The RISKS Digest
Volume 19 Issue 46

Monday, 17th November 1997

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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Aviation: COTS ist zum Kotzen? Part I
Peter B. Ladkin
College web surveys hazardous to your server's health
Adam Elman
Thanksgiving in Microsoft Outlook 97: check your calendar
Martin Minow
Hackers break into Macedonian Foreign Ministry phones
Steven Slatem
First Y2K spam
Lloyd Wood
Fake flowers cost $19K: Nowak de-flowered?
Bear R Giles
Identity problem: Jim != James
Michael Zehr
Internet Explorer 4 buffer-overflow security bug fixed
Stevan Milunovic
Synergy between IE4 bug and Intel flaw
Per Hammer via Jonathan Levine
Fix for the new Pentium flaw
Workaround for the new Pentium flaw
John R Levine
Re: New Pentium flaw
Fred Gilham
Nicholas C. Weaver
Marco S Hyman
Steven O Siegfried
Jon Strayer
Pekka Pietik{inen
Netscape security curiosity
Jeff DelPapa
USENIX Security Symposium
Cynthia Deno
Info on RISKS (comp.risks)

Aviation: COTS ist zum Kotzen? Part I

"Peter B. Ladkin" <>
Wed, 12 Nov 1997 19:36:44 +0100
An article `Windows added to cockpit choices' in Flight International, 5-11
November 1997, p 25, explains that the US company Avidyne has certificated
an avionics system based on Windows NT. The hardware supplier is Electronic
Designs, who has recently received approval from the FAA (approval for what
is not specified). Avidyne is apparently working on Level-C approval, which
will allow use of its moving-map display for IFR navigation. One of the
benefits is said to be the wide range of interfaces available to other

This is for general aviation. The first Supplemental Type Certificate
(required FAA documentation for installation) is for a Mooney piston single.

One major drawback could arise from the hardware. It was pointed out in
RISKS-19.45 (many authors) that the Pentium and Pentium MMX chips may be
halted by execution of a single instruction in any mode, independent of any
memory protection in the operating system. This instruction (in machine
language) is F0 0F C7 C8 in hexadecimal.

If Electronic Design's box is Pentium-based, the FAA could therefore shortly
be asked to certificate a design for IFR flight that can be halted in
mid-use. Unavoidably. By a few lines of software that are trivial to
write. I would hope I am not alone in feeling very uncomfortable about the
precedent this might set for acceptance procedures for COTS products in
safety-related environments.

This is a static bug, so programs are already available (see RISKS-19.45 for
one) which sweep through your software to determine if this instruction is
somewhere therein. But I wonder if the FAA will insist that Avidyne install
such programs and make it a required part of the use of the equipment that
this program is run as part of the pre-flight check before flight under IFR?
However, even this does not guard against programs which dynamically
generate this instruction.

For the history of a dynamically-generated instruction that halted the
Shuttle flight-control software in 1981, recounted at length in the
Communications of the ACM 27(9), September 1984, pp.874-900, see our
compendium `Computer-Related Incidents with Commercial Aircraft' available

Peter Ladkin

College web surveys hazardous to your server's health

Adam Elman <>
Mon, 10 Nov 1997 16:23:08 -0800

Last week (3 Nov 1997), *USA Today* held a survey on the sports section of
their Web site asking readers to rate their favorite college fight songs.

Many college students and alumni consider their teams, marching bands, and
fight songs, as matters of strong personal pride.  Combine this with a high
level of technical expertise at many universities and a college student's
traditional predilection towards mischief, and it's not too surprising that
some anonymous fans apparently wrote scripts to automate voting, overloading
USA Today's web servers with traffic and forcing them to end the survey as
of 11/10/97.  According to the web page cited above, one Michigan fan voted
60,000 times in six hours; that's 167 times per minute, or 3 hits per
second; nearly any web server would be crushed uner that kind of load in
addition to normal traffic.

Similar events have happened before; in March 1996, ESPNet
( ) held a survey for the "Best College
Mascot;" their servers were brought down by poorly-written scripts run here
at Stanford rooting for Stanford's Tree mascot; the Tree was subsequently
banned by ESPNet from participation in future "Best Mascot" surveys for five
years.  (Reference in the Stanford Daily:

These surveys, of course, have no purpose other than entertainment; there
are no prizes other than pride for winning.  Hence, people who are
technically-literate enough to write automated voting scripts, but not
enough to realize their impact on a web server, feel no compunction about
what would otherwise be considered major "cheating."

Adam Elman, Software Developer, Highwire Press

Thanksgiving in Microsoft Outlook 97: check your calendar

Martin Minow <>
Fri, 14 Nov 1997 14:26:11 -0800
Robert X. Cringely's article begins at

"Still, there are some things a big company can do that a small band of
programmers could never hope to accomplish. This was best shown to me this
week by reader Brian P. McLean, who points out that according to his
Microsoft Outlook 97 scheduling/datebook application, Thanksgiving falls
this year on *Wednesday*, November 26.

