The Risks Digest

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 26 Issue 26

Weds 29 December 2010

Contents

Radiation Machines Overdosing Again
Peter Bernard Ladkin
How medical radiation mistakes happened
Jeremy Epstein
UAVs needed encryption
John Long
FCC Acts to Preserve Internet Freedom and Openness
Monty Solomon
Technolog - Hackers steal Walgreens e-mail list, attack consumers
Monty Solomon
Risks of incomplete online archives
Thomas Wicklund
Cell phone "emergency mode" *preventing* 911 call
Joe Thompson
China's MIIT Declares Most VOIP Services, Including Skype, Illegal
Lauren Weinstein
Google Maps vs. USPS in Wisconsin
Richard S. Russell
Gadgets Bring New Opportunities for Hackers
Matthew Kruk
Risk Assessment and Failure Analysis ...
Rob Slade
Info on RISKS (comp.risks)

Radiation Machines Overdosing Again

Peter Bernard Ladkin <ladkin@rvs.uni-bielefeld.de>
Wed, 29 Dec 2010 08:06:25 +0100

There is an article in *The NYT* today (29 Dec 2010) about machines made by
Varian Medical Systems, which deliver so-called stereotactic radiosurgery,
SRS.

Patients have been overdosed. The article says that “according to records
and interviews, the SRS unit at Evanston lacked certain safety features,
including those that might have prevented radiation from leaking outside the
cone.''  Some cases have been put down to `operator error': “In Missouri,
for example, 76 patients were overradiated because a medical physicist did
not realize that the smaller radiation beam used in radiosurgery had to be
calibrated differently than the larger beam used for more traditional
radiation therapy.''

The article is available to registered users of the NYT WWW site at
http://www.nytimes.com/2010/12/29/health/29radiation.html

We are talking 17 years since the 1993 Leveson-Turner article on the
Therac. Despite (we will surely hear) `measures' having been `put in place'
to prevent such a thing from happening again, it appears to be the same-old
same-old. As are the excuses:

  Medical physicists say there is nothing inherently wrong with linear
  accelerators that deliver general radiation therapy, as well as SRS. And,
  they say, the overdoses might have been caught had users followed a more
  rigorous system of checks and double-checks.  “Tens of thousands of
  patients have been treated with protocols properly followed and no
  mistakes were made,'' said Dr. Frank J. Bova, a medical physicist in
  Gainesville, Fla., and a pioneer in developing and enhancing the accuracy
  of SRS.  “It has changed many difficult procedures, ones with high
  surgical risk, into one-day outpatient procedures.''

I wonder. Do we see airline executives on the TV after a major aircraft
accident saying "it's only one plane; there are hundreds/thousands of others
just like this one flying every day without problems!"? Or Toyota: "it's
only one (or a few cars) with bad floormats! There are thousands/millions of
cars just like this driving every day without problems!"

What is there about medical accidents which lets everyone be comparatively
so complacent about them compared with other walks of life such as
transportation?

Isn't there are Hippocratic oath to the effect of "do no harm"? What is this
except doing harm? Is it because the devices are operated by technicians who
have not taken the oath, rather than doctors who have?

Isn't it about time that professional engineering bodies took a public stand
that such events are avoidable and should be avoided? That devices prone to
accidents through "operator error" should be taken off the market and
redesigned? To adopt the de facto standard set by the aviation industry,
that some set party is deemed liable (in aviation: the airline) and pays
compensation? (Obvious candidates here would be the manufacturer or the
hospital; one would then leave it to the insurance industry to negotiate
contributory payments from other parties, as insurance usually does.)

There are three general international standards governing the development of
safety-related systems involving programmable electronic components (and we
may be sure these machines have programmable electronic components). IEC
61508, and its derivatives (so far I know of an international standard for
the process industries, a set of European standards for railway systems, and
a draft international standard for automobiles), DO178B for aviation, and a
separate set of standards, IEC 60601 series, for medical devices. I don't
know 60601, but I suspect there is something seriously wrong with the way
this whole domain is working if, two decades after Therac, laws still allow
safety-critical devices prone to avoidable "operator error" to be used
pervasively.

