot block the VIRUS could damage these disks. When the
boot block is written with the VIRUS, any special information is lost
forever. If it was your only copy of the game then you are out of luck
and probably quite angry!!

3. - Mechanics.

   Here is a more detailed description of what the virus does. This is
intended to be used for learning and understanding ONLY!! It is not the
authors intention that this description be used to create any new strains of
the VIRUS. What may have once been an innocent hack has turned into
a destructive pain in the #$@ for many people. Lets not make it any worse!!

   a.)   Infiltration.

            This is the first stage of viral infection. The machine is
         brought up normally by reading the boot block into memory. When
         control is transferred to the boot block code, the virus code
         immediately copies the entire boot block to $7EC00, it then JSR's
         to the copied code to wedge into the CoolCapture vector. Once
         wedged in, control returns to the loaded boot block which performs
         the normal dos initialization. Control is then returned to the

   b.)   Hiding Out.

            At this point the system CoolCapture vector has been replaced
         and points to code within the virus. When control is routed through
         the CoolCapture vector the virus first checks for the left mouse
         button, if it is down the virus clears the CoolCapture wedge and
         returns to the system. If the left mouse button is not pressed
         the virus replaces the DoIO code with its own version of DoIO
         and returns to the system.

   c.)   Spreading.

            The code so far has been concerned only with making sure that
         at any given time the DoIO vector points to virus code. This is
         where the real action takes place. On every call to DoIO the virus
         checks the io_Length field of the IOB if this length is equal to
         1024 bytes then it could possibly be a request to read the boot
         block. If the io_Data field and A4 point to the same address
         then we know we are in the strap code and this is a boot block
         read request. If this is not a boot block read the normal
         DoIO vector is executed as if the virus was not installed. If we
         are reading the boot block we JSR to the old DoIO code to read
         the boot block and then control returns to us. After reading,
         the checksum for the virus boot block is compared to the checksum
         for the block just read in. If they are equal this disk is already
         infected so just return. If they are not equal a counter is
         incremented and the copy of the virus at $7EC00 is written to
         the boot block on the disk. If the counter ANDed with $F is equal
         to 0 then a rastport and bitmap are constructed and the message
         is displayed.

   d.)   Ha Ha.

            < Something wonderful has happened >
            < Your AMIGA is alive!!! >
            < and even better >
            < Some of your disks are infected by a VIRUS >
            < Another masterpiece of the Mega-Mighty SCA >

4. - Prevention.

   How do you protect yourself from the virus?

      1) Never warm start the machine, always power down first.
         (works but not to practical!)

      2) Always hold down the left mouse button when rebooting.
         (Also works, but only because the VIRUS code checks for
          this special case. Future VIRUS's may not!)

      3) Obtain a copy of VCheck1.1 and check all disks before use.
         If any new virus's appear this program will be updated and released
         into the public domain. VCheck1.1 was posted to usnet and will
         also be posted to BIX.
         ( Just like the real thing the best course of action is
           education and prevention!)

Bill Koester — CBM  <>Amiga Technical Support<<
                     UUCP  ...{allegra|burdvax|rutgers|ihnp4}!cbmvax!bill 
             PHONE  (215) 431-9355

Radar's Growing Vulnerability

Peter G. Neumann <>
Mon 7 Dec 87 13:52:21-PST
For readers of SCIENCE, the 27 November 1987 issue (p. 1219) has a nice article
by Stephen Budiansky (titled asa the Subject line above) on the problems of
defensive radars.  ``As weapons become smarter, they learn to "see" radar beams
as pathways to their target, gaining an advantage over defensive systems.''
The caption on a picture of the smoking HMS Sheffield says that it ``was hit in
the Falkland Islands war in 1982 when its radars attracted a rocket launched
from a fighter plane 20 miles way.''  (RISKS readers will recall that the
British investigation concluded that the Sheffield's own radars were jammed by
a communcation back to London that was being held at the time.)

