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Subject: RISKS DIGEST 11.04 REPLY-TO: risks@csl.sri.com

RISKS-LIST: RISKS-FORUM Digest Thursday 7 February 1991 Volume 11 : Issue 04

FORUM ON RISKS TO THE PUBLIC IN COMPUTERS AND RELATED SYSTEMS ACM Committee on Computers and Public Policy, Peter G. Neumann, moderator

Contents: Subway door accidents (Mark Brader) "Virus" destroys part of Mass. state budget plan (Adam M Gaffin) Reinterpretation of term "Computer Security" (Frank Dixon) SSN and Schwab Telebroker RISKS (Curtis Jackson) Re: Inquiry into cash machine fraud (John Sloan) Re: the new California licenses (Mark Jackson, Mark Gabriele) No more quick n' easy account info from Fidelity (Carol Springs, B.J. Herbison, Carl M. Kadie) Re: Electronic cash completely replacing cash (Lee S. Ridgway) Re: Predicting System Reliability... (Brad L. Knowles, Jeff Johnson) Electronic telephone directory (Jan Talmon) **[A whole issue pending on postage stamp and gas vending machines. GROAN!!!]**

The RISKS Forum is moderated. Contributions should be relevant, sound, in good taste, objective, coherent, concise, and nonrepetitious. Diversity is welcome. CONTRIBUTIONS to RISKS@CSL.SRI.COM, with relevant, substantive "Subject:" line. Others ignored! REQUESTS to RISKS-Request@CSL.SRI.COM. FTP VOL i ISSUE j: ftp CRVAX.sri.com<CR>login anonymous<CR>AnyNonNullPW<CR> CD RISKS:<CR>GET RISKS-i.j<CR> (where i=1 to 11, j is always TWO digits. Vol i summaries in j=00; "dir risks-*.*<CR>" gives directory; "bye" logs out. ALL CONTRIBUTIONS CONSIDERED AS PERSONAL COMMENTS; USUAL DISCLAIMERS APPLY. Relevant contributions may appear in the RISKS section of regular issues of ACM SIGSOFT's SOFTWARE ENGINEERING NOTES, unless you state otherwise.

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Date: Thu, 7 Feb 1991 14:07:00 -0500 From: msb@sq.com (Mark Brader) Subject: subway door accidents (Pete Mellor, RISKS-11.03)

Here in Toronto, the subway staff can open one door on each side of each car, but they need a key to do so. There is an interlock so that any door open more than 1-2 cm prevents acceleration from being applied, and opening the door with the staff key apparently does not override the interlock. (At least, the usual indicator lights do come on.) All of this is exactly the way I would expect sensibly run systems everywhere to do it. So let's hear about the counterexamples...

It *is* possible for a train to run with a door open, in case the door fails; to do so requires the operation of an override control concealed under the passenger seats. In that case the door-open warnings do not light. On using the override, the crew place large "Danger - Do Not Use" banners across the doorway. This too seems entirely sensible.

The open-door interlock is not sufficient to prevent accidents of the type described above. The closing doors can trap things like a coat sleeve or a trailing purse, and people don't always react properly. There was a fatal accident here last year which may have been of this type (the exact cause was not proved); it resulted in a long inquest and a lot of unfavorable publicity for the transit system; and as a result of this, we now have what seem to me to be annoyingly paternalistic advertisements, basically telling us that it's always better to wait for the next train than to try to catch one that's just leaving.

The operating practice here is to start the train the instant all doors are closed -- often the driver sets the control to accelerate as they start closing, and lets the interlock start the train when they finish. On a past visit to New York, on the other hand, I noticed that there they wait a couple of seconds after closing the doors and before starting the train. And as I recall London does the same. I then read about an accident in New York where someone had tried to force the doors open during those seconds, and gotten caught and killed. My conclusions were that New York does not have a door/power interlock (though I suppose it might be that the fool merely managed to not trigger it) and that it is actually safer to start away at once because it reduces the temptation to those who would try this sort of thing.

Mark Brader SoftQuad Inc., Toronto utzoo!sq!msb, msb@sq.com

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Date: Thu, 7 Feb 1991 17:36:00 GMT From: adamg@world.std.com (Adam M Gaffin) Subject: "Virus" destroys part of Mass. state budget plan

Reason 4,012 to back up documents: A case study

Middlesex News, Framingham, Mass, 2/7/91

By Adam Gaffin NEWS STAFF WRITER BOSTON - State officials say a computer virus destroyed 50 pages of Gov. Weld's budget proposal earlier this week, but a computer consultant with experience in fighting the bugssays uit sounds more like a case of inadequate maintenance than anything sinister. Michael Sentance of Maynard, a legislative aide to Weld, had typed in 50 pages of the governor's proposed budget on a Macintosh computer when he tried saving the document to the machine's hard drive around 3 a.m. on Monday - only a few hours before it was due to be submitted to the Legislature. But instead of being saved, the document disappeared, according to Liz Lattimore, a Weld spokeswoman. Sentance was eventually able to retrieve an earlier draft, filed under a different name, minus the 50 pages, she said. Because of the snafu, Weld was forced to delay submitting the plan by a day. When Sentance ran a program to check for the presence of viruses on the machine, it responded with a message indicating a ``type 003 TOPS network'' virus, Lattimore said. TOPS is the name of the network used by the Executive Office of Administration and Finance to connect its Macintoshes. Sentance had borrowed one of that office's computers because he was more familiar with Macs than with the older Wang system in the governor's suite, Lattimore said. Viruses are small programs that can take control of a computer's operating system and destroy other programs and data, and can be spread through people unwittingly sharing ``infected'' programs or disks. Lattimore said officials managed to transfer data from the ailing computer to another machine, adding that they are now checking all of Administration and Finance's Macintosh computers for possible infection. But Eileen Hoffman of Needham, a Macintosh consultant, says what happened to Sentance sounds more like a hard-drive ``crash'' than a virus - something she said is potentially far more destructive. A document that disappears when the user tries to save it onto the hard drive usually means there is something physically wrong with the computer's hard drive, not that it is under viral attack, Hoffman said. Hoffman, who keeps three or four infected disks in a safe so that she can test new anti-viral software, said the software that runs TOPS networks is written in such a way that it can show up as a ``virus'' in programs that check for viruses. She said a ``Type 003'' virus is one of these phantom ``sneak'' viruses. Hoffman said Macintosh users are often more lax about maintaining their computer's hard drives than users of IBM compatible machines, because Macintoshes are aimed at people who do not want to have anything to do with the hardware of their machines. The Macintoshes were installed during the Dukakis administration. But even Mac hard drives require regular maintenance, she said. She said she often gets calls from clients who blame disappearing data or strange things on their screens on viruses, but that almost always the problem is caused by a mechanical hard-drive problem. She added that the particular version of anti-viral software Sentance used is two years out of date. Since new viruses are created all the time, this means the software might not be able to detect one even if the machine were infected, she said.

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Date: Wed Feb 6 09:01:17 1991 From: fhi0011@hq.dla.mil (Frank Dixon, fdixon@hq.dla.mil) Subject: Reinterpretation of term "Computer Security"

One of the moguls in our business has publically taken the position that computer security, as a concern, should be interpreted to include _all_ data not just data perceived to be "at risk." He suggests--at his most extreme pole--that the term "sensitive data" should be stricken from the lexicon of security practitioners.

Given that those charged with protected the information judged to be sensitive are more or less plowing an uphill furrow, I am concerned that this movement toward a broadening of the coverage of the concern will have either of two deleterious effects: (1) It may weaken the already feeble attempts to protect the truly sensitive, or (2) be used pragmatically as a justification for "protecting" all communications.

I don't like the implications.

Frank Dixon, Alexandria, VA

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Date: 7 Feb 91 20:46:02 GMT From: !jackson@adobe.UUCP (Curtis Jackson) Subject: SSN and Schwab Telebroker RISKS

This morning my girlfriend decided to sell some stock in her Charles Schwab (a popular U.S. discount stock brokerage firm) account. Schwab has a 24-hour automated telephone quote and order service called Telebroker, and since I know that stock orders placed through Telebroker qualify for a 10% discount on commission fees, I suggested she place her order over the telephone with the automated system.

