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Research group of Prof. Peter B. Ladkin, Ph.D.
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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 16, Issue 17

Friday 17 June 1994

Forum on Risks to the Public in Computers and Related Systems

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


o Poulsen guilty of L.A. charges
Mich Kabay
o Counterfeit graduation tickets
Mich Kabay
o "Virtual Billboard" on TV
R. Peter Jackson
o Misdirected Mail
Jeffrey Austen
o Revenue Canada database allows birthday change
John Howard
o NIST Response to Blaze Attack on Clipper
Ed Roback
o ROLM phones and "Do Not Disturb": how to lose calls
Rob Levandowski
o A320 hull losses: Lies, damned lies and statistics
Pete Mellor
o Info on RISKS (comp.risks), contributions, subscriptions, FTP, etc.

Poulsen guilty of L.A. charges

"Mich Kabay [NCSA Sys_Op]" <75300.3232@CompuServe.COM>
16 Jun 94 18:01:35 EDT
     From the United Press International newswire (94.06.14 @ 18:45 EDST) via
     Executive News Service (GO ENS) on CompuServe:
     "Hacker Pleads Guilty to Fraud", By ELKA WORNER
       LOS ANGELES, June 14 (UPI) -- A computer hacker accused of breaking into
       computer systems to rig promotional contests at radio stations, eavesdrop on
       private citizens and thwart police investigations, pleaded guilty Tuesday to
       fraud.  Kevin Poulsen, 28, of Menlo Park, faces 40 years in prison and a
       $1,750,000 fine when he is sentenced Oct. 17.
         He pleaded guilty in federal court to computer fraud, interception of wire
       communications, mail fraud, money laundering and obstruction of justice.
     The author summarizes the case against Poulsen [I added details she didn't
     o	[manipulated the phone systems to cheat in radio-station call-in
     contests that awarded prizes to a specific caller in sequence]; he stole "two
     Porsches from radio station KIIS-FM, $20,000 in cash from KPWR-FM and at least
     two trips to Hawaii and $2,000 in cash from the same station."
     o	used lies and counterfeit IDs to claim and then sell his prizes.
     o	uncovered FBI-run businesses, spotted FBI wiretaps and listened in on
     conversations of ordinary citizens.
     o	called a confederate "minutes after his arrest to ... hide the
     computers used in his illicit activities."
     o	lived on the run for 18 months after being indicted in San Francisco
     by a grand jury until his arrest in April 1991 .
     o	in July 1994, he will be tried "on 18 counts of telecommunications and
     computer related fraud, including charges that he stole Pacific Bell access
     codes to invade an Army computer network and to obtain information used in FBI
     investigation of former Philippine President Ferdinand Marcos."
     o	worked for the Soviet consul in S.F. by obtaining unpublished telephone
     Michel E. Kabay, Ph.D. / Dir Education / Natl Computer Security Assn

Counterfeit graduation tickets

"Mich Kabay [NCSA Sys_Op]" <75300.3232@CompuServe.COM>
16 Jun 94 18:01:29 EDT
     From the Reuter newswire (94.06.14 @ 14:25 EDST) via Executive News Service
     (GO ENS) on CompuServe:
         HANOVER, N.H., June 14 (Reuter) - A former Dartmouth College student was
     arrested for selling counterfeit graduation tickets for the event at his Ivy
     League alma mater, police said Tuesday.  Corby Edward Page, 23, a computer
     programmer from Houston, Texas and a 1992 Dartmouth graduate, admitted to
     making the fake tickets on his computer and selling them before the June 12
     graduation for $15 each, said Hanover Police Sergeant Christopher O'Connor."
     According to the story, a student who bought a bogus ticket "called police
     after noticing the fake tickets were different from the real ones."  The idiot
     grad was caught "in the lobby of the posh Hanover Inn, opposite the Dartmouth
     campus, as he sold tickets, police said."
     He was charged with fraud.

"Virtual Billboard" on TV

"R. Peter Jackson" <>
Thu, 16 Jun 1994 23:07:10 -0700 (PDT)
     On Wednesday, June 15, 1994, the Los Angeles Times reported on page D7 in
     their relatively new weekly section called "The Cutting Edge
     Computing/Technology/Innovation" the following:
     	"Virtual Billboard" Is Sign of the Times	
     Baseball teams would love the revenue from behind-the-batter billboards, and
     advertisers like the idea of being on screen without fear of remote-control
     zapping. But purists denounce the idea as antithetical to the tradition of the
     game, and some players say the signs make it harder to see the ball.
     Now inventors have devised a system that will create electronic billboards
     visible only to people watching on TV. Princeton Electronic Billboards Inc. in
     Princeton, N.J., has been testing "virtual billboards" with the Baltimore
     Orioles and its telecasters. Working with the David Sarnoff Research Center,
     the firm developed a computerized system that inserts images electronically
     into TV shows.
     Before a game, the TV cameras scan the arena and "memorize" features of the
     park, such as creases in the padded wall behind home plate and other
     boundaries that define a virtual billboard. When the camera passes those
     features during the telecast, the system inserts the sign, or the part of it
     visible in the camera's frame of reference.
     Ballplayers on the field appear to walk in front of the sign. Ideally, the TV
     audience will be unable to tell whether the billboard hangs in the ballpark or
     only in cyberspace. Local sponsors could buy a billboard in a national
     telecast, and a national advertiser could deliver different messages in each
     Princeton Electronic hopes to make the system available commercially before
     the baseball season ends this fall."
     It seems obvious that the RISKS increase as the truth of the picture in the TV
     medium can be selectively and partially modified. It is difficult enough now
     for many people to tell whether what is seen on TV is real or fake [note the
     many similarities between national network TV news, major metropolitan network
     news and the recreated news in Hard Copy and its several competitors.]
     R. Peter Jackson, Mariposa Computer Services, 982 Jimeno Road, P. O. Box 149,
     Santa Barbara, California 93102-0149 USA   1-805.963.4305  <>

Misdirected Mail

Jeffrey Austen < >
Thu, 16 Jun 1994 11:24:16 -0600
     I received the following in the mail the other day.  Quite amusing.  I wonder
     if the CIA would send out a similar message if one of their secrets got out?
     >One of IBM's electronic mail distribution nodes experienced a
     >problem routing mail from Wednesday June 8, 1994, through
     >approximately 7:00pm Thursday June 9, 1994.  This may have
     >resulted in your having received proprietary information that
     >was not intended for you.  If you have received such
     >information, please return it to the Internet address:
     >without retaining any copies of it.   If you have already
     >destroyed or discarded the information, please confirm this by
     >sending a note to this address stating that the information
     >you received has been destroyed.
     >If you are not sure whether you should have received certain
     >information or if you have any other questions, please call
     >xxx xxx at (xxx) xxx-xxxx.
     Jeffrey Austen, Tennessee Technological University, Box 5004
     Cookeville Tennessee 38505   U.S.A.  (615) 372-3485

Revenue Canada database allows birthday change

John Howard < >
Thu, 16 Jun 94 23:03:48 PDT
     Something has just come to light that might be of interest to Risks readers
     concerning my end of the year taxes here in Canada. For whatever reason, my
     new accountant (who resides in a different city) filed my tax with a typo on
     it: my birthday was off by one day. Well, as expected, the system the Feds
     have sent me a note saying my birthday had changed from the last time I had
     filed. The form asked me to come down to my local office to correct the error,
     or if this wasn't an error don't worry about it.
     How can they say "don't worry about it"? As far as I know people aren't
     allowed to change their birthday! I chatted with the teller that helped me
     correct the error. He said that his most memorable error was a situation where
     a senior had transposed the middle digits of his year of birth to make him
     younger by decades. The error was caught when the computer found a young
     person claiming pension benefits.
     The teller enlightened me by saying that personal data is taken from only the
     most recent filing. I suppose this would be ok for a change of address or even
     of name, but of birthday! Imagine your favorite ten risks....
     John Howard

