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RISKS-LIST: RISKS-FORUM Digest Monday 13 February 1989 Volume 8 : Issue 24

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

Contents: Massive counterfeit ATM card scheme foiled (Rodney Hoffman, PGN) Computer blamed for 911 system crash (Rodney Hoffman) Risks of Selective Service (Rob Elkins) Re: Engines and probabilities (Barry Redmond, Robert Frederking) Re: Structured programming (Jim Frost) Re: Engineering vs. Programming (John Dykstra, Henry Spencer, Robert English, Shawn Stanley)

The RISKS Forum is moderated. Contributions should be relevant, sound, in good taste, objective, coherent, concise, and nonrepetitious. Diversity is welcome. * RISKS MOVES SOON TO csl.sri.com. FTPable ARCHIVES WILL REMAIN ON KL.sri.com. CONTRIBUTIONS to RISKS@CSL.SRI.COM, with relevant, substantive "Subject:" line (otherwise they may be ignored). REQUESTS to RISKS-Request@CSL.SRI.COM. FOR VOL i ISSUE j / ftp KL.sri.com / login anonymous (ANY NONNULL PASSWORD) / get stripe:<risks>risks-i.j ... (OR TRY cd stripe:<risks> / get risks-i.j ... Volume summaries in (i.j)=(1.46),(2.57),(3.92),(4.97),(5.85),(6.95),(7.99).

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Date: 12 Feb 89 14:25:22 PST (Sunday) From: Rodney Hoffman <Hoffman.ElSegundo@Xerox.com> Subject: Massive counterfeit ATM card scheme foiled

Summarized from a 'Los Angeles Times' (11 Feb 89) story by Douglas Frantz:

The U.S. Secret Service foiled a scheme to use more than 7,700 counterfeit ATM cards to obtain cash from Bank of America automated tellers. After a month-long investigation with an informant, five people were arrested and charged with violating federal fraud statutes.

"Seized in the raid were 1,884 completed counterfeit cards, 4,900 partially completed cards, and a machine to encode the cards with BofA account information, including highly secret personal identification numbers for customers."

The alleged mastermind, Mark Koenig, is a computer programmer for Applied Communications, Inc. of Omaha, a subsidiary of USWest. He was temporarily working under contract for a subsidiary of GTE Corp., which handles the company's 286 ATMs at stores in California. Koenig had access to account information for cards used at the GTE ATMs. According to a taped conversation, Koenig said he had transferred the BofA account information to his home computer. He took only BofA information "to make it look like an inside job" at the bank. The encoding machine was from his office.

Koenig and confederates planned to spread out across the country over six days around the President's Day weekend, and withdraw cash. They were to wear disguises because some ATMs have hidden cameras. Three "test" cards had been used successfully, but only a small amount was taken in the tests, according to the Secret Service.

The prosecuting US attorney estimated that losses to the bank would have been between $7 and $14 million. BofA has sent letters to 7,000 customers explaining that they will receive new cards.

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Date: Mon, 13 Feb 1989 13:33:12 PST From: Peter G. Neumann <neumann@csl.sri.com> Subject: Massive counterfeit ATM card scheme foiled

Note that, whether authorized or surreptitious, any access to the card information database -- IDs and PINs -- makes this kind of fraud rather easy. Unfortunately, the remedies are not easy. Even if the PINs were stored encrypted, a preencryption attack (offline) enumerating the 10**6 possible PINs would compromise ALL of the PINs. Thus I conclude that the vulnerabilities here are considerable -- and grossly underestimated. (We have noted before in RISKS that the extent of credit card fraud is actually enormous, although the banks merely pass the losses on to the customers.) PGN

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Date: 12 Feb 89 14:39:12 PST (Sunday) From: Rodney Hoffman <Hoffman.ElSegundo@Xerox.com> Subject: Computer blamed for 911 system crash

Summarized from a 'Los Angeles Times' (12 Feb 89) story by Hector Tobar:

The Los Angeles city emergency 911 telephone system crashed twice Saturday afternoon. Pacific Bell said the shutdown was caused by "a power failure in the computer's signalling mechanism." For four hours, the system was only partly functioning as Pacific Bell engineers worked to repair computers at the dispatch center.

Operators first discovered the phone lines out about 1 pm. Pacific Bell engineers restored parts of the system 5 minutes later, but at 3 pm the system crashed again. A backup system also failed, stopping all emergency calls for 45 minutes. Engineers once again restored the system's phone lines at 3:45. But the system's computers were still not working by late afternoon and the 25 operators at the dispatch center were forced to process calls manually. Computers normally display the address and phone number of the person making the call.

Operators at the center receive about 200 calls per hour. Callers who were unable to get through received a recorded message. Many then called police and fire stations directly. All calls were being answered by late Saturday. A police officer said it was fortunate that the breakdown occurred Saturday afternoon, during a quiet part of the weekend.

The computerized 911 system was installed in Los Angeles in 1983. Located four floors below ground level, it is designed to withstand a major earthquake. "It's a very good system," said a Pacifc Bell spokeswoman.

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Date: 10 Feb 89 17:20:42 GMT From: Rob Elkins <relkins@vax1.acs.udel.edu> Subject: Risks of Selective Service

Recently, a fellow student was sent a letter (computer generated of course) from the U.S. Selective Service System. The letter was a final warning to register in the selective service system before their name was submitted to the Justice Department for felony prosecution. What is ironic about all this is that this person is female and not required to register for Selective Service. Apparently, the computer system that they use maintains a list of female names and assumes that any individual whose name is not on this list must therefore be male. Her full name is Brantley Elizabeth Riley and when she called them to straighten the situation out, they told her that the system doesn't check middle names either. Rob Elkins, University of Delaware

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Date: Fri, 3 Feb 89 09:59 GMT From: "Barry Redmond, Lecturer, Telecoms Dept, KevinSt" <BREDMOND@dit.ie> Subject: Re: Engines and probabilities -- independence

In RISKS-8.17 Craig Smilovitz writes:

>In the discussion about multi-engine aircraft failures, we've seen a lot of > mathematical probability exercises that forget about analyzing the basis > assumption about probability theory. That assumption is the *independence* > of the events in question.

Exactly.

There are many reasons why the probabilities are not independent. Just think about all the factors in common between the engines (2 or 3) on any single plane:

-The engines are the same design -They were manufactured by the same company -They were fitted in the same factory -They were fueled from the same tanker -They were serviced by the same team ...and I'm sure you can all think of others.

If someone makes a mistake on one engine at any of these times, there is a high probability that they will make the same mistake on the other engine(s). The probabilities of failure are not independent because if one engine fails it immediately increases the probability of another failing.

In other words it's another manifestation of the old software debugging rule: "The more bugs you find, the more likely it is that there are more."

Barry Redmond, Dept of Electronics & Communications, Dublin Institute of Technology, Kevin St, Dublin 8 Ireland

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Date: 10 Feb 1989 08:33-MET From: "Robert Frederking" <ref@ztivax.siemens.com> Subject: Re: Engines and Probabilities -- Good math, bad case analysis

There was of course a mistake in my submission on the 2/3 engine controversy. While the P(one or both engines out) I gave was correct for two engines, this isn't the P(crashing), since it can fly on one engine. What I should have used was simply P(both engines out) = p**2, which is indeed smaller than the P(2 or 3 out) for the three engine case.

Robert Frederking, Siemens AG/ZFE F2 INF 23, Otto-Hahn-Ring 6, D-8000 Munich 83 West Germany Phone: (-89) 636 47129

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Date: 12 Feb 89 16:56:02 GMT From: madd@bu-cs.BU.EDU (Jim Frost) Subject: Re: Structured programming

It's possible that this topic has been overkilled, but I'd like to add several recent experiences to the "structured programming" argument.

My company markets a graphical database used for designing and testing event networks, which work much like PERT charts. Since the program is very graphical, it was written for the Silicon Graphics series of machines. Until recently, the SGI machines went for $50,000 or more, somewhat limiting our market. I was hired to port the system to less expensive hardware.

On paper, the design of the system was very good. There were several major portions of code (graphics system, a thing like an interpreter, and a database). Unfortunately, the graphics system was written in a very unstructured format, using many global variables and splitting functions up in odd ways. Instead of being able to make small modifications to work on other graphical systems, a complete rewrite had to be undertaken. After this rewrite, porting to new architectures has taken less than a week per architecture. The newer graphical systems are very, very structured.

Worse than the graphics, the other portions of the system were written by a programmer who must have had job security in mind. They are deliberately obtuse. Portions are very modular while others are so delocalized as to cause me to pound my head against the wall while trying to decipher them (why should a database manager make checks to see if the memory manager is still consistent?). We found that almost all of the modular portions ported with fair ease, while all of the delocalized portions had to be thrown out and rewritten.

What's the net result of giving proper structure to the product? The older system was so unreliable as to force our clients to run it under a debugger (gag). The newer is faster, easy to port, and much MUCH more reliable.

I'd say there's a lesson there.

jim frost, associative design technology madd@bu-it.bu.edu

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Date: Thu, 9 Feb 89 13:43:16 CST From: JohnD@CDCCENTR.BITNET (John Dykstra - CDC Workstation Software) Subject: re: Engineering vs. Programming

I've had the opportunity to be a logic designer on a high-end mainframe development project and an operating systems developer. There's one difference that leaps out at me: Hardware designers get to do the same thing more than once, while software designers, at least in the operating system area, always seem to be cutting new trails through the underbrush.

In these days of software-compatible product lines, it's not uncommon for the same hardware development team to implement an external architecture (the assembly language programmer's view of the machine) several times over the course of a decade. My company has two teams that are each on their third implementation, and you can see progressive improvements in the internal architecture (what the microprogrammer or customer engineer sees). Things get simpler, perform better and are more reliable. Of course, the constraints the team works under change (new LSI gate array technologies, requirements to support more multiprocessing, etc.), but hardware engineers get to learn from their mistakes.

The "building blocks" of hardware design also have not changed very much over time. We're still using registers, adders, control logic, microprogramming stores, etc. Techniques get extended over time, but I expect that you could show a 1950's digital engineer the logic prints for (say) an IBM 3090, and s/he'd be able to follow them easily. I don't think that someone who worked in AutoCoder back in 1960 would be able to read an Ada or LISP program, or even understand some of the basic concepts of the language.

Operating systems seem to take 5 to 10 years from beginning to maturity, so most of us only do one or two in a career. Over a decade, requirements change enough that you can't just re-implement the previous system. For example, in the 60's batch processing was most important, while in the 70's you optimized for timesharing, and in the 80's distributed processing and networking are king. Hardware architectures also change, as support for virtual memory and hardware-support protection schemes is added, and of course we're using much different languages.

Basic design principles don't change, and sometimes they get codified into rulebooks such as "structured programming," and used by people who don't understand the "why" behind them. But the problems I'm trying to solve with my software design work are very different from the ones faced by the guy who occupied this office in 1979. Sometimes I'm thrilled by the challenge of finding my way through this wide-open universe of possible solutions, and sometimes I wish for the safety of designing yet another pipelined arithmetic unit.

I'll bet that the hardware designers on this list believe that they're in a tough situation, and that operating system design is easy! Does anyone want to make a case for that?

John Dykstra - NOS/VE Design - Control Data Corporation (612) 482-2874 JohnD@CDCCentr.BITNET All opinions expressed, etc.