All of her records (including her account number) were at work, but she glibly called up the local Schwab office and was able to obtain her account number simply by giving her social security number and her address. She then called up Telebroker for the first time ever, entered her account number, and it asked for *the last four digits of her social security number as her default password*. "This is easy," she said. And indeed it is! It then had her pick a new password, and dropped her into the standard interface. I do not know if it would have balked if the "new" password she entered was the old one -- the last four digits of her SSN.

Telebroker is a relatively new and somewhat unknown feature offered by Charles Schwab. As easy as it is to obtain social security numbers of people in the U.S., it would be very easy to find someone who has a Schwab account but has never used Telebroker. If you couldn't get their Schwab account number on your own, you could simply call up Schwab and get their account number, then call Telebroker and have a good deal of fun at their expense. Certainly you couldn't get your hands on the proceeds from a stock sale, but if you wanted to wreak havoc on their life you could sell valuable stocks they are holding, or find a climbing stock and margin them into it to the hilt. Schwab allows you to purchase 1.5 times your equity on margin. Schwab further has a [somewhat lax] policy of not leaving completed transaction confirmation messages on answering machines for privacy reasons, so if you do it while Mr. X is out of town he won't find out what you've done until the margin call.

Even without the human-induced risk of giving out account numbers on the telephone, the risk of using the last four digits of the SSN as the default password is a great one.

Curtis Jackson @ Adobe Systems in Mountain View, CA (415-962-4905) Internet: jackson@adobe.com uucp: ...!{apple|decwrl|sun}!adobe!jackson

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Date: Thu, 7 Feb 91 12:21:35 MST From: jsloan@niwot.scd.ucar.EDU (John Sloan) Subject: Re: Inquiry into cash machine fraud (RISKS-11.03)

> A bank engineer is being interviewed by police investigating unauthorized >withdrawals from cash machines. It is alleged that money was withdrawn from >customers' accounts through information gained during the servicing of machines >operated by Clydesdale Bank.

This reminds me of a personal anecdote that illustrates how computers can play passive partners in "low-tech" cash machine ripoffs. In 1975 I worked for a national bank which was among the first to introduce cash machines to the region. Normally the cash machines were online and continuously monitored by a DEC PDP-11 front-ending an IBM 370/135 (I should mention that the cash machines were not manufactured by either of these two firms). The machines had offline capabilities in the case that the host systems went down and thus an account could not be verified.

One weekend we were converting from a 370/135 to a 370/145 during which time there was a short period in which the machines were left in offline mode. While the machines were acting independently a large theft occurred from the cash cassettes of several machines. There was no record of transactions on the internal audit paper tape on any of the victimized machines. It was clearly an inside job, since the thief knew precisely when the host system would be unavailable.

Since I was on duty that weekend during the conversion I was among the personnel interviewed by the FBI. Nearly a year later, after changing jobs, I read where the FBI had arrested one of two of the cash machine vendor's service people, who had confessed. His crime involved some special knowledge -- if a cash machine were to be opened while online that would be time stamped on the host system console -- but required no more technology than the key to open the vault in the rear of the machine.

John Sloan, NCAR/SCD, POB 3000, Boulder CO 80307 +1 303 497 1243 jsloan@ncar.ucar.edu ...!ncar!jsloan jsloan%ncar@ncario.BITNET

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Date: Wed, 6 Feb 1991 14:33:00 PST Sender: Mark_Jackson.wbst147@xerox.com From: mjackson.wbst147@xerox.com Subject: Re: the new California licenses

That's "coercivity" rather than "corrosivity"; it's a measure of how "stiff" the system is in the sense of resisting changes in magnetization. (Differences in coercivity between DD and HD diskettes in both 3 1/2 and 5 1/4" formats have a lot to do with the inadvisability / impossibility of using DD disks at the higher densities.)

The oersted is the unit of magnetic field strength in the CGS system.