NIST Response to Blaze Attack on Clipper

Thu, 16 Jun 1994 17:29:40 -0400 (EDT)
     Note: The following material was released by NIST in response to recent
     articles regarding AT&T/Matt Blaze and the key escrow chip.  A second more
     technical response follows.
     June 2, 1994
     Contact:  Anne Enright Shepherd
     (301) 975-4858
     The draft paper by Matt Blaze* describes several techniques aimed at
     circumventing law enforcement access to key escrowed encryption products based
     on government-developed technologies.
     As Blaze himself points out, these techniques deal only with the
     law-enforcement feature, and in no way reduce the key escrow chips' inherent
     security and data privacy.
          --   "None of the methods given here permit an attacker to
               discover the contents of encrypted traffic or
               compromise the integrity of signed messages.  Nothing
               here affects the strength of the system from the point
               of view of the communicating parties...." p. 7.
     Furthermore, Blaze notes that the techniques he is suggesting are
     of limited use in real-world voice applications.
          --   "28 minutes obviously adds too much latency to the
               setup time for real-time applications such as secure
               telephone calls." p. 7.
          --   "The techniques used to implement them do carry enough
               of a performance penalty, however, to limit their
               usefulness in real-time voice telephony, which is
               perhaps the government's richest source of wiretap-
               based intelligence." p. 8.
     Anyone interested in circumventing law enforcement access would most likely
     choose simpler alternatives (e.g., use other nonescrowed devices, or super
     encryption by a second device).  More difficult and time-consuming efforts,
     like those discussed in the Blaze paper, merit continued government review --
     but they are very unlikely to be employed in actual communications.
     All sound cryptographic designs and products consider trade-offs among design
     complexity, costs, time and risks.  Voluntary key escrow technology is no
     exception.  Government researchers recognized and accepted that the law
     enforcement access feature could be nullified, but only if the user was
     willing to invest substantial time and trouble, as the Blaze report points
     out.  Clearly, the government's basic design objective for key escrow
     technology was met: to provide users with very secure communications that will
     still enable law enforcement agencies to benefit from lawfully authorized
     wiretaps.  It is still the only such technology available today.
     Today, most Americans using telephones, fax machines, and cellular phones have
     minimal privacy protection.  The key escrow technology -- which is available
     on a strictly voluntary basis to the private sector -- will provide the
     security and privacy that Americans want and need.
     *    Statements from "Protocol Failure in the Escrowed Encryption
          Standard," May 20 draft report by Matt Blaze, AT&T Bell
     Note: The following provides additional technical material in response to
     questions regarding a recent paper by Matt Blaze on key escrow encryption.
     Technical Fact Sheet on Blaze Report and Key Escrow Encryption
          Several recent newspaper articles have brought attention to a report
     prepared by Dr. Matthew Blaze, a researcher at AT&T's Bell Labs. These
     articles characterize a particular finding in Blaze's report as a ~flaw~ in
     the U.S. government's key escrow encryption technology. None of the findings
     in Dr. Blaze's paper in any way undermines the security and privacy provided
     by the escrow encryption devices.
          The finding which has received the most publicity could allow a
     non-compliant or ~rogue~ application to send messages to compliant or
     ~non-rogue~ users which will not be accessible by law enforcement officials
     through the escrowed encryption standard field called the Law Enforcement
     Access Field (LEAF).
          Dr. Blaze's approach uses the openly disclosed fact that the LEAF
     contains 16-bit checkword to prevent rogue users from modifying the law
     enforcement access mechanism. This 16-bit checkword is part of the 128-bit
     LEAF, which also includes the enciphered traffic key and the unique chip
          Dr. Blaze's method is to randomly generate different 128-bit LEAFs until
     he gets one that passes the checkword. It will take on average 216, or 65,536
     tries.  This is not a formidable task; it could be done in less than an hour.
     Dr. Blaze questions the adequacy of a 16-bit checkword and suggests using a
     larger one, to ensure that the exhaustion attack would be so time consuming as
     to be impractical.
          The chip designers recognized the strengths and limitations of a 16-bit
     checkword. Following are the reasons why they chose to use a checkword of only
     16 bits:
     * There were four fundamental considerations that the designers considered in
     choosing the LEAF parameters.
     These were:
     (1) ease of access by authorized law enforcement agencies, 
     (2) impact on communications, 
     (3) a sufficiently large identifier field which would not constrain
     manufacturers, and
     (4) the difficulty required to invalidate the LEAF mechanism by techniques
     such as those described by Dr. Blaze.
     * The purpose of the LEAF is to preserve law enforcement's ability to access
     communications in real-time. The encrypted traffic key, which enables them to
     do this, is 80 bits long. In addition to this 80-bit field, the LEAF must
     contain the unique identification number of the key escrow encryption chip
     doing the encryption.
     * The size of the identifier field was the subject of considerable
     deliberation.  In the earliest considerations it was only 25 bits long. The
     chip designers recognized that 25 bits did not offer enough flexibility to
     provide for multiple manufacturers of key escrow devices. Different chip
     manufacturers would need manufacturer identifiers as well as their own chip
     identifiers to ensure that identifiers are unique. Eventually, the designers
     agreed that 32 bits would adequately meet this requirement.
     * In many environments, error-free delivery of data is not guaranteed, and
     there is considerable concern by communication engineers that requiring
     error-free transmission of a fixed field (the LEAF) could make the encryption
     device difficult to use. In early discussions with industry, they were opposed
     to any checkword.  In the end, they agreed it would be acceptable if the size
     of the LEAF was restricted to 128 bits. This left 16 bits for a checkword to
     inhibit bypassing the LEAF. While recognizing the possibility of exhausting
     these 16 bits, the designers concluded that 16 bits are adequate for the first
     intended application. Security enhancements are being made for other
     applications, such as the TESSERA card.
     Note that computations are required to search for a matching checkword, which
     then has to be properly substituted into the communications protocol. The
     performance and cost penalties of the search operation are significant for
     telephone, radio, and other such applications, thus providing adequate
     protection against this technique for bypassing the LEAF.
     In summary:
     * Although this technique would allow one to bypass the LEAF, the security
     provided by the escrow encryption devices would not be altered. Users'
     information would still be protected by the full strength of the encryption
     * Dr. Blaze was accurate in noting that these attacks are of limited
     effectiveness in real-time telephony.
     * When designing the key escrow chip, NSA emphasized sound security and
     privacy, along with user friendliness. The attacks described by Dr. Blaze were
     fully understood at the time of initial chip design. The use of 16 bits for
     the checkword was an appropriate choice in view of the constraints of a
     128-bit LEAF.  It provides excellent security for real-time telephone
     applications with high assurance that law enforcement's interests are
     * Dr. Blaze's research was done using prototype TESSERA cards.  As part of the
     family of planned releases/upgrades, NSA already has incorporated additional
     security safeguards into the production TESSERA cards to protect against the
     kinds of attacks described by Dr. Blaze.