"Thanksgiving has always fallen on Thursday before.
Wednesday may be an improvement. I don't know."

Hackers break into Macedonian Foreign Ministry phones

Steven Slatem <>
Fri, 14 Nov 1997 09:13:53 +0100
It was recently reported in the story "Hackers break into Macedonian
Foreign Ministry phones," by Vladimir P., Central & East European CrimiScope,,
and Central & East European Secure Systems News, that theft of telephone
impulses is a new kind of threat facing Macedonia.  Arabic speaking
criminals have cracked a simple 4-digit code on card-based telephones,
enabling them to call free-of-charge all over the world, according to CEE
CrimiScope.  In many cases, the default code of 1111 is never changed and
even when another code is set, it often remains unchanged for years. The
risk is not only that companies and organizations will lose financially due
to higher phone bills but also that they might be sharing their proprietary
information, and that of their business associates, with tech-savvy
listeners.  From the story: "All that a potential hacker needs to do is the
following: First, a call must be placed to the (inadequately) protected
telephone station (switchboard).  When the taped message starts playing, the
hacker dials a "nine" followed by the four-figure secret code number of the
telephone station.  If the code still happens to be the manufacturers
default code (1111) - the job is done!  However, if the code is not the
default, the hackers begin their guessing game." — Steven Slatem,, Editor-In-Chief, Central & East European
CrimiScope, Central & East European Secure Systems News,

First Y2K spam

Lloyd Wood <>
Fri, 14 Nov 1997 10:23:48 +0000 (GMT)
  [Lloyd sent a long registration form and questionnaire for the first
  Y2K-related spam he's aware of.    +44-1483-300800x3641,

MAKE MONEY FAST!!! fixing Y2K problems!

The 'Experience with programming is NOT required!/Experience with computers
is NOT required!/Experience with computers is needed!/Experience with
software is needed!' will give any RISKS reader pause for thought.

  [The questionnaire asks for your credit-card number, $24 to register
  you, for which you will be sent a test.  If you pass the test, you
  will be listed in their database as Y2K Test Certified along with
  your test score, which allegedly will be "helpful in selecting people
  for positions that might require a higher skill level."  They also
  want to know if you will be willing to travel in your new role as
  a Y2K expert.  PGN]

Fake flowers cost $19K: Nowak de-flowered?

Bear R Giles <>
Fri, 14 Nov 1997 15:17:43 -0700 (MST)
C|Net reports that the Craig Nowak, of C.N. Enterprises of San Diego, has
been ordered by a Travis County (Texas) district court to pay $19,000 in
damages for sending spam which incorrectly identified '' as the
originating domain.

The owners of that domain, Tracy LaQuey Parker and Patrick Parker, Zilker
Internet Park (their ISP), and the EFF-Austin sued for damages after they
were forced to deal with thousands of bounced messages — an onslaught which
temporarily took down their mail server [as noted in RISKS-19.19 and 20.]


Bear Giles <>

Identity problem: Jim != James

"Michael Zehr" <>
Wed, 12 Nov 1997 11:23:16 -0500
There is a small town in northern Pennsylvania where there is at least one
case of identical twins that are named Jim and James.  (The twins go to the
same hospital to receive their medical care which is how I know about the
situation.)  So far there are no known mishaps at the hospital regarding
their medical records, but surely it's an accident waiting to happen, both
at the hospital and in any other computer databases.

A few comments:

If Jim and James receive their first service from an organization at the
same time, that's safest for them since there will be two records set up
initially.  If Jim goes first and gets a record created and James then tries
to obtain service at a later date, it's more likely that their records will
be combined.

Ironically, this is one case that computers are likely to get right if left
to their own devices.  Computers easily recognize Jim != James.  But
computers are rarely left to their own devices and it is a human operator
who is likely to tell the computer to update the wrong record.  (Same
address, same birthdate, "same" name — they must be the same person!)

There is plenty of opportunity for mixups when Jim and James have an
interest in keeping the records straight.  Imagine if one of them tried to
create trouble for the other!

We'll probably hear about Jim and James again if they ever order
e-tickets on the same flight.