Computerized vote counting

Mon, 7 Dec 1987 14:22 EST
I have just completed a study of computerized vote-counting systems.  The
report, based on a workshop of experts in election administration and
computer security, presents recommendations to improve the security and
reliability of computerized vote-counting systems.  The recommendations are
organizational, not technical, because that is where the most important
problems lie.  However, five focus papers are included, including one by
Willis Ware on "A Computer Technologist's View".  For a free copy, please
send a snail mail or email request with your complete snail mail address to

                Election Computer Security Project
                Dept of Electrical Engineering & Computer Science
                The George Washington University
                Washington DC 20052

Lance Hoffman   (LANCE@GWUVM.BITNET)

United Airlines O'Hare Sabotage?

Chuck Weinstock <weinstoc@SEI.CMU.EDU>
Mon, 07 Dec 87 17:36:28 EST
On December 3, I was traveling from California to Pittsburgh via Chicago on
United.  My inbound flight came in at an E gate and my outbound left from a
new C gate.  If an agent hadn't been there to greet the plane, I wouldn't
have known it because the monitors were out.  I got to the C terminal and
the monitors there were on but unreadable due to jiggle (all of them.)  I
went to a pay phone and could not get a dial tone (on any of them.)  I
boarded my flight and we sat for an extra 20 minutes because "a cable had
been cut" and thus they were unable to calculate the amount of fuel to load.
I surmised that this was a landside cable and that all of the above events
were somehow related.

I decided to call United today and learned that my surmise was true.
Multiple fires in the basement of terminal 2 caused both AT&T and United
wires to be severed.  The former knocked out the pay phones, and the latter
the airline's ability to communicate with it's computers across town.

It also seems that, at the new terminal at least, there is an automatic,
underground fueling system which shut off once it detected a fire. Technicians
were able to override the interlock once they determined that there was no
danger due to the fire, and the pilots apparently had to do fuel calculations
manually.  Given that United has a new computerized baggage routing system at
O'Hare, I'm really surprised that my luggage made the connection ok.

175 flights were delayed on Thursday and Friday morning.  Officials suspect
arson though the United spokesman I talked to could not suggest a motive.
Full phone service to the terminal was not restored until Friday evening.
United is awaiting licensing of a microwave system in the near future to leave
themselves less vulnerable to this sort of sabotage.

Re: Whistle-blowers who (allegedly) aren't

Jeffrey Mogul <>
7 Dec 1987 1646-PST (Monday)
Henry Spencer writes:
    Maybe I am just being picky about this, but it still makes me see red when
    I see Boisjoly described as a "whistle-blower".  Boisjoly is the man who
    could have blown the whistle BUT DIDN'T, and seven astronauts died as a
    result.  Boisjoly was the engineer who told MT management "don't launch",
    was told "put on your management hat", did so, and changed his expert
    professional opinion 180 degrees to match his hat color...

I recently saw a videotape of Boisjoly's appearance at MIT.  I think Henry is
somewhat confused; Boisjoly made it quite clear that it was another person
(higher up in the management structure) who was told to "put on your
management hat" and who in fact reversed his engineering opinion (and, as I
recall, that was enough to overrule the other engineers).  True, Boisjoly did
not blow the whistle (i.e., go outside Morton Thiokol) at this point, but he
says that he and other engineers were quite upset at the time, and he referred
to a notebook entry he made that night expressing his fear about the next
day's launch and his unease at the management actions.

What he did blow the whistle on was a coverup by Morton Thiokol of the
long trail of engineering dissent over the previous year or so, due
mostly to Boisjoly and several colleagues.

