The Hound of the Baskerville's

Copyright Dr Alan Solomon (1986-1995)

Holmes was puffing on a foul-smelling pipe, and looking bored.  I
always worry when Holmes is bored, as he has a habit of reverting to
his most disgusting habit - one that is an offense to any civilised
man.  Indeed, the sound of Holmes's violin has been known to bring
tears to the eyes even of the tone-deaf.

"Mark my words well, Watson", he said to me, "Our next visitor was a
wealthy man until the great Stock Exchange crash, but is now of very
modest means." "What visitor?" I asked, but before Holmes had a chance
to answer there was a knock at the door, and Mrs Hudson ushered a very
agitated gentleman into our rooms.

"You were a stock broker, but are now unemployed", said Holmes.
Dumbfounded, the man stared at Holmes.  "You earned an excellent
salary, but but following the Great Crash, now you are penniless." The
man was clearly speechless with amazement.  "Amazing, Holmes", I
cried, "How do you make these astounding deductions?" "Elementary, my
dear Watson.  Observe his Astrakhan coat, of the very finest quality,
but now looking somewhat the worse for wear.  And observe also the
Filofax peeking from his pocket.  All the hallmarks of a successful
Stockbroker in the City, but obviously who cannot afford the
accouterments of success any more.  I would venture to suggest that
you wish to consult me on a case involving fraud." "Incredible Holmes
- your powers of deduction are without parallel," I enthused.

The man spoke for the first time.  "Well actually, you're a bit off
target.  I bought the coat at a jumble sale;  the "Filofax" is a cheap
imitation from Rymans, and I never was a stockbroker, never had a
fortune, and never lost one.  And I'm not unemployed;  I'm a bank
clerk, with Baskerville's.  You know them?  They have a big black
hound as their logo.  You're right about the fraud, though." "Holmes,
your logic has once again arrived at the correct conclusion - I
applaud you," I said.

The bank clerk had a sorry tale to tell, once we stopped Holmes from
making silly guesses.  He stood accused of fraud to the tune of half a
million pounds, and looked certain to be convicted.  "There seems to
be no way I can prove my innocence", he said.  "I was the only one who
knew the code words giving access to the accounts that were
defrauded." "But you are innocent?", said Holmes.  "Yes, I swear it."
Then there must be another way to access these accounts.  All we have
to do is find it." "But how will this prove our client's innocence?" I
asked.  "It won't", said Holmes.  "But we don't need to prove his
innocence - all we need to do is cast reasonable doubt on the case for
the prosecution, which we can do by showing that there is another way
to access these accounts." The bank clerk looked somewhat relieved at
the prospect of the Great Detective working on his case, and when he
had gone, we sat down and did some serious thinking.

Holmes, of course, knew nothing about computers.  His idea of a data
base system is a box of three by five cards, and indeed he kept his
famous database of tobacco ash in this way.  But fortunately, my own
practise is not at all medical - I specialise in unusual computer
problems.  So Holmes didn't have far to look for some brains to pick.

We decided that the best way to establish our client's innocence,
would be to demonstrate the vulnerability of the bank's systems to
outside interference.  But hacking into a bank's computer systems can
easily be misunderstood, and the fuzz get pretty heavy with people
caught doing this.  So first, we went to visit Inspector Lestrade of
the Yard, to explain what we were about.  Lestrade was heavily
sarcastic.  "You two stand about as much chance of breaking into a
bank's computers as a teenage hacker would in breaking into the Tower
of London." I refrained from pointing out that Schiffreen had indeed
broken into the Prince Philip's Mailbox;  all we needed to do was
establish our innocence should we be caught at this enterprise.
"Certainly, you can try", laughed Lestrade, "and should you get
caught, I think I can guarantee that you will not be prosecuted, but
you would certainly become a laughing stock", he promised.

Our first move was to purchase an Amstrad PPC1640 with integral modem.
We would need this to penetrate the bank's defences.  Any hack
consists of finding out three things - the correct phone number, a
suitable user name, and a password.  Once you have all these, the
world is your oyster.  We also opened a fictitious bank account, as a
place to deposit our ill-gotten gains.  This Holmes did, in disguise.
I wish he'd get rid of the hunchback outfit - it isn't at all
convincing, and it makes him look rather conspicuous.  I was
impressed, though, with the fact that he came back with the bank's
computer access telephone number;  that would make our task much
easier.  I asked him how he did it.

"Simple", he said.  "I explained that I was opening an account for a
major corporate customer, and they immediately began to fawn over me.
The hunchback disguise worked a treat - they assumed that a mental
deficiency must go with the physical deformity, and when I asked if I
could be given a glimpse of their famous computer system, they very
proudly showed me round.  Unfortunately, they didