precedence: bulk Subject: Risks Digest 21.28 RISKS-LIST: Risks-Forum Digest Tuesday 20 March 2001 Volume 21 : Issue 28 FORUM ON RISKS TO THE PUBLIC IN COMPUTERS AND RELATED SYSTEMS (comp.risks) ACM Committee on Computers and Public Policy, Peter G. Neumann, moderator ***** See last item for further information, disclaimers, caveats, etc. ***** This issue is archived at and by anonymous ftp at ftp.sri.com, cd risks . Contents: Aasta train crash might have been caused by a safety-critical error (Anton Setzer) Lax security found in IRS electronic filing system (Dave Stringer-Calvert) Dow Jones Industrial Average reported at 0.20 (Lindsay F. Marshall) More on the importance of safeguarding private crypto keys (David Kennedy) Risks of self-induced false alarms (Graystreak) Using automation software without accounting for possible scenarios (Tony Yip) Another "secure" e-book seems unlikely (Moz) The risks of accidentally becoming a customer for life (Jim Youll) NSF study: "Internet Voting is no 'Magic Ballot'" (Terry Carroll) On-line elections (Sarr Blumson) Smart Bombs - Old Story (Bruce E. Wampler) Re: Smart bombs miss again (Richard Schroeppel, Christophe Augier, Pekka Pihlajasaari, Michael Nelson, Bill Stewart, Wm. Randolph Franklin) Abridged info on RISKS (comp.risks) ---------------------------------------------------------------------- Date: Sun, 12 Nov 2000 01:09:06 GMT From: anton setzer Subject: Aasta train crash might have been caused by a safety-critical error [Archive note: overstruck ringed "A" in "Asta" lost in transit. PGN] An extremely detailed report on the Aasta train crash in Norway, 4 Jan 2000, in which 19 people died is now available via http://odin.dep.no/jd/norsk/publ/rapporter/aasta/ Most of it is in Norwegian, but a Summary (pages 275 ff in "12. Sammandrag" at "Del 4") and in the appendices ("Vedlegg") Vedlegg 4 and Vedlegg 5 are very detailed reports on the Signalling installations there in English. To remind you of the accident (which is described in the summary in detail): the accident happened on a single-track line. Two passenger trains, a fast train and a small local train were about to meet. Both left at stations where trains can bypass each other. The fast train had a green signal. The local train was supposed to have a red signal. The trains crashed in between. What was tragic was that both trains were on collision for 4 minutes which was indicated by the train controlling system, but the controllers didn't realize it in time and then didn't have the correct mobile telephone numbers of the trains. Some points I found interesting are: On page 277 of the main report one can read: "In the light of the above, the commission cannot state with certainty what signals were showing on the northbound line at Rudstad station on 4 January 2000. From a technical point of view, it would seem highly likely that a red exit signal was showing. At the same time, the design of the safety system makes the potential for error so great that the commission cannot with certainty exclude malfunction situations that may have produced a different signal aspect." In the report by SINTEF (appendix 4, English version page 53 ff) a long list of known deficiencies is listed. 4 incidents are listed: one in which a signal showed green, although it should have shown red (page 56 ff in the report by SINTEF), one occurring on 18 Apr 2000, after the train accident. 3 of them seem to indicate that under certain circumstances for a short time erroneously a green light is shown. (One incident seem to have been caused by mechanical problems). SINTEF apparently did a by hand analysis of the accident and couldn't find an error. In attachment 5, the report is assessed by Railcert, and SINTEF's report is criticized (section 6.1): "We feel that Sintef's conclusions 2, 4 and 6 suggest that a technical cause, related to the signaling installation, for the accident can be ruled out. We support this conclusion only inasmuch as it applies to a steady state, single cause failure. We do however stress the need to look beyond such "simple causes". "In fact Sintef's studies have revealed a number of deficiencies in the design of NSB87 (and NSI-63) as well as serious hiatus in the collection and safeguarding of possibly vital evidence immediately after the accident. A number of known reports of anomalies in similar installations exist. Based on these, we have been able to construct theoretical scenarios where the behaviour of the signaling installations might at least have contributed to the causes of the accident. These scenarios as well as effects of combinations of several known deficiencies could neither been proven, nor disproved by the evidence in hand, or the result of Sintef's analyses and studies. ******* When looking at the data I found the following interesting: - 3 of the incidents seem to have to do with the fact that the signal system sometimes shows green light for short amount of time although it should show a red signal (one further incident has to do with hanging green light). - It is very strange that the local train which according to the log must have driven over a red light left 3 minutes earlier. - It might be that a train drives over a red light while running. In the situation in question however, the local train was waiting at a station, and when waiting in front of a red light, it is unlikely to drive over it. - The fast train and the local train left at almost the same time: The fast train passes the main exit signal at Rena at 13:06:15. The local train leaves Rudstad platform at 13:06:17 and passes the main exit signal at Rudstad at 13:06:58. From this I conclude that the following scenario might have happened: - When switching to green, under certain circumstances, the signalling system erroneously issues for a short moment a green signal to the opposite signal of the block as well. - The driver of the local train interprets this as an indication that he should drive now in order to bypass the other train in time at the other station. Rudstad. The driver doesn't check the signal again, which probably, when passing the exit signal, already has switched back to red. - If this was the case, this accident is due to a software error. Of course the above is highly speculative and I haven't read the report in detail (especially the Norwegian part). I can imagine as well that the driver of the local train behaved abnormally caused by sleepiness, mental problems, irritation by sun light. I think it would be very interesting to try to find the cause of this accident, in which a software error led to the loss of 19 lives. Anton Setzer, Computer Science, University of Wales Swansea, Swansea SA2 8PP UK http://www-compsci.swan.ac.uk/~csetzer/ +44 1792 205678 ext 4518 ------------------------------ Date: Fri, 16 Mar 2001 07:27:00 -0800 From: Dave Stringer-Calvert Subjects: Lax security found in IRS electronic filing system Even as the IRS was assuring taxpayers last year that electronic filing of tax returns was secure, serious shortcomings existed that could have allowed hackers to view and even change information on returns, a government watchdog agency said. The General Accounting Office found no evidence that hacking had occurred, but it said its investigators were able to gain unauthorized access to the tax agency's electronic filing system, which will handle a third of all federal returns this year. The GAO cited the IRS for lax security controls and for not requiring encryption of electronic returns. The report also said the IRS sent out $2.1 billion in refunds to taxpayers whose returns were not properly authorized. http://www.latimes.com/business/20010315/t000022659.html http://www.msnbc.com/news/TECH_Front.asp http://www.usatoday.com/life/cyber/tech/2001-03-15-e-filing-risks.htm http://www.cnn.com/2001/US/03/08/taxes.electronic.filing/ ------------------------------ Date: Mon, 19 Mar 2001 19:46:37 +0000 (GMT) From: "Lindsay F. Marshall" Subject: Dow Jones Industrial Average reported at 0.20 Oops! Lindsay http://catless.ncl.ac.uk/Lindsay (From DATEK online:) Monday, 19 March 2001, 4:53:47am ---------------------------------- DJIA 0.20 -10031.08 NASDAQ 1890.91 -49.80 S&P 500 1150.53 -23.03 [Source: Article by Kieren McCarthy, 19 Mar 2001, *The Register*: http://www.theregister.co.uk/content/28/17700.html; excerpted by PGN] ------------------------------ Date: Tue, 20 Mar 2001 16:08:59 -0500 From: David Kennedy CISSP Subject: More on the importance of safeguarding private crypto keys Cryptologists from Czech company ICZ detected serious security vulnerability of an international magnitude. http://www.i.cz/en/onas/tisk4.html > A bug has been found in worldwide used security format OpenPGP. The bug > can lead to discovery of user's private keys used in digital signature > systems. OpenPGP format is widely used in many applications used > worldwide, including extremely popular programs like PGP(TM), GNU Privacy > Guard, and others. The bug detection comes on the right time, as Philip > Zimmermann, the creator of PGP program, has left Network Associates, > Inc. and aims to boost OpenPGP format in other products for privacy > security on Internet. From the scientific point of view, the discovery > goes far beyond actual programs - it has wider theoretical and practical > impact. > A slight modification of the private key file followed by capturing a > signed message is enough to break the private key. These tasks can be > performed without knowledge of the user's passphrase. After that, a > special program can be run on any office PC. Based on the captured > message,the program is able to calculate the user's private key in half a > second. The attacker can then sign any messages instead of the attacked > user. Despite of very quick calculation, the program is based on a > special cryptographic know-how. > Similar vulnerabilities can be expected in other asymmetrical > cryptographic systems, including systems based on elliptic curves. DSA and RSA keys are reportedly equally vulnerable. DMK Comment: A detailed report was supposed to be "released shortly" but has not appeared so far. The press release does not specify whether diddling the private key results in any error messages. I hope this does not spawn another round of "PGP is cracked/cracking/crackable" media hysteria. The importance of key management has always been critical and this would seem to only add to the reasons why. There are viruses that try to steal PGP's secret key, there are trojans that make it possible to steal PGP's secret key. Storing keys on shared/networked workstations has always been recognized as a problem with PGP. The comp.security.pgp FAQ includes: Can I put PGP on a multi-user system like a network or a mainframe? David Kennedy CISSP, Director of Research Services, TruSecure Corp. http://www.trusecure.com ------------------------------ Date: Thu, 8 Mar 2001 13:57:54 -0500 From: Graystreak Subject: Risks of self-induced false alarms http://washingtonpost.com/wp-dyn/articles/A38625-2001Mar7.html FBI Director Louis J. Freeh said he and his wife had been baffled by a series of false alarms from the security system in their Great Falls area home. Fairfax County police responded each time, but no suspects had been nabbed. It seems that two of his six sons, then ages 5 and 4, had been amusing themselves by making their 2-year-old brother run in circles in the basement to set off the motion detector. "They would sit and watch for the police to come," Freeh said. [AW notes: no discussion of why the motion detector was on in the basement while the children were home, nor why the police didn't adopt a "call before responding" policy after some number of false alarms.] ------------------------------ Date: Wed, 7 Mar 2001 12:48:36 -0800 From: Tony Yip Subject: Using automation software without accounting for possible scenarios >From www.macfixit.com 7 Mar 2001: Many [Macfixit] readers sent us copies of a letter they received yesterday from the Apple Store apologizing "for the delay in fulfilling" their Mac OS X order. This seemed a bit odd, as Mac OS X won't ship until March 24. So there can be no delay at present. Are they anticipating a delay starting March 24? Or was the message sent in error, probably as the result of some software that automatically triggered the mailing when it detected that the order had not yet been fulfilled? We suspect the latter, as it makes more sense. Consistent with our theory, Evan Chaney writes: " I called the Apple Store and talked to a sales rep who said he thinks this e-mail is invalid and that he thinks it was sent just because the system sends out a backlog e-mail if the product hasn't been shipped after 20 days. Apparently, it doesn't account for pre-ordered products." We have no word from Apple on this as yet. The RISKS: automation is good; but you need to take all scenarios into account; especially when you created the scenario yourself by accepting orders way before the product is due to be shipped. ------------------------------ Date: Mon, 12 Mar 2001 18:28:57 -0700 From: risky@moz.net.nz Subject: Another "secure" e-book seems unlikely I just went through an SSL page to purchase an online book from www.mightybooks.com, with slightly bizarre results. They use the "secure" Acrobat Reader to deliver content, which is a known risk to them (the secure format is anything but). More concerning is their apparent use of a simple counter in their download URL. My URL was of the form: https://shop.mightywords.com/servlet/com.mighty.download. HabitatRequestServlet?saleId=xxxx where xxxx is a small integer. Unfortunately I can't test the surmise that trying the next (or prior) few integers might net me more books, since it requires me to have the 128 bit encryption "upgrade" installed on Windows 2000 (confusingly, their FAQ claims that Service Pack 1 will also fix this problem, but I have that installed). Of more concern is that I could complete the entire sale process on their secure site, only to fail at the actual download stage because that requires a higher level encryption than the rest of the sale. There is no "download a trial document" link on the site (I looked!), so it seems impossible to verify the problem without actually making a purchase (or attempting a theft by plugging numbers into the URL above). Moz ------------------------------ Date: Thu, 15 Mar 2001 08:50:24 -0500 From: Jim Youll Subject: The risks of accidentally becoming a customer for life In 1998 I helped a company computerize its shipping department. While testing documentation and processes, I signed up as a "shipper" in the UPS online system. I neglected to remove myself when the project was finished, and in 2001, I was still receiving promotional UPS e-mail. The messages do not offer an "unsubscribe" hint. So I called UPS. "All you need to do," the rep said, "is to go to 'your page' on the Web site, enter the user ID and password, and clear the correct checkbox" to make the e-mail stop. Unfortunately, I didn't know my user ID and password. UPS insisted it had no way to look up an account name if given an e-mail address. They pointed out that it was really my fault for "forgetting" the user ID I created in 1998 and insisted that "clearing the checkbox" was the only way to make the mail stop. Without a user id, there was "no way to get to the checkbox." After more complaints, they finally contacted the people who run the e-mail database. Turns out I could not possibly have forgotten "the user ID I created in 1998" because in 1998, the system did not employ "user IDs" on accounts -- my records didn't even have one, making them totally inaccessible except to their systems people! Sometime after 1998 the system was changed. UPS says my records are corrected but I don't know if that means I have a "user ID" now, or whether the account was deleted. I wonder about the disposition of the thousands of other early adopters whose accounts lack user IDs. It's still expensive to use version 1.0, even on the Web. ------------------------------ Date: Fri, 16 Mar 2001 14:24:58 -0800 (PST) From: Terry Carroll Subject: NSF study: "Internet Voting is no 'Magic Ballot'" RISKS has previously had discussions of the risks associated with going to computerized voting (especially Internet-based voting) as an attempted panacea for the types of problems we saw in the last US presidential election. The National Science Foundation recently released a study that it commissioned from the Internet Policy Institute on problems associated with Internet voting. The NSF's press release on the study may be found at . The IPI has a page devoted to the study (including a link to the report itself) at . The NSF highlights the following findings with respect to the feasibility of Internet voting: - Poll site Internet voting systems offer some benefits and could be responsibly deployed within the next several election cycles; - The next step beyond poll-site voting would be to deploy kiosk voting terminals in non-traditional public voting sites; - Remote Internet voting systems pose significant risk and should not be used in public elections until substantial technical and social science issues are addressed; and - Internet-based voter registration poses significant risk to the integrity of the voting process, and should not be implemented for the foreseeable future. Terry Carroll, Santa Clara, CA [These results are rather similar to the findings of the California commission. Interested readers should also dig up the recent Caltech/MIT report, which states that lever machines, hand-counted paper ballots, and optically scanned ballots are all significantly more accurate than direct-recording voting machines (DREs) and Internet voting schemes. PGN] ------------------------------ Date: Fri, 16 Mar 2001 11:28:20 -0500 From: "Sarr Blumson" Subject: On line elections The college I attended is running the election for alumni appointed trustee with a Web voting option through election.com. So I went to cast my vote, and got in response: Microsoft OLE DB Provider for SQL Server error '80040e14' The log file for database 'electnet' is full. Back up the transaction log for the database to free up some log space. /dartmouth2001/confirmation.asp, line 92 It's happened twice. It let me vote successfully a few hours later; I'm assuming/hoping it only recorded my vote once. Not I'm imagining trying to explain to the poll watchers in a real election that this message means they should let me vote again. Sarr Blumson, JSTOR, University of Michigan, 301 E Liberty, Ann Arbor, MI 48109-2262 http://www-personal.umich.edu/~sarr/ +1 734 764 0253 ------------------------------ Date: Wed, 07 Mar 2001 14:19:12 -0700 From: "Bruce E. Wampler" Subject: Smart Bombs - Old Story I've been recently been reading "A War to Be Won: Fighting the Second World War" by Murray and Millet (ISBN 0-674-00163-x), and have gotten a bit of perspective on the RISKS of developing high tech weapons that seems to apply to the recent poor performance of the Navy's Joint Standoff Weapon (smart bomb) in Iraq. It seems (CNN: http://www.cnn.com/2001/US/02/26/us.iraq.ap/index.html) that much of the failure was due to not accounting for high winds, and that a software fix that would have the bombs level off longer might make them work. This is just another example of not finding weapon flaws until they are actually used in the field. This is, in fact, a very old story. Just one example from "A War To Be Won": it seems that the United States submarine fleet was very ineffective during the first year or more of the Pacific war because of defective torpedoes. The US subs had the latest, high-tech torpedoes available. Fancy magnetic fuses that