It is hard, even in hindsight, to say that Boisjoly himself did not do all he
should have done on the eve of the launch, and is therefore criminally liable
(I'll agree that his management was at fault).  Who could he have gone to with
just a few (nighttime) hours before the launch, with no irrefutable evidence,
and no support from either his management or from NASA?  (It has been
suggested that NASA was under pressure from the White House to launch in time
for the State of the Union speech that day; Boisjoly wouldn't have found many
politicians willing to delay the launch!) In hindsight, most people would
agree that he was right to object, but at the time he would have been rather

I think it is important to stress that Boisjoly (if his own account is
trustworthy) was not "turning state's evidence after the fact," but rather
blowing the whistle on a coverup of his internal dissent.
                                                            -Jeff Mogul

P.S.: This videotape is fascinating and a lot more damning of both
NASA and Morton Thiokol than my summary is.  It's also quite sad; in
the process of urging a room full of MIT students to be prepared to
blow whistles, Boisjoly also conveys the strong personal costs of doing
so.  I'll try to find out how people can obtain a copy.

In "Decent Alarm"? (Re: Mariner 1 or Apollo 11? in RISKS-5.70)

Bruce N. Baker <BNBaker@KL.SRI.COM>
Mon 7 Dec 87 10:46:49-PST
The idea of a "decent alarm" conjures up all sorts of images and fantasies for
me, but perhaps Brent Chapman meant "descent alarm".
    [Skunked again.  Thanks for descenting.  PGN]

Need for first-person anonymous reporting systems

Eugene Miya <>
Mon, 7 Dec 87 09:16:59 PST
The Mariner and F4 canopy (not computer related) stories appear to be
indicative of certain types of bureaucracies.  While I investigate the
Mariner story (I have two leads at the moment), I think that it appears to
me that normal academic reporting and publication procedures fail us in
these matters.  Bureaucracies don't like negative subjects to be remembered
(almost, I just remembered today is Dec. 7).

If we are ever going to progress out of the software muck, we are going to
have to come up with mechanisms to replace all of our ancedotal information
with better information.  This has to be separate from any type of watch-dog
enforcement like "Golden Fleeces," ombudsmen or Inspector Generals.  We have
to throw out hearsay.  Perhaps an anonymous Email system (lots of inherent
problems) to a third party? I don't know, but it's something to think about.

--eugene miya

Apollo 11 computer problems

Michael MacKenzie <>
Mon, 7 Dec 87 12:11:57 EST
Exerpt from Apollo, Expeditions to the Moon,
Scientific and Technical Information Office, NASA, Washington D.C., 1975

During the landing of Apollo 11

Michael Collins:

At five minutes into the burn (6000 feet above the surface)
... "Program alarm", barks neil, "Its a 1202", what the hell is that?
I don't have the alarm numbers memorized for my own computer, much less
for the LM's  I jerk out my checklist and start thumbing through it, but before
I can find 1202 Houston say, "Roger, we're GO on that alarm" no problem
in other words.  My checklist says 1202 is an "executive overflow" meaning
simply that the computer has been called upon to do too many things at
once and is forced to postpone some of them.  A little farther, at just
3000 feet above the surface the computer flashes 1201, another overflow
condition, and again the ground is superquick to respond with assurances.

Interconnected ATM networks

Sun, 6 Dec 87 22:22:52 EST
[Based on an article in the _Boston_Globe_, 12/5/87, p.1]

In Massachusetts now, there is a great deal of competition for ATM networks.
BayBanks is by far the largest, and many other banks have joined together
in a network to compete with BayBanks in sheer number of machines.  BayBanks
recently joined NYCE, a network of ATM's in New York.  The Bank of Boston
also joined, so now Bank of Boston cards work in BayBanks machines.

When the Globe contacted BayBanks, they refused to acknowledge it until
told that the Globe had photographed an editor actually using a Bank of Boston
card in a BayBanks machine.  Pressed further, a BayBanks spokesperson
admitted that it worked, and said that they didn't know NYCE was active yet.

    Win Treese
    MIT Project Athena

Litigation over an expert system

Gary Chapman <>
Mon, 7 Dec 87 10:28:51 PST
I am not an attorney, but I worked as a consultant in product liability cases
for eight years, and I have some comments on the question posed in RISKS about
whether one can sue for damages caused by the use of an expert system.