Peter Bernard Ladkin, Causalis Limited and University of Bielefeld
www.causalis.com  www.rvs.uni-bielefeld.de


How medical radiation mistakes happened

Jeremy Epstein <jeremy.j.epstein@gmail.com>
Wed, 29 Dec 2010 10:14:27 -0500

Another case where patients were given incorrect (and harmful) doses of
radiation, this time because a linear accelerator device had been outfitted
with a "cone" to direct radiation, but the design was such that radiation
could leak around the edges.  *The NY Times* reports that Dr. Howard I.
Amols, chief of clinical physics at Memorial Sloan-Kettering Cancer Center
in New York, said some problems appeared to be “a combination of user
error, coupled with neither the manufacturers nor the FDA being able to
anticipate a potential safety flaw in a `mix and match' treatment delivery
system.''

The problem is with a system made by Varian, and involves using three
computers: "a treatment plan is developed on one computer, then transferred
into another software system that, among other things, verifies that the
treatment plan matches the doctor's prescription.  The data is then sent to
a third computer that controls the linear accelerator."  There are also
compatibility problems - Varian warned its customers that the "software did
not recognize cone attachments on the type of linear accelerator involved in
the Evanston accidents....  To work around that problem hospitals needed to,
as one medical physicist put it, essentially trick the machine into thinking
it was using a different attachment, which it did recognize. To do that,
users had to enter additional data into the SRS system. ... Last year,
Varian promised to devise, among other things, a decidedly low-tech
solution: a decal to stick on the machines, warning operators to be extra
careful in setting the radiation field."

It appears that part of the problem is that there are two different
regulatory regimes - if the machine uses radioactive isotopes it goes
through the Nuclear Regulatory Commission, but if it uses a linear
accelerator to create the radiation (like the Varian system in this case),
the weaker Food and Drug Administration.

The RISKS are old - cobbled together systems, or systems with
repurposed pieces, are more likely to have mismatches that lead to
safety failures, just as we saw with the Therac-25 over 25 years ago.
I suspect (although the article does not hint at this) that the
continuing pressure to increase usage of expensive machines leaves
less time for the medical physicists to learn the machines thoroughly
and verify the settings precisely.

See also RISKS-24.47, 25.82, 25.92, 25.93, 26.02, and many others....
dating back to 3.09.

http://www.nytimes.com/2010/12/29/health/29radiation.html?_r=1&hp


UAVs needed encryption

John Long <j1long@mindspring.com>
Tue, 21 Dec 2010 09:58:38 -0500

It turns out that communication between ground controllers and UAVs was
unencrypted for quite some time.  According to the article below, the
communication could easily be intercepted using a $26 piece of equipment,
which some had been taking advantage.  We just began encrypting that
communication about a year ago.

The risk here is not taking inexpensive precautions against a flaw you are
aware of, and assuming your opponent is not sophisticated enough to exploit
that flaw.

http://www.strategypage.com/htmw/htiw/articles/20101201.aspx


FCC Acts to Preserve Internet Freedom and Openness

Monty Solomon <monty@roscom.com>
Tue, 21 Dec 2010 18:01:16 -0500

December 21, 2010

FCC Acts to Preserve Internet Freedom and Openness.

Action Helps Ensure Robust Internet for Consumers, Innovation, Investment,
Economic Prosperity

Washington, D.C. - The Federal Communications Commission today acted to
preserve the Internet as an open network enabling consumer choice, freedom
of expression, user control, competition and the freedom to innovate. ...

http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-303746.pdf

Genachowski Statement
http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-303746A1.pdf

Copps Statement
http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-303746A2.pdf

McDowell Statement
http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-303746A3.pdf

Clyburn Statement
http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-303746A4.pdf

Baker Statement
http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-303746A5.pdf

  [Interesting.  The two Democrats are complaining that Genachowski did not
  go far enough, particularly toward wireless network neutrality, and the
  two Republicans are complaining that this is too much regulation.  And
  many others are otherwise.  PGN]


Technolog - Hackers steal Walgreens e-mail list, attack consumers

Monty Solomon <monty@roscom.com>
Mon, 20 Dec 2010 23:21:58 -0500

http://technolog.msnbc.msn.com/_news/2010/12/10/5624759-hackers-steal-walgreens-e-mail-list-attack-consumers


Risks of incomplete online archives

Thomas Wicklund <tgwicklund87@gmail.com>
Mon, 20 Dec 2010 21:19:47 -0700

I recently went online looking for an article ("The Religious Success Story"
by Jared Diamond, New York Review of Books, Nov 7, 2002).  Naturally I first
found the New York Review of Books web site (www.nybooks.com).  However, I
could not find the article.  It is not found by a search, not listed in the
online contents for that issue, and not listed on the contributor page for
Jared Diamond.  A web search turned up the article at a different web site
on a page with a lot of links to the New York Review of Books web site --
I'm not sure if it's a third party site or an old site of the magazine's.

This left me wondering about the veracity of the reference to the article
(I've found references to non-existent articles periodically).  However,
finding an old print copy of a magazine is getting harder and harder.  The
two closest public libraries didn't keep more than a year or two of this
magazine, instead providing a reference to the web site for older issues.  I
finally found a hard copy of the article at the local university library,
though even there it looks like they aren't keeping more than about 10 years
of issues in the library.  Older issues are available from off-site storage,
but again the primary reference is to the magazine's web site.

This leaves me wondering about the completeness of electronic archives.
We've already lost the exact context of the print magazine (e.g.
advertising) when using electronic copies, but with libraries depending more
and more on online resources rather than keeping print archives how much
information might be lost?  Today's online storage has solved the physical
problems of aging paper or deteriorating microfilm, but now adds the risk
that content can disappear without any indication that it ever existed.

  [And then there is censorship...  Seasons greetings to the censored
  and the surveilled.  PGN]


Cell phone "emergency mode" *preventing* 911 call

Joe Thompson <joe@orion-com.com>
Tue, 21 Dec 2010 09:55:39 -0500

Last night, on my way home from picking up dinner, I passed an accident—a
car overturned in the ditch on the opposite side of the highway.  No police
or other responders had arrived, so just to be safe I decided to call it in
and dialed 911 on my cell phone (an LG enV2).

My phone went into "Emergency Mode" with no indication whether the call was
connecting or not.  At any rate I didn't hear a voice or a ringing phone.  I
hung up and dialed "911" again, with the same result.

At that point out of habit I hit "redial" rather than dialing "911" and
heard a phone ringing, but it was my wife who answered—the phone does not
add "911" to its call history, and she was the next-most-recent call.  After
a brief moment of confusion I figured out what had happened and hung up.

I dialed "911" again and this time got through to my county's
emergency-services call center, who advised that they were aware of the
accident already.

I'm perfectly willing to entertain the possibility that I made some sort of
simple error the first two times I dialed 911, but it concerns me that my
cell phone apparently interfered (or at least made things non-intuitive to
the point of interfering) at exactly the time your phone should be most
accommodating.  The inability to redial 911 from the call history
particularly worries me.  It's not hard to come up with a scenario in which
someone ends up dead because of these kinds of interface misfeatures.

Clearly the phone manufacturers (or at least LG) are trying to prevent
accidental 911 calls, but I think they may have ended up preventing
some real ones as well.—Joe


China's MIIT Declares Most VOIP Services, Including Skype, Illegal

Lauren Weinstein <lauren@vortex.com>
Wed, 29 Dec 2010 09:16:04 -0800

China's MIIT Declares Most VOIP Services, Including Skype, Illegal

http://bit.ly/iiqKhV  (DigiCha)
  [As usual, if the tiny url does not work any more, try browsing
  on the title and don't complain to RISKS.  The full info message says
  NO GUARANTEES ON URLs.  Happy New Year.  PGN]

http://www.vortex.com/lauren +1 (818) 225-2800  PFIR: http://www.pfir.org
NNSquad (Network Neutrality Squad): http://www.nnsquad.org
Lauren's Blog: http://lauren.vortex.com  https://twitter.com/laurenweinstein


Google Maps vs. USPS in Wisconsin

"Richard S. Russell" <richardsrussell@tds.net>
Sun, 26 Dec 2010 21:15:54 -0600

The US Postal Service has a flock of standard abbreviations for street
types. For example, it would prefer it if you referred to a county highway
as a "COUNTY RD", and "Street" should be abbreviated "ST", while "Avenue"
gets reduced to "AVE". (The use of all caps is commensurate with 1970s-level
OCR capabilities; I presume the USPS is trying to make its equipment last.)
Among the more obscure abbreviations are:

 * Cove > CV
 * Dam > DM
 * Divide > DV

Google Maps, in an effort to be helpful, will occasionally expand the USPS
abbreviations in its database into the full spelled-out version.

Wisconsin, unlike most other states, uses letters to designate county
roads. Usually it's only a single letter, but often enuf it's 2, sometimes
even 3.

You can see where this is headed, can't you? Starting with this view:
   http://tinyurl.com/24m4y2k
which shows County Road DM as "Co. Rd. Dam", you can zoom in a couple of
clicks to also discover "Co. Hwy. Cove" (really County Road CV) and
"Co. Hwy. Divide" (really County Road DV).

Richard S. Russell, 2642 Kendall Av. #2, Madison  WI  53705-3736
608+233-5640 RichardSRussell@tds.net http://richardsrussell.livejournal.com/


Gadgets Bring New Opportunities for Hackers

"Matthew Kruk" <mkrukg@gmail.com>
Mon, 27 Dec 2010 10:37:46 -0700

Ashlee Vance, Gadgets Bring New Opportunities for Hackers*,
The New York Times*, 26 Dec 2010
http://www.nytimes.com/2010/12/27/technology/27hack.html?_r=1&nl=todaysheadlines&emc=a25

Researchers at Mocana, a security technology company in San Francisco,
recently discovered they could hack into a best-selling Internet-ready HDTV
model with unsettling ease.  They found a hole in the software that helps
display Web sites on the TV and leveraged that flaw to control information
being sent to the television. They could put up a fake screen for a site
like Amazon.com and then request credit card billing details for a
purchase. They could also monitor data being sent from the TV to sites.

Adrian Turner, Mocana's chief executive: “Consumer electronics makers as a
class seem to be rushing to connect all their products to the Internet.  I
can tell you for a fact that the design teams at these companies have not
put enough thought into security.''


Risk Assessment and Failure Analysis ...

Rob Slade <rMslade@shaw.ca>
Tue, 21 Dec 2010 11:20:35 -0800

  [This is an OLD item that has never appeared in RISKS before.
  It's a little late for the holiday season, but still timely.  PGN]

Risk Assessment and Failure Analysis in Multiple Small Illumination
Sources During Winter Conditions
Robert M. Slade, version 1.0, 20031217

Q: How many Systems Analysts does it take to change a Christmas light?
A: None, Christmas lights are hardware.

ABSTRACT

In the author's immediate socio-cultural environment, the unpacking,
testing, placement, and maintenance of Christmas lights has been mandated to
be "man's work."  (Women will, reluctantly, direct the placement of lights,
since it is an observed fact that a man has all the artistic sensitivity of
a Volkswagen.  The car, not the automotive designers.)  Therefore, despite
the complete lack of any evidence of competence in domestic "handiness," or
knowledge of electrical appliances, the author has found himself making an
extensive, multi- year study of failure modes in different forms of lighting
involving multiple small light sources.

This paper examines the various failure modes that have been designed as
part of different formats of such lighting, and, being a confirmed
pessimist, the author conjectures about possible future design failures.

INTRODUCTION

In the middle of winter, when fogs and rains most abound, the inhabitants of
the north western parts of Europe, as well as much of North America, engage
in a frenzy of activity.  The purpose of many of these exercises is unclear.
The sociologist and cultural observer C.  S. Lewis (in an essay entitled
"Crissmas and Exmas," published in 1947 and for some reason frequently
attributed to the much older historian Herodotus) ventures that these
endeavours are religious observances in honour of a god that most of the
population does not believe exists.  On the face of it, this suggestion is
absurd.  No alternative hypothesis has, though, withstood detailed scrutiny.

We examine here the practice of the placement of additional light sources
both within and outside domiciles and business establishments during this
period.  Initial speculation that these sources provided necessary
illumination has been demonstrated to be false, despite the shortening and
weakening of daylight during this time, since a) the practice is conducted
in parts of the world where the additional lighting is not required, b) the
levels of illumination produced are insufficient for most work, and c) the
light sources appear designed to fail readily, frequently, and in such a
manner as to prevent problem rectification.

ALTERNATIVE LIGHT SOURCE DESIGNS

A variety of technologies has been used in the multiple light source
practice.  These will be examined in turn.

Candles

Originally, the light sources used were candles.  In particular, candles
were placed on or within decorated trees.  This gives some weight to the
theory of religious observance, since the practitioners would obviously
trust in God to allow them to survive the ceremony.  The candle technology
appears to have fallen out of favour with practitioners, though.  There may
be many reasons for this, such as the fact that modern cultured and
artificial Christmas trees are much denser with foliage than trees used to
be, or the fact that by the time all the candles on the tree were lit the
first would have burned out.  (In a given evening, a typical Christmas tree
requires a quantity of candles such that an equivalent amount of gasoline
would drive a Volkswagen approximately fifty kilometres.)

Candlelit Christmas trees are subject to catastrophic failure modes.  On the
positive side, there is no need to perform any maintenance or testing once a
failure has occurred.

Incandescent Bulbs

The designation and definition of incandescent bulbs, in regard to Christmas
lights, is problematic, given that at least two other forms of illumination
also use incandescent filaments, and because the word "incandescent" is
inconvenient both to write and to spell.  For the purposes of this paper,
incandescents will be defined as being subject to 120 volt electrical power
requirements, and greater than 1 cm in diameter in physical size.
Sociologically, the devotees of incandescents are considered to use
"traditional" Christmas lights.

There are, in fact, two physical sizes of incandescents.  The larger are
approximately 4 cm in length and about 2 cm in diameter.  These are
generally 7 watt bulbs, and are referred to as "outside" lights, although
they may also be used on large displays in commercial establishments
indoors, particularly where the brightness of the smaller incandescents
would not be particularly noticeable.  (See the earlier note regarding the
utility of Christmas light illumination.)  The smaller lights, usually known
as "indoor" bulbs, are roughly 2.5 cm in length and a little over a
centimetre in diameter.  In both cases the bulbs are something of a pear or
teardrop shape.

(There are a number of variations on these basic models.  Reflective or
refractive covers may be put around or behind the bulbs, and the bulb
sockets may support electrical appliances which run motors creating mobile
displays such as spinning carousels or teddy bears.  These additions do not
affect the basic failure analysis model, and so will not be considered here.
A notable exception are "bubble lights," which use the heat of the bulb to
create a continual cycle of evaporation and condensation in a tube of a
water/alcohol mixture.  Bubble lights are quite rare, and are usually stated
to be an "ironic statement in regard to kitsch" by those who are afraid to
admit that they really like them.  However, we were unable to obtain
sufficient data on failure rates, particularly in regard to explosive
failure, to add them to the models under consideration.)

Christmas lights are arranged in sets of "strings," with bases attached at
intervals along a set of power cables.  Incandescent bulbs are wired in
parallel, such that the failure of one bulb will not cause the entire string
to fail.  However, the current draw along the power cables, particularly
given the practice of joining strings together in one long string, requires
that the cabling be of significant density.  (Outdoor bulbs are generally
seven watts, and are arranged in strings of twenty five bulbs.  Therefore, a
single cable will be carrying 175 watts, or about 1.5 amps of current.
Outlining the eaves of a typical domicile will often require five strings,
placing a load of 7.5 amps at the base of the long string.  In situations
where residents illuminate trees and bushes in the yard as well, the current
load can exceed this by a substantial margin.)  Therefore, incandescent
strings are based on heavy gauge wire, with correspondingly heavy
insulation.  (It should be noted that, despite the identical power
requirements, "indoor" and "outdoor" incandescent bulbs have proportionately
sized bases, ensuring that neither can be used in the strings of the other,
and requiring that replacements be available for both sizes.)

Incandescent strings are therefore not subject to simple failures that would
occur in lighter equipment.  They are, though, very difficult to manipulate,
store, and retrieve from storage.  This ensures that bulbs fail frequently
due to mishandling during the manipulation process known as "putting the
lights up" or the corresponding "putting the lights away."  Some light
practitioners have therefore undertaken to putting lights (particularly
outside lights) in place, and then leaving them there.  However, Christmas
lights are, as noted, not designed purely for illumination: they are
coloured, so that the ultimate effect of Christmas lights is similar to that
of seeing a multitude of different coloured Volkswagens in a parking lot.
The bulbs have been designed in two ways.  The first applies colour as
coloured paint, ensuring that any bulbs left outside for long periods of
time become scratched by branches and thus become colourless.  The later
design is to apply the colour with a film of plastic: this design ensures
that the film degrades with the "hot/cold" cycle that is engendered by bulbs
that are turned on for brief periods during cold weather.  The film
eventually flakes off, again leaving the bulbs with limited colour.

Minilights

Minilights use incandescent filaments, but are much smaller than the more
traditional incandescent bulbs.  Minilight bulbs are roughly .5cm in
diameter and 2 cm in length.  The bulbs sport two bare wires, and must be
mounted in a separate base before being placed in a string.  There is no
difference whatsoever in size, form, or markings regardless of whether
minilight bulbs are 2 volt, 2.5 volt, 3, 3.5, 4, 5, 6, 7, 8, 10, or 12 volt,
nor whether they are ordinary bulbs or "flashers."  (Flashing bulbs are
known to trigger seizures in those subject to epilepsy, and extreme
agitation and annoyance in most of the rest of the population, similar to
the Netscape <blink> blink </blink> tag, or following a Volkswagen for
thirty two miles down the freeway with the left turn flasher stuck on.)
There is also no particular indication that a bulb is dead, other than the
fact that it does not work.  (Traditional incandescent bulbs are generally
large enough that the filament is visible to the naked eye, except, of
course, if the bulb is of the painted variety.)  Despite the universal
nature of the bulb sizes, the bases for minilights vary from string to
string, and many strings will, in fact, have multiple incompatible sizes of
bases that must be used in the correct sockets along that string.

Minilight bulbs are strung in series.  A rough estimate of the voltage
requirement for a string may be obtained from the number of sockets, but
this is not a completely reliable indication.  (Many strings are, in fact,
multiple strings, wired in parallel with each other.  Therefore, a failure
may leave half the string usable, but use of such a string is seen as an
admission of failure of manhood (see above in regard to gender roles in
respect of Christmas lights).

Minilight bulbs, being strung in series, would be subject to complete
failure of a string if a single bulb were to burn out.  The bulbs are,
therefore, designed such that the burning out of a bulb also creates a
"burn-through" in order to maintain the electrical circuit.  As with all
religious practices there is an attendant element of randomness: sometimes
the burn-through works, and sometimes it doesn't.

Because of the universal size, bulbs of differing voltage may be used in a
single string, or bulbs of an inappropriate voltage may be used in a string.
When, for example, twelve volt bulbs are used in a string wired for seven
volt bulbs, the bulbs will work, although they will burn very dimly.  Seven
volt bulbs may also be used in a string wired for twelve volt bulbs.  This
practice is much more interesting.  Due to the higher temperature and
stress, eventually a bulb will burn out.  However, due to the burn-through
design, this will still leave the rest of the string burning and will, in
fact, increase the brilliance of the illumination.  This also increases the
thermal stress, though, and therefore an additional bulb will blow out in a
lesser period of time.  After the failure of one or two more bulbs, the
whole string goes in rapid succession: in the words of one observer, "like a
string of firecrackers."

Because of the universal bulb size, the lack of differentiation between live
and dead bulbs, and the bulb burn-through design, failure analysis of a
string is problematic.  There is the practice of individually removing each
bulb and socket, removing the bulb from the socket, and replacing it with a
bulb known to be good.  This procedure has been cited in the psychological
literature due to its relation to serious nervous conditions that result
when the practitioner realizes that he has been testing with a bulb that is
actually dead, or fruitlessly comes to the end of a test of several strings
and realizes that it was more than possible that multiple bulbs on the
string were dead.  (This assessment is also complicated by the randomness of
the burn-through factor noted above.)  Experienced practitioners (if they
escape the nervous conditions noted above) find that bulbs and sockets must
be individually removed, the bulb removed from the socket, and tested by
placing it into a socket of a string that is known to be good.  Frequently
as many as a quarter of the bulbs on a string must be replaced before the
string becomes usable again, and even then a number of bulbs can be
identified as needing to be replaced for full illumination.  (As noted,
complete illumination has no functional purpose, but is practiced by the
masters of the craft as a prophylactic against string failure during the
Christmas season.)

Light Ropes

Light ropes combine the failure characteristics of minilights with the
difficulty of manipulation of traditional incandescents, and add the ease of
maintenance of spy satellites (as opposed to, say, original model
Volkswagens).  Also, many religious leaders hold them to be an abomination
and offence against nature.

LEDs

The latest technology in Christmas lights involves Light Emitting Diodes, or
LEDs.  LEDs provide a much greater efficiency of conversion of electricity
to light than do other forms of lighting technology.  In addition, the
manufacturers of LED Christmas light have chosen to go the conservation
route.  Door and Window outlining of a typical domicile can be achieved for
the entire Christmas season (with the lights left on 24 hours per day) for
roughly the cost of a local call on a pay phone (if you can find one, in
these days of ubiquitous cellular phones).  Unfortunately, the level of
illumination provided is quite low: the entire light output of several
strings is scarcely enough to allow you to find your way around the inside
of a Volkswagen.

LEDs are wired in series, like minilights, and are designed with the same
burn-through technology.  As well as being more efficient, LEDs are also
said to be more durable, although this, being a new technology, has not been
put to practical tests.  Therefore, it is felt that LED Christmas light
strings will be longer lasting, and the manufacturers boast of a five-year
guarantee.  This promise is marred by only two considerations.  The first is
the low probability that the manufacturers are in any danger of having to
provide replacements for such a low cost item.  The second is the fact that
the light strings are also said to be resistant to a failure of a single
bulb, but have absolutely no provision for replacement: all bulbs are
hardwired into the string.  If a second bulb goes, you are supposed to throw
the string away.

CONCLUSION

Given the failure characteristics of Christmas lights, the hypothesis of
religious observance (similar to penitential exercises seen in other cases)
must be supported, even in the complete absence of evidence of a belief
system.

The author wishes the readers a very Merry Christmas and a Happy New Year.
(Failing that, the author wishes the readers a very happy Generic Mid-Winter
Party Period.)

ACKNOWLEDGMENTS

This work has been supported by research performed by Erichson
Engineering, the Vancouver Centre of Excellence of Honeywell Process
Solutions, and Gloria J. Slade.

rslade@vcn.bc.ca     slade@victoria.tc.ca     rslade@computercrime.org
victoria.tc.ca/techrev/rms.htm blog.isc2.org/isc2_blog/slade/index.html
http://blogs.securiteam.com/index.php/archives/author/p1/
http://www.infosecbc.org/links http://twitter.com/rslade

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