didn't work, and a faulty guidance system that didn't work either. Turns out, the Navy engineers had tested the torpedoes without a full weight warhead, and so the sensors that measured the water depth were improperly calibrated. Doesn't this sound familiar? And there are more familiar lessons in the torpedo story. The submarine crews knew the torpedoes didn't work, tried to get the Navy engineers to fix the problem (who denied any problems for a long time) and ended up figuring out how to turn off the magnetic fuses and use a contact fuse (that also had design defects, but worked better anyway), and to field calibrate the depth sensors. I think these very similar stories - 60 years separated - bring up some interesting points. First, using the latest technology is risky in itself, whether it is new magnetic fuses and depth sensors or satellite guided bombs that fail to account for wind. It will remain impossible to really know how the weapons will work until they are really used. It is not an option to start a conflict just to test the weapons! Second, the engineers will always say their weapons are different, and will work. There are no doubt many more lessons, but for now, a final lesson to remember is that there are really not all that many new RISKS around - it so often comes down to the people involved in using and developing the technology - in 1941 or 2001. Bruce E. Wampler, Ph.D., bruce@objectcentral.com ------------------------------ Date: Thu, 15 Mar 2001 14:23:50 -0700 (MST) From: Richard Schroeppel Subject: Re: Smart bombs miss again (Davis, RISKS-21.28) For the last century or so, soldiers have been instructed not to take the time to aim their guns: you do more damage by shooting faster. I don't know what the numbers look like for bombs, but simply knowing "miss/hit" statistics isn't enough information to deprecate the weapon. Rich Schroeppel rcs@cs.arizona.edu ------------------------------ Date: Fri, 16 Mar 2001 12:11:16 -0500 From: "Christophe Augier" Subject: Re: Smart bombs miss again (Davis, RISKS-21.28) "Around 50% of smart bomb didn't functioned in the last NATO bombing." Well, we shouldn't put it this way : 50% of the objectives are still standing. 50% of the enemy facilities, radar, airfields or whatever are still operational. In a "real" war that means retaliation. Usually, that costs a lot more than a entire load of smart-bombs and their F18. The risks are not in the bombs malfunctioning, but in the non-realization of the military objectives. If the ponderated (one target may be more important than another) targets destroyed represent, let's say, 65% of the targets, NATO could be satisfied with this objective. It is all relative. There is another point I wanted to "laser-light" : The cost of the bombing. Technical risk analysis is ok, but you have to deal with financial risks analysis (e.g. in a long war the risk of issuing money to support the war effort. See Germany in WWI and WWII. ...or the risk of losing your next election because of too much tax money spent :). Well, you may multiply the % of awaited destroyed targets (they surely have this kind of statistics for all bombs ; let's say 50% for smart bombs? or it could be calculated with the "circular error probable"*precision of the aim) by the overall costs of the bombing. You will be able to compute the total amount of bombs/money to reach your objectives, and then choose your optimized solution : B52 carpet bombing, smart-bombs, artillery, a mix of them (gulf war), etc. Of course, all this thinking, does not take in consideration "side effects" as civilian casualties, soldiers/pilots casualties, or destroyed embassies. :) On resume: As we don't know the objectives of the last NATO bombing, nor the cost of it, I somehow agree with Randy's answer "In the absence of the relevant numbers and relevant comparison points, the widely repeated "more than 50%" is simply meaningless, no matter how melodramatic it sounds." Christophe ------------------------------ Date: Fri, 16 Mar 2001 07:57:26 +0200 From: Pekka Pihlajasaari Subject: Re: Smart bombs miss again (Davis, RISKS-21.27) The original quotation "most of the bombs ... missed their targets." is semantically quite different from "bombs hit fewer than 50% of the targeted radars." In the original release the military indicated that the majority of their ordnance did not achieve hits. The paraphrasing by Randy changes the semantics to that of a minority of targets did not get hit. It is quite likely that multiple bombs were targeted at a single radar, and no estimate of the actual number of destroyed targets can be inferred from the original press release. This is assuming that the original release was not equally distorted. The RISK is that moving even simple sounding numbers out of context can distort the intent of the statement so much as to make it useless. All the more reason for looking at the source material before drawing