-Michael J. Zehr

Internet Explorer 4 buffer-overflow security bug fixed

Stevan Milunovic <>
Thu, 13 Nov 1997 00:41:05 -0800
Within 24 hours of being told about a buffer-overflow bug in Internet
Explorer 4 discovered by DilDog at the University of Massachusetts,
Microsoft announced a patch.  The bug resulted from a URL longer than 256
characters, which allowed IE4's HTML interpreter under Windows 95 version A
to arbitrary execute binary code at the end of the URL.  DilDog had noted
that the bug had existed for six months, and had survived Microsoft's
10,000-person beta test — despite this being a characteristic flaw that
should have been detected.  [Source: Hacker Reveals Serious Security Hole in
IE4, culled from pcworld online, 12 Nov 1997.  PGN Very Stark Abstracting]

Synergy between IE4 bug and Intel flaw

Jonathan Levine <>
Wed, 12 Nov 1997 08:27:05 -0700 (MST)
By now I'm sure you've heard about this delightful synergy:

> ------- Forwarded Message
> Date:    Tue, 11 Nov 1997 06:53:45 -0500
> From:    "Per Hammer" <>
> Subject: New IE4 security hole exploited ...
> The deal is, if your use a 'RES://' URL that us longer than 256 characters,
> byte 257 onwards will be executed as machine code. Now ... think ...
> F0 0F C7 C8
> Which is only slightly less malicious than deleting any files ...
> Per Hammer

Fix for the new Pentium flaw

"Peter G. Neumann" <>
Mon, 17 Nov 97 8:17:05 PST
Intel Corp announced that a fix to the Pentium & Pentium/MMX microprocessor
flaw has resulted from Microsoft, Sun, and others modifying their operating
systems to block fatal instructions.  See .

Workaround for the new Pentium flaw

John R Levine <>
Sat, 15 Nov 1997 00:20:58 -0500 (EST)
To my surprise, it turns out there's a fairly straightforward workaround for
the new Pentium flaw, and at least one vendor, BSDI, has already released
system patches.  Contrary to rumors, it doesn't involve turning off caches
or anything like that, it's a way of arranging the interrupts in a way that
preempts the hang with a higher priority interrupt.  I gather there's also
patches available for Linux.

Here we have kind of a reverse risk — the increasingly ubiquitous Internet
made it possible to diagnose the bug and distribute a fix in a day or two at
very low cost.

John Levine,, Primary Perpetrator of "The Internet for Dummies",
Information Superhighwayman wanna-be,, Sewer Commissioner

PS: I don't see any reason that the same technique wouldn't work in Windows,
though I can't see any evidence that Microsoft is doing anything about it.

Re: New Pentium flaw (RISKS-19.45)

Fred Gilham <>
Tue, 11 Nov 1997 17:40:09 -0800
Another case of the media `not getting it' about computers appeared in the
*San Jose Mercury* on 11 Nov 1997.  The report on the latest Pentium flaw
said that the flaw was exploitable by applications written in C or languages
derived from C (whatever that means).

Since it's unlikely that any C compiler will ever be so foolish as to
deliberately generate the particular instruction in question, this
misses the point.

What is perhaps more confusing is that I've heard that Microsoft's
implementation of Java will allow the execution of machine code.  A
malicious Web page could then become a Pentium-killer by including the
defective instruction in its Java code.  Thus the problem, while not present
in Java, could arise from executing a Java program.

I suspect the newspaper's confusion arose from the fact that an `exploit' of
the flaw was demonstrated by a small C program that coerced an array
containing a series of bytes that implemented the defective instruction into
a function call.  Including that C code snippet in a program would indeed
exercise the flaw.  But the flaw is C-related only in the sense that the
flaw is Java-related because it could be invoked in Microsoft's Java

-Fred Gilham

Re: New Pentium flaw (RISKS-19.45)

"Nicholas C. Weaver" <nweaver@hiss.CS.Berkeley.EDU>
Tue, 11 Nov 1997 17:57:49 -0800 (PST)
Not only can one create a C program to execute this opcode, such a program
doesn't actually have to contain the sequence F00FC7C8.  A program could
build this up by bitwise or arithmetic operations, which implies that
scanning programs like Sam Trenholme's won't find a properly written
malicious program.  Also, by simply using Emacs or another editor, one could
enter this string into an existing binary and not have to compile a line of
code.  Ahh, the possibilities.

Nicholas C. Weaver

  [The possibility of self-modifying code was noted by many others as well.

Re: New Pentium flaw

Marco S Hyman <>
Tue, 11 Nov 1997 20:30:44 -0800
In RISKS-19.45 a perl script to find the dreaded Pentium flaw was posted.
There is a risk that some might believe the script will protect their
systems.  False.  It is quite trivial to `hide' the killer code so a search
for 0xf0 0x0f 0xc7 0xc8 will fail.  Several such hidden exploits were
recently posted to the bugtraq mailing list.

What is interesting is that BSDI has just announced a binary patch to their
operating system that is supposed to cure the problem.  No information was
given as to the nature of the patch.  The release notification specifically

   We are not at liberty to discuss the mechanism of the workaround
   at this time.

More risks?