First, who do you sue?  Answer:  everybody.  As long as the parties mentioned
in the case of a financial analyst expert system are individuals or distinct
corporate entities, they can be sued and they probably will be.  This is why in
large product liability cases the defendants can be numerous--in cases
involving DES, for example, (the drug, not the encryption system) there are
literally hundreds of defendants.  There does not even have to be a real legal
basis for suing a defendant; it becomes incumbent on the defendant to convince
the court that there is no legal basis for the lawsuit in a motion for summary
judgment.  There are even attorneys who specialize in finding defendants who
can be sued--for example, in one case I know about, which involved a high
school football player who had been paralyzed from a tackle injury during a
game, a special attorney was brought in to find potential defendants, and the
plaintiff wound up suing the NCAA, which had drafted the rules for playing
football that were used by the plaintiff's school district.

One of the few ways in which a person or a corporation can be guaranteed
protection from litigation is an indemnity agreement, or indemnity clause in a
contract, which explicitly says that in the event of a lawsuit, one of the
contracting parties will pick up the legal defense of the other, including all
expenses and all judgments.  These are pretty rare.

It is correct to assume that a disclaimer, or a warning, or a "terms of
agreement" document such as is commonly found in software packages, is no
protection against a lawsuit or a judgment against the developer.  It is up to
a judge or jury to decide whether the warning was adequate, whether it was
relevant to the damages, and even whether it was presented to the user in a way
that was likely to have actually "warned" the consumer about the use which
produced the damages.  For example, in a couple of cases I worked on, the
plaintiffs brought in a psychologist who specialized in the visual impact of
signs--she consulted with municipal transportation systems on how to design
signs on subways that would get across essential information, for example.
This psychologist would frequently testify that a warning on a product was
ineffective because of the way it was packaged or designed.  It is hard to
estimate the effect of her testimony on a jury--sometimes the plaintiff won,
sometimes the defense won.  But this is an illustration of what one is likely
to be up against in a case involving large damages.

In another illustration, it often comes up in product liability cases involving
drugs that the warnings issued by drug companies and published in a standard
reference work called the Physicians' Drug Reference, or PDR, are so dense and
so full of information that they no longer convey a "warning" that is
intelligible to anyone.  Nevertheless, if the drug companies fail to include
any particular bit of information then they may be liable for failing to
provide a warning for something they knew about.

A jury may award a defendant a judgment even when there was a warning or a
terms of agreement document.  The defendant may then appeal the judgment based
on a claim that the defendant did everything in his power to avoid the
damages--for example, a lawn mower company put a big, nasty looking warning on
some part of the lawn mower that said don't do such and such because you may
get your hand caught in there and lose some fingers, but the plaintiff did it
anyway and for some reason the jury decided he should get some money from the
defendant.  But appeals are expensive, and it's likely that the defendant and
the plaintiff will settle the case for some dollar figure, and perhaps the
money will be paid by an insurance company.  There is not much one can do to
predict what a jury will decide, even in the most straightforward cases.  I
remember asking one juror why she voted the way she did, and she said that she
understood that she was supposed to give *someone* some money, and she thought
the defendant could pay more than the plaintiff could.  A jury may also decide
that a warning could have been better, but that the plaintiff was also at least
partially responsible for his injury through "contributory negligence," so the
dollar amount of the judgment may be lower because of this.

In California, where I live, there is a goofy law that if one of the defendants
in a multi-party suit is judged to have been responsible in any way, that
defendant is liable for the percentage of responsibility, no matter how small.
In other words, if the jury decides that defendant A is 99% responsible, and
defendant B is only 1% responsible, and the judgment is $10 million, defendant
B has to pay the plaintiff $100,000.

I don't know of any cases of product liability involving damages alleged to
have occured because of the use of an expert system, but the law is likely to
be the same for such cases as it is for any other product liability case.

Mon, 7 Dec 87 10:53 EST
Subject: re:  Can you sue an expert system

In RISKS-5.69, Barry Stevens becomes another in a long line of people to raise
the question "If an expert system gives bad advice, who can I sue?"  I find it
extremely disturbing that this is considered an interesting question by
ANYONE, let alone by technically sophisticated people.  It is a symptom of the
pervasiveness of our misplaced trust in buzzwords and, more generally, in
computers:  If the computer said it, it MUST be right.