a conclusion. Pekka Pihlajasaari Data Abstraction (Pty) Ltd ------------------------------ Date: Fri, 16 Mar 2001 08:46:06 -0600 From: Nelson Michael A CNTR AMC/DOTR Subject: Re: Smart bombs miss again (Davis, RISKS-21.27) Randy Davis used the term "circular error probable" to describe the accuracy of weapons delivery. That phrase is a cryptic, almost opaque variant of the more intuitive, original terminology "circle of equal probability," and can lead to the casual reader asking two pointed questions: * What exactly is "circular error"? * If something called "circular error" does exist, what meaning does the word "probable" add to the concept? This entire semantic discussion becomes moot with the use of the original phrase. It captures the underlying concept noted in Mr. Davis' message in a much more meaningful way: for a given weapon system, the circle where, on average, half of the weapons will land inside the circle and half outside the circle. Unfortunately, "circular error probable" is in widespread use, in both technical and non-technical literature. Michael A. Nelson, Aircrew Force Management Analytical Support ARINC, Inc. ------------------------------ Date: Sat, 17 Mar 2001 12:33:53 -0800 From: Bill Stewart Subject: Re: Smart bombs miss again (Davis, RISKS-21.27) [...] "One target, one smart bomb" would be fun, but it's unlikely. During the First Gulf War, about 97% of the bombs used were still dumb iron bombs. Bill Stewart ------------------------------ Date: 19 Mar 2001 13:10:51 -0500 From: (Wm. Randolph Franklin) Subject: Re: Smart bombs miss again (Davis, RISKS-21.27) I don't think the bombs were even that accurate until the end of WWII. There was a British study around 1942 or so that said that most bombs were more than 5 miles off. IIRC, when Peenemunde was first bombed, the "after" recon photos looked like the "before" photos. This illustrates that accuracy can improve. I have a problem with the argument that something is impossible merely because it's difficult. This seems to be a proxy for the argument about whether we should do it, not whether we can do it. There's the joke that the opponents may be more afraid that it will succeed than that it will fail. Here's an example of how hard problems sometimes get solved. It's not easy to propel a rocket in a straight line by pushing it from the rear. There is a great movie of NACA and NASA rocket mishaps. It has a rocket making a U-turn immediately after launch (apparently a polarity error in the gyroscope wiring), a rocket lifting off a little, then settling back on the pad, a rocket gently tipping over, etc. Now, we've solved all that. Launches are 98% reliable. Perhaps the THAAD is as fundamentally flawed as using a ladder to get to the moon. However, that hasn't been established yet. (Wm. Randolph Franklin) ------------------------------ Date: 12 Feb 2001 (LAST-MODIFIED) From: RISKS-request@csl.sri.com Subject: Abridged info on RISKS (comp.risks) The RISKS Forum is a MODERATED digest. Its Usenet equivalent is comp.risks. => SUBSCRIPTIONS: PLEASE read RISKS as a newsgroup (comp.risks or equivalent) if possible and convenient for you. Alternatively, via majordomo, SEND DIRECT E-MAIL REQUESTS to with one-line, SUBSCRIBE (or UNSUBSCRIBE) which now requires confirmation to majordomo@CSL.sri.com (not to risks-owner) [with option of E-mail address if not the same as FROM: on the same line, which requires PGN's intervention -- to block spamming subscriptions, etc.] or INFO [for unabridged version of RISKS information] .MIL users should contact (Dennis Rears). .UK users should contact . => The INFO file (submissions, default disclaimers, archive sites, copyright policy, PRIVACY digests, etc.) is also obtainable from http://www.CSL.sri.com/risksinfo.html ftp://www.CSL.sri.com/pub/risks.info The full info file will appear now and then in future issues. *** All contributors are assumed to have read the full info file for guidelines. *** => SUBMISSIONS: to risks@CSL.sri.com with meaningful SUBJECT: line. => ARCHIVES are available: ftp://ftp.sri.com/risks or ftp ftp.sri.comlogin anonymous[YourNetAddress]cd risks [volume-summary issues are in risks-*.00] [back volumes have their own subdirectories, e.g., "cd 20" for volume 20] http://catless.ncl.ac.uk/Risks/VL.IS.html [i.e., VoLume, ISsue]. Lindsay Marshall has also added to the Newcastle catless site a palmtop version of the most recent RISKS issue and a WAP version that works for many but not all telephones: http://catless.ncl.ac.uk/w/r http://the.wiretapped.net/security/info/textfiles/risks-digest/ . http://www.planetmirror.com/pub/risks/ ftp://ftp.planetmirror.com/pub/risks/ ==> PGN's comprehensive historical Illustrative Risks summary of one liners: http://www.csl.sri.com/illustrative.html for browsing, http://www.csl.sri.com/illustrative.pdf or .ps for printing ------------------------------ End of RISKS-FORUM Digest 21.28 ************************