Mark <MJackson.Wbst147@Xerox.COM>

[Also noted by Fred Gilham <gilham@csl.sri.com>, Steve Bellovin <smb@ulysses.att.com>, Ron Fox <fox@rudolf.nscl.msu.edu>, and Mark Gabriele (gabriele@hub.toronto.edu). Even PGN noticed it, but did not get around to fixing it. I try, but I do not always fix everything that needs it. If I did, I would probably be Chorusively Orst(ed) on my own Peterd. PGN]

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Date: Thu, 7 Feb 91 11:13:43 EST From: gabriele@riverdale.toronto.edu (Mark Gabriele) Subject: Re: the new California licenses

>... The other two tracks will be in a format that is incompatible >with current commercial readers, and will contain the rest of the >information that is printed on the front: birth date, eye color, hair >color, height, weight etc.

The author then goes on to point out the issues of loss of privacy from this new system, and how all shopkeepers will soon inevitably upgrade their card readers to capture this important and private information.

I don't see what the privacy problem is here, provided that the only data which is encoded magnetically on the back of the cards is currently available in human-readable format on the front of the card. If you'll give your driver's license to a clerk, you should be prepared to have the clerk copy down all of the information on that license (I've had clerks meticulously copy my height, weight, and eye color off of the driver's license while I and the customers behind me waited).

=Mark Gabriele (gabriele@hub.toronto.edu)

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Date: Wed, 6 Feb 91 13:18:42 EDT From: Carol Springs <carols@drilex.dri.mgh.com> Subject: No more quick n' easy account info from Fidelity

In today's Boston Herald (Febrary 6), Robert Powell has a followup to his article on Fidelity that appeared yesterday. Basically, Fidelity has "slammed the door shut" on Fidelity Telephone Connection. Tracey Gordon at Fidelity says, "We changed it in response to concerns by some of our shareholders who called because of reports in the press."

People who called the toll-free number on February 5 got a real human person asking for SSN and Fidelity account number.

According to Gordon, a system is being set up wherein callers will enter their account number along with their SSN. And a few weeks later, a PIN system will be put into place.

Carol Springs carols@drilex.dri.mgh.com

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Date: Thu, 7 Feb 91 07:46:47 PST From: "B.J. 07-Feb-1991 1021" <herbison@ultra.enet.dec.com> Subject: Discontinued: Quick n' easy access to Fidelity account info

In a message in RISKS-11.03, Carol Springs described a system that allowed access to Fidelity Investments account information using an 800 number and a social security number. The message said it was possible to call Fidelity and request blocking for your accounts. When I called Fidelity and asked about the service, the response was:

`No, we discontinued that service.'

I thanked the representative, told her I was pleased that the service was dead, and hung up. A small victory for privacy.

On a related note, when you call 1-800-DISCOVER you are given the opportunity to check your Discover credit balance automatically. When this service first started, only the card number was needed. Because of complaints, the system now require your zip code as well. Another reason to refuse to write your address on your credit card receipt.

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Date: Thu, 7 Feb 91 11:27:52 -0600 From: "Carl M. Kadie" <kadie@cs.uiuc.edu> Subject: Quick n' easy access to Fidelity account info

I just called Fidelity. The representative say that the Telepeople system has been taken down until they can add PIN protection.

[O PIN, O SESAME? PGN]

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Date: Thu, 07 Feb 91 10:46:55 EST From: "Lee S. Ridgway" <RIDGWAY@mitvma.mit.edu> Subject: Re: Electronic cash completely replacing cash

No one seems to have proposed the most obvious, simple solution to the risks of americards and mastercards: cash! I find that for my normal purchasing habits, I can pay cash. I can go to my bank machine two or three times a week [I know some people who visit theirs daily!], get cash to cover known purchases for several days, and not have to bother waiting for clerks to fill out charge slips, get verifications, and other time-consuming procedures. Thus, I pay for groceries, gas, meals, recordings, books, concerts, etc., etc.

I do have credit cards, but I use them only for large or very specific purchases. That means few databases have records of my purchasing habits. I also don't carry balances, or incur interest, and don't have to write several big checks to credit card companies each month.