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Date: Fri, 10 Feb 89 00:16:58 -0500 From: attcan!utzoo!henry@uunet.UU.NET Subject: Re: Engineering vs. Programming

>When you design a program, the design and the program can be one and the >same, so a lower level of design documentation is possible.

On the one hand, this is certainly true. I heard the same thing from an EE friend of mine over a decade ago: he preferred software over hardware because changing the software was so much less hassle than updating drawings and such for hardware.

On the other hand, it is not obvious that this automatically means poorer quality. What we have here, actually, is a new version of the classical debate over whether word processing (or the typewriter!) leads to poorer writing. The more powerful tool definitely makes it easier to be sloppy, because less effort and thought is needed to get something out. But it also makes it easier to be perfectionist, because doing multiple iterations to get something absolutely *right* is much less hassle.

I think a fairer statement would be that the shift from hardware to software magnifies differences in how systematic and conscientious people are, and makes it harder for traditional hardware-oriented procedures (and older hardware-oriented managers) to catch the sloppy ones.

Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu

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Date: Thu, 9 Feb 89 10:37:57 pst From: Robert English <renglish%hpda@hp-sde.sde.hp.com> Subject: Engineering vs. Programming

The discussions about software system design have given many reasons for why those systems fail. It seems to me that those reasons can be broken into two main categories--technical and economic--and that any approach that attacks the first without somehow attacking the second as well is doomed to failure.

The immense complexity of software systems makes them difficult to build correctly. A large program can contain well over a hundred thousand lines of code, each of which would represent a moving part in a physical system. No one would expect a physical system that large and complicated to work reliably, at least not without extensive testing and redundancy.

But the technical problems go deeper than that. Physical systems are inherently modular. Each part has well-defined boundaries and performs well-defined tasks. While interactions between parts must be accounted for, these interactions are the exception, rather than the rule. Unless considerable care is taken, the opposite applies to software systems (even with modular software, the objects themselves tend to be more complex and less reliable than physical components).

Computer science has made great progress in addressing these technical issues. The need for documentation is well known, the benefits of proper coding practices have been well publicized, and the risks of buying or selling untested code have been demonstrated time after time. The economic problem remains unaddressed.

Physical systems take time to build. Every new part has to be designed and manufactured. Prototypes have to be built before they can be evaluated. It might take over a year to build a prototype for an automobile, and two or three years to set up an assembly line for a totally new model. Compared to such long product lead times, three or four months of testing are inconsequential. Developers are not, in general, the people doing the testing, so continued development is not seriously affected.

Software systems, on the other hand, take very little time to build. Each change makes its way into the system in the time it takes to recompile and reload. Thus, a software system that takes a year to build will have many times the complexity of a physical system taking the same amount of time, and the corresponding testing period should also be many times as long. In addition, effective software testing usually requires the same level of skill as software production, so that investment in testing adversely affects investment in future development. By greatly reducing the development time for a given function, software has greatly increased the relative cost of making that function reliable.

In a marketplace where time to market is the controlling factor in business success, there is very little an individual programmer, system designer, or company can do to oppose these forces. A company that invests heavily in building reliable systems will lag far behind the market in other measures of system quality, such as functionality and performance, and will find itself limited to those niche markets where reliability is the overriding concern. Only if the marketplace changes so that those niche markets dominate will software reliability improve. --bob--

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Date: Thu, 9 Feb 89 14:37:44 CST From: shawn@pnet51.cts.com (Shawn Stanley) Subject: Re: Engineering vs. Programming

There will probably always be a difference in opinions between engineers and programmers. Although they interact, they are not closely related fields, and thus have totally different problems.

For example, you can't take a test meter and check a program for discontinuity. And you generally don't heat-test a program for industrial use.

There are vast differences in debugging techniques, as well as design techniques.

UUCP: {uunet!rosevax, amdahl!bungia, chinet, killer}!orbit!pnet51!shawn INET: shawn@pnet51.cts.com

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End of RISKS-FORUM Digest 8.24 ************************