Re: New Pentium flaw (RISKS-19.45)

Steven O Siegfried <>
Wed, 12 Nov 1997 09:39:59 -0600 (CST)
Earlier, I'd written and RISKS-19.45 had reprinted:

>The following perl script, courtesy of Sam Trenholme via the security
>mailing list at Redhat Software is reported to find _all_ occurrences of
>this code sequence on systems running Linux...

As has been pointed out to me by Jeremy Radlow (, there's
really no way reliable way to detect this code sequence, since trivial
run-time manipulations of the sequence renders it invisible to simple
filters.  Therefore, I'd encourage readers _not_ to rely exclusively on that
perl script to catch the problem.

Steve Siegfried

Re: New Pentium flaw

Jon Strayer <>
Thu, 13 Nov 97 09:11:18 -0500
While I'd rather there wasn't "halt and catch fire" instruction for the
Pentium, programs that crash the PC aren't exactly rare.

Jon Strayer, Software Solutions Group, Ameritech, Indianapolis   (317) 265-4037

Re: New Pentium flaw

"Pekka Pietik{inen" <>
Fri, 14 Nov 1997 02:56:02 +0200
The recent Pentium crash flaw scared quite a lot of people.  Fortunately
there was an acceptable workaround this time
(,4,16312,00.html), but it still gives us
something to think about.

Hardware is getting more and more complex and keeping serious bugs out of it
is getting quite difficult.

Imagine a bug in a popular processor that would let users run privileged
commands (there's no way the operating system can stop broken hardware from
doing anything it likes).  The bug would be impossible to fix without
replacing the chip (even with these new microcode update possibilities that
newer chips like ppro/pII have, another risk by itself, although I believe
the updates are not permanent, but reloaded each time the machine boots
making the problem very small). Obviously replacing millions of chips is
extremely costly.

A bug like this would basically make every modern secure multiuser operating
system that runs on that processor into a multiuser windows 95. Even if you
can trust the users, there's always some static buffer in a program (web
browser, mail reader, first alpha version of someones latest project) that
malicious people can overflow from the outside and thus run their code and
do whatever they want with the machine (without the hardware bug the damage
would be limited to one user)

The risk should be obvious, a single serious flaw in a popular processor
could have some very dramatic effects (there are millions of Pentiums out
there, many of which are in extremely critical places)

Pekka Pietikdinen, Net People Ltd., Oulu, Finland

Re: New Pentium flaw (RISKS-19.45)

Wed, 12 Nov 1997 08:49:44 -0500
Here is how to use DEBUG to create a DOS executable that exercises the new
flaw. DEBUG is available on DOS, Windows 3.x/95/NT and OS/2, and maybe others.
At the command prompt, do the following:

-e 100 f0 0f c7 c8
-r cx
CX 0000
Writing 00004 bytes


Netscape security curiosity

Jeff DelPapa <>
Thu, 13 Nov 1997 16:09:33 -0500
  [An earlier version of Jeff's message appeared to have identified
  a possible denial of service problem.  After several iterations with
  a few of the respected occasional RISKS referees, this is the upshot
  of what apparently really happened.  PGN]

A co-worker who wishes to remain anonymous came to me with a problem.  He
had been visiting sites that he likely should not have, and somehow wound up
with an advertisement on his background screen, one that was rather
inappropriate on company equipment.  It took some digging to find out how it
came to pass.

A quick look at settings showed that the display settings had been changed
to make "netscape wallpaper" the default background.

Apparently what happened was a simple UI slipup. He must have clicked right
on a picture, and somehow managed to use the "Set as Wallpaper" button.
given that it isn't the default action, he must have been waving the mouse
pretty violently.  This command doesn't require a confirmation, so he might
not have noticed it.  It's still a risk: things that don't have immediately
visible results should confirm.

USENIX Security Symposium

Cynthia Deno <>
Mon, 10 Nov 1997 21:58:30 -0800
26-29 Jan 1998, San Antonio, Texas
Marriott RiverCenter Hotel
Program Chair:  Avi Rubin, AT&T Research Labs
Sponsored by USENIX, the Advanced Computing Systems Association
In cooperation with the CERT Coordination Center

Register now online:
Early registration discount deadline:  January 5, 1998

Learn about the newest tools in tutorials, hear the latest solutions offered
by researchers, and talk with some of the leading lights in the security
community.  Speakers include: Bill Cheswick, Carl Ellison, Dan Geer, Arjen
Lenstra, Alfred Menezes, Clifford Neuman, JoAnn Perry, Marcus Ranum, Jon
Rochlis, Avi Rubin, Shabbir Safdar, Bruce Schneier.  Tutorial topics
include: Java, NT, and Web Security; Cryptography; Certification; How to
Handle Incidents; What Every Hacker Already Knows

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