For those who are now going to say that cards are safer: I live in a city where street robbery is not unknown, but I don't carry very much cash at one time - and I don't carry my cards unless I know I will use them. Yes, I've been robbed a few times (in about 20 years), but never lost much cash, and lost much more in time and aggravation over stolen credit and ID cards than the cash.

For those who say cards are more convenient: Carry more than two, and they are as bulky as bills. They require more time to complete a transaction (compare the time it takes to pay a restaurant bill in cash vs. credit card!). Compare the amount of time needed for a verification, especially if the phone or computer connection is down or slow, or the manager is not around. Compare the amount of time needed once a month to sit down and check store receipts against bills, write checks, etc.

One other possible blessing of cash and not cards: I find that I am on the mailing list of only one or two mail-order houses, from whom I receive catalogs maybe once a month, while my housemate, who uses credit cards for just about everything, receives at least six or more catalogs per day! Cause and effect?

[NO MORE RESPONSES on this topic for a while. We are badly backlogged. PGN]

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Date: Wed, 6 Feb 91 19:16:41 EST From: blknowle@frodo.jdssc.dca.mil (Brad L. Knowles) Subject: Re: Re: Predicting System Reliability...

In reference to Richard P. Taylor's point in 11.03, namely that to show "sufficient" reliability for a system requires that the entire system in question run in a production environment for longer than the required time, I must agree. In fact, with the things about quality that we are learning from the Japanese (who learned it from Dr. Deming), I would claim that the entire system in question run in a production environment for a six-sigma period of time.

For those of you who might not have been accustomed to the term six-sigma, I will attempt my best explanation (poor 'tho it will be):

In statistics, we can call sigma the Standard Deviation of the Probability of Failure of the system in question. The term x-bar (a lower- case x with a bar above it) is the Mean Probability of Failure of the system in question. X-bar plus six-sigma is the value we want to prove is lower than some given criterion, to a certain level of confidence.

We then compose what is called a "Null Hypothesis" that is the exact opposite of what we are trying to prove (namely, that our system will last at least x amount of time). We then try to prove our Null Hypothesis wrong, to a probability of 95% or better. If we prove to 95%, then we have proven to a two-sigma level of confidence that are system will last at least as long as desired. If we prove to a 99%, then we have proven to a three-sigma level of confidence. If we prove to a 99.997%, then we say we have a six-sigma level of confidence. The test used to show the level of confidence is usually "Student's T Test", for historical reasons (I know, there are oodles of other tests, this just happens to be the first taught in most University Senior-level Stat courses, and probably the best known).

One thing to keep in mind, as we get to higher levels of confidence, we must test our system for exponentially long periods of time, assuming that all else is equal (which, we all know, never happens). That is, unless you test hundreds or even thousands of units, all in parallel. This is how a disk drive manufacturer can say something like "50,000 Hours Mean Time Between Failures" -- you didn't think they actually had a single drive that they tested for 50K+ hours, did you? I would go so far as to say that no well known drive manufacturer today has a single drive with 50K hours on it -- they'll get junked and replaced long before that happens. Still, the drives fail.

The exact numbers of units that you would have to test to prove a certain level of confidence can also be calculated by well known statistical methods, so that you might have to test only 53 units to get the level of confidence desired.

Basically, this is what the Japanese are hitting us over the head with. Most Japanese companies have been using six-sigma Statistical Quality Control for years now, and many of the front runners are now going to nine-sigma (and even twelve-sigma)!

Now, the problem we've got is when we try to test a system like a Nuclear Power plant. We certainly can't afford to build a single plant to try to prove our system will last at least x number of years without failure, much less build *MULTIPLE* identical plants to do so. Thus, all we can really do is unit-test as many parts as we can, and forgo the system testing. I can point out to one very well known system where this has led to many heartaches, if not outright system failure before it was ever put on line -- the Hubble Space Telescope. Everything was completely unit-tested, but system testing was deemed too expensive and time-consuming. Still, in some cases, system testing just is not possible.

Oh well, this is an interesting discussion of an ages-old problem -- it is non-trivial to prove even trivial systems correct (or when they will fail), not to mention how hard it is to prove non-trivial systems correct!