ROLM phones and "Do Not Disturb": how to lose calls

Rob Levandowski < >
Thu, 16 Jun 94 12:26:55 GMT
     Here at the University of Rochester, students are given ROLMphone 120DCMs
     in their rooms. These phones (or, more precisely, the digital switch that
     they are connected to) have a function called "do not disturb". When the
     appropriate code is entered into the keypad, the line is put into DND mode,
     and it -will not ring- for any reason. However, if someone tries to call,
     they hear ringing.
     There are two problems with the implementation of this feature. First, the
     code to activate and de-activate the feature is anything but intuitive. 
     Having lived off-campus for a while, I forget the exact code, but it is along
     the lines of #6x. The code for speed-dialing numbers is #3x. On more than
     one occasion I meant to hit a speed-dial and instead activated do-not-disturb.
     This wouldn't be a big problem... except that there is no indication
     whatsoever that you are in DND mode. No lights, no tones, no message to
     callers. I missed calls for days the first time I did this... and a lot of
     people got concerned because I "was never home".
     This system should at the least have some sort of different dialtone or
     indicator light to show that you won't be getting any calls. (God knows the
     ROLM 120 has enough blinky-lights...) Likewise, since the switch is equipped
     with PhoneMail, it would be nice if it could give an announcement... "The 
     party you have dialed is not accepting calls at this time."
     The privacy may be nice when you're using your dorm room for, shall we say,
     after-hours social research ;) -- but if you're forgetful like me, the
     implementation is pretty troublesome.
     Rob Levandowski, Computer Interest Floor associate / University of Rochester

A320 hull losses: Lies, damned lies and statistics

Pete Mellor <>
Thu, 16 Jun 94 19:45:06 BST
     This thread of the discussion was originally started by Wesley Kaplow
     <> in RISKS DIGEST 16.15 under the title: "Does it matter
     why A3??'s have a poor record?"
     To recap, Wesley said (without citing a source): 
     > Already, Airbus Industry has lost more planes per delivered plane
     > than other major aircraft manufacturer in the past 3 decades (Lockheed,
     > Boeing, MD). 
     I contradicted this in RISKS 16.16, citing a table of statistics from an 
     article entitled ``Der Traum von Total Sicherheit'' ["The Dream of Total 
     Safety"], in the German magazine Focus, 38, 1993, pp18-21, and Wesley has 
     since agreed that his statement requires support (see his follow-up mailings). 
     The table was as follows:- 
     >Aircraft         No. in     Hulls      % Losses 
     >Type             Service    Lost              
     >DC-9/MD-80       2065       68         3.29  
     >Boeing 727       1831       62         3.39  
     >Boeing 737       2515       57         2.27  
     >Boeing 747       988        22         2.23  
     >DC-10            446        21         4.71  
     >Airbus A300/310  636        7          1.10  
     >Airbus A320      411        4          0.97 
     Focus magazine cited "Luftfahrtindustrie" (NOTE: not "Lundfahrtindustrie", 
     as I originally transcribed it) as the source. 
     Since then, I have been jumped on from a great height by several RISKS 
     contributors who have accused me of abusing statistics. Since this is not 
     something I do deliberately, I would like to make the following points 
     (taking into account the various objections raised by those who have 
     written to me):- 
     1. I am well aware that the statistics above are incomplete. They do not 
        allow for the total operating time of each type. They do not distinguish 
        between losses due to on-board system failure and losses due to other 
        causes which could not possibly be blamed on the manufacturer (e.g., 
        the Lockerbie bombing, the Vincennes shoot-down). They do not take  
        account of wear-out and natural retirement, so that the number shown 
        may be the "number sold" and not the "number in service". I quoted them 
        because they were all I had at the time (while being acutely aware of 
        their imperfections). 
     2. Wesley's original statement *is*, however, refuted by these statistics 
        *provided they are correct* (see point 3). A secondary question arises: 
        "Is this a meaningful measure of the safety of a type of aircraft?" 
        I will return to this in point 4. 
     3. Peter Ladkin pointed out to me that the source name that I had originally 
        misread as "Lundfahrtindustrie" and assumed to be some official body 
        which records air accident statistics, is in fact "Luftfahrtindustrie" 
        (well, it was in small print! :-) and means simply "Air Travel Industry". 
        In other words, the source cited by Focus magazine is totally vague, and 
        (as Peter said) about as authoritative as "I read it on the net"! :-) 
        The statistics I naively quoted therefore need substantiation. 
     4. What would convince Joe Public that a given aircraft type was safe to 
        fly? There are several possible measures of the safety of an aircraft 
        design (note: I do *not* pretend that this list is exhaustive):- 
        a) Deaths per passenger mile on the given type. This is used by the 
           aircraft manufacturing industry. Conclusion: air travel is the safest 
           way of going anywhere. 
        b) Deaths per passenger *hour* on the given type. This makes flying 
           about as safe as driving, but the risk would seem to be tolerable, 
           since a probability of 10^-4 per year of dying in a road accident 
           doesn't seem to worry most people (figures based on official UK 
        c) Crashes (i.e., hull write-off) per revenue flight hour. This is used 
           by the certification agencies (FAA, JAA, etc.) when awarding an 
           airworthiness type certificate. The target is a maximum probability 
           of loss of aircraft of 10^-6 per flight hour due to *all* causes. 
           Historically, statistics show that *system-related* causes account for 
           1 in 10. The conservative assumption that there are 100 critical 
           systems on board then leads to the famous 10^-9 requirement for 
           probability of failure of an individual flight-critical system. 
        d) Crashes per cycle (take-off plus landing). 
        e) Crashes per example delivered (which is where we came in! :-) 
        f) Passenger deaths per cycle. 
        g) Serious incidents per flight hour or per cycle. (Q: "How many accidents 
           has the A320 had?"  A: "Five - You forgot about Lille, where an A320 
           landed on top of a Mooney, taking off both its wings and the empennage, 
           and collapsing the A320's front gear. Since nobody was hurt, it doesn't 
           count, or does it?") 
        The whole picture is confused by the fact that the public perception 
        of risk is biased *against* rare events that kill lots of people, and 
        less against common events that kill a few. (In assessing any event that 
        loses the aircraft, you must assume the worst case: that you kill everyone 
        on board. If you crash a car, it's just you and the guy you hit!) 
        I don't pretend to give an answer here, simply raise a few pertinent 
        questions, whose answers (IMHO) are far from obvious. 
     5. A fairer comparison would be between the A320 and competing aircraft 
        *of the same generation*. I would like to thank Robert Dorsett for 
        the following:- 
        757  = 0 in eleven years.
        767  = 1 in twelve years. (Lauda)
        A320 = 4 in five years. (Air France, Indian Airlines, Air Inter, Lufthansa)
     6. Given that all the statistics above are deficient (basically, they lack 
        an exposure time base), they do still tell us *something*. (In considering 
        a fleet above a certain size, we could assume roughly the same operating 
        hours per day for each example, and things like maintenance time, etc., 
        would average out.) We could *tentatively* conclude that the A320 is a 
        long way from being a flying coffin, but also a long way from being the 
        safest aircraft ever, or even as safe as it should be, given its modernity. 
        The public perception of the A320 seems to be that it is the most 
        dangerous thing that ever left the ground. IMHO this is wrong, and we 
        should be careful not to spread false alarm. 
     There are, of course, better statistics (e.g., from Flight International) 
     and I shall attempt to locate a few. The best come from the air insurance 
     industry, but I am not sure that I can get my grubby paws on those for 
     reasons of confidentiality. 
     In the meantime, if anyone knows of a good source ... :-) 
     Also, how can I phrase an argument to convince my mother that I stand a 
     greater chance of being run over crossing St. Johns Road while walking from 
     Farringdon tube station to the University than I do of dying in an air crash? 
     Then I won't have to make long distance 'phone calls from the airport in 
     B*m***k Egypt to tell her we landed safely every time I go to a conference! :-) 
     Peter Mellor, Centre for Software Reliability, City University, Northampton Sq
     London EC1V 0HB  +44 (71) 477-8422 

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