We have no idea how to build an expert system with anything you would want to
call "understanding" or "responsibility" - or even "intelligence" - in any but
the most narrow sense.  There is no indication that we will be able to build
such a system any time soon.  An expert system is a clever way of encoding a
textbook and some guidelines.  If well designed, it happens to be a lot easier
to use than the typical textbook - but then again there are good textbooks and
poor textbooks.  It should make no more sense to sue an expert system than it
does to sue a textbook.  It should make no more sense to sue a vendor of
expert systems than it does to sue a publisher or a bookstore because of
inaccurate information in one of the books they sell.  It should make no more
sense to sue the "knowledge engineer" who did the fairly routine work of
organizing data from a group of experts into an expert system than it would to
sue an editor of an encyclopedia.  Finally, it should make no more sense to
sue the expert who contributed to an expert system than it does to sue the
author of an encyclopedia article.

As a general rule, it's almost impossible to sue someone for advice offered
in a book.  You need a much closer relationship with the expert - the expert
has to hold himself up not just as an expert "in general", but as an expert in
your particular problem.  In paying for him to work on your particular prob-
lem, you are creating expectations and obligations that go far beyond what
you can expect from an author of a book.

In our litigious society, someone WILL sue over the advice given by an expert
system.  They'll sue everyone they can.  They may even win, eventually.  If
they do it will be a sign that enough advertising, enough magazine articles,
enough speeches on how "intelligent" expert systems are have been given that
the courts have decided that people are legimately entitled to view this claim
as more than mere "seller's talk".  The first such case to be upheld is likely
to see the death of the expert systems business:  We do not know how to build
expert systems that can come close to living up to the expectations being
raised for them.  No one will be able to afford the resulting liabilities.
From my point of view, if it ever came to that, it would be a result richly
deserved by an industry that has lived on hype.  What disturbs me is that it's
unlikely the legal system, should it ever start on this path, will draw quite
the distinctions we in the business draw between expert systems and other
kinds of applications.  Would you like to be personally liable because the
database program you wrote didn't deal with spelling errors and as a result
someone missed an incorrectly-typed reference in an on-line catalog and was
somehow injured as a result?

There is SO much hype about computers and their miraculous powers, and SO much
of a willingness to believe it on the part of the public, that I think we as
professionals have an obligation to tell people, at every opportunity, just
how limited our real abilities are, and are likely to remain in the forseeable
future.  Speculations about the legal liabilities of AI's are fine as philo-
sophy, but as anything more than speculation about possible futures, they are
uninformed about either the technical or legal realities.  If they lead people
to place their trust in such systems inappropriately, then can be downright
                            — Jerry

Re: Can you sue an expert system?

7 Dec 87 11:49:47 PST (Monday)
No new law needed here.  I'm a layman, not a legal scholar, but it seems to me
that an "expert system" is precisely analogous to a book.  The only difference
with a book is that you have to do all the "if-then" calculations yourself
("if your net worth according to this formula is > X, then turn to page

What this country needs is a good nickel chroot (Re: RISKS-5.63)

Bob English <lcc.bob@SEAS.UCLA.EDU>
Mon, 30 Nov 87 12:33:02 PST
> From: "Joseph G. Keane" <>
> Subject: Re: "UNIX setuid stupidity" (RISKS-5.57)
> The designers of UNIX considered that a trusted program may wish to allow 
> operations only on a certain part of the directory tree.  So they provided 
> the `chroot' system call, ...   --Joe

Chroot doesn't work very well.  Since the super-user can create device inodes,
it can access or modify any disk area, regardless of the limitations enforced
by the new root.  'Chroot', by itself, will not prevent a determined invader
from penetrating to the rest of the system.  It does, however, prevent
penetrations based solely on moving through ".."
     [To those of you who contributed on this topic, I STILL have a backlog
     of messages waiting for me to sort out the wheat from the chaff.  PGN]

Please report problems with the web pages to the maintainer