Brad Knowles, Sun System Administrator, DCA/JDSSC/JNSL, The Pentagon BE685, Washington, D.C. 20301-7010 (703) 693-5849 | Autovon: 223-5849

Disclaimer: Nothing I have done or said in the above should be construed as an official position or policy of the Defense Communications Agency or the United States federal government. The author is the sole person responsible for the content of this message.

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Date: Thu, 07 Feb 91 10:32:49 PST From: Jeff Johnson <jjohnson@hpljaj.hpl.hp.com> Subject: Re: Predicting system reliability (RISKS 11.02)

This discussion is muddied by a failure to distinguish between reliability and functional sufficiency. I believe that there is a tradeoff in systems engineering between reliability and sufficiency. If a problem exists that is to be solved by a system, the system designers are often faced with the choice of designing a system that solves the problem or one that is reliable and maintainable. The reliable design usually solves some sub-problem.

Many system designers don't realize that they are faced with this tradeoff: they design a system to solve the full problem and only after it is built do they discover that it is so complex and bug-ridden that it cannot be relied upon or maintained. Or, perhaps seeing the tradeoff, perhaps not, they aim low and deliver a reliable, maintainable system that doesn't do what was desired. Either way, the resulting system doesn't solve the customer's problem.

Often, as a system designer, I've had programmers respond to design specifications by saying: "Providing functional capability X would require me to write a non-modular program. I won't make it non-modular, so you can't have feature X." This argument is of course false -- any thing that can be done "non-modularly" can also be done "modularly" -- but it illustrates the programmer's tendency to sacrifice functional sufficiency for reliability and maintainability. Customers, salespeople, and those who write functional specifications typically exhibit the opposite tendency: requesting or promising functionality that would exceed developers' ability to produce a reliable system.

An example from SDI: Initially, the plan was to design a system in which there was a great deal of inter-component communication in order to coordinate the defense. Critics correctly shot down this plan as hopelessly unreliable. The SDIO responded by advocating a decentralized design involving significantly less inter-component communication. Under further criticism, control was further decentralized until we ended up with "Brilliant Pebbles", in which at least the "business-end" components are supposedly autonomous, and which managed to win over a few SDI critics.

My reaction to Brilliant Pebbles and some of the other decentralized plans that preceded it was that even if they are more reliable than centralized designs (and this is debatable), they wouldn't solve the problem from a functional point of view: massive inter-component communication may well be *necessary* for the system to accomplish its task. Unfortunately, massive inter-component communication also implies a level of unreliablility that, for SDI, is unacceptable.

If handed a functional specification for SDI, I could write a ten-line C/unix program that would be (I assert) highly reliable. But it wouldn't meet the functional specification. Some SDI proposals (and some proposals for other ambitious projects) are simply schemes to develop slightly-larger "ten-line" programs that won't do the job.

Computer Science has partially addressed the issue of reliability and maintainability by developing: 1) formalisms for proving correctness of programs, 2) programming languages and tools providing more support for program correctness (e.g., modularity, strong-typing), 3) improved methodologies for software engineering. These don't insure reliable systems, but they help. Has Computer Science developed anything analogous for analyzing functional sufficiency of programs (beyond a few proofs that certain extremely ambitious functional specifications can't be met)? Might such an analysis be useful here?

JJ, HP Labs

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Date: Wed, 6 Feb 91 22:19 N From: <MFMISTAL@HMARL5.BITNET> Subject: Electronic telephone directory

In the Netherlands, printed telephone directories provide telephone numbers by using the name as an index. Currently, there is also an electronic version of those directories available by means of a VIDITEL service. Here it is also possible to ask for a telephone number by providing the street name, the house number and the city. This involves an inherent risk. When one observes that there are apparently no people in a house, one can ask for the phone number, dial that number and when no one replies.... it may be safe for burglars to go in. It seems also to be an invasion of one's privacy, since one need not to know a name in order to place haressing/obscene phone calls.

The only thing one needs is a PC and a modem. The costs: 35 cents (20 ) a minute.

Jan Talmon, Dept of Medical Informatics, University of Limburg, Maastricht, The Netherlands

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End of RISKS-FORUM Digest 11.04 ************************