(Hmm, it's time for my bi-yearly DST rant. Here goes.)
One of the many lame excuses given for daylight savings time is that it
cuts down on crime, since more crime occurs after dark. This might be true
of violent crime, since fewer people will be out after dark, but what about
other crimes? It's interesting to think about ways that criminals could
exploit possible confusion, broken data-keeping, etc around the
discontinuity caused by daylight saving time changes.
Q: Where were you on the night of October 30th 2005 between 1 and 2 am?
A: Well, I was at this bar with my friends that whole hour, I have an alibi.
Ok, that's a bit easy to catch (although there's a
real life
story of a similar trick
being used to avoid manslaughter charges), but what about more subtle cheats?
All-night workers last night could pretty easily cheat their employer out
of an hour's pay, for 2 am to 3 am. Conversely, if they're not careful,
their employer might cheat them next fall. The only people I've ever heard
discuss this are all-night radio jockies, but those guys love to hear
themselves talk enough that an extra hour to do it in is not a problem to
them. I'll bet that a fry cook would rather get some extra sleep.
But this is still small, er, potatoes. For really nice exploits you have to
take advantage of explicit failures of technology. One such failure is in
the way Windows manages daylight savings changes. Unlike Unix, which
elegantly flips between two time zones, such as EST and EDT, but still
keeps counting each second from Jan 1st 1970, Windows actually
changes
the clock.
Despite a brainwashed nation that has been taught that moving the hands
back or forward is the right thing to do, in the world of computers, it's
bloody stupid. A google for "daylight savings windows bug" turns up a
million or so hits caused by this behavior, describing problems like this:
Windows reports erroneous file modification times, which change according to
daylight savings.
And this:
When Windows NT automatically adjusts for daylight savings time, the times
on files on Windows NT file system (NTFS) partitions and the events in the
event logs are retroactively shifted by one hour, even though the files and
event records were created before the daylight savings time change.
Now, I think there's all kinds of potential for criminal fun in file
modification timestamps being wrong, and log files having innaccurate
times. Throw in the odd backup that fails to run due to being
scheduled to run at a time that never exists, and the time slip begins to
seem like an ideal time for shady activities. (And a very poor time to be
in a hospital hooked up to windows-controlled life-support equipment.
Double-dose of morphine, anyone?)
True story: A year ago I was at a fancy hotel, which was burgalarised. This
hotel had electronic locks on the doors, which logged when the doors
were opened, and by whom. The techies whose possessions were stolen were
able to use this information, plus what they knew about when the theft must
to have occurred, to narrow down the suspects to one or two hotel employees
who opened the door at the right time. If those logs went to a machine
running windows and the theft occurred during England's change to DST, it's
quite possible the logs would have been useless.
It's not too far from this kind of scenario to something suitable as an
entry in Schneier's
movie-plot terrorist
threats
contest. Although it's worth noting that the airline industry deals with
timezone changes all the time, so if they have any sense, the DST change
is not an exceptional event for them. One of the interesting things about
plane travel to me is the way a plane in flight between timezones is a
space in which no defined time zone exists. But I digress..
I suspect that the real source of fetile bugs related to DST is in the
interstices between operating systems where programs have to deal with the
peculuarities of multiple OSes to behave correctly. Such as
this unison/linux/windows bug.
Put different systems together and they fail in myriad ways, and there's
room in the cracks for criminal activity.
Thing is, I don't have a very good criminal mind, at all, so if any of the
slightly weak approaches I've detailed above is feasable, it seems to me
there must be some terrific scams, techniques, etc, that people who are
good at thinking that way, and have the right motivation can use.
Friday 30th March:
In the space of seven short days, they've managed to go from hard-line
right-wing, give us tax cuts, don't "throw it away" on the state; to
full-on fund the NHS more "Daily Express Crusade" your childen are All
Going To Die.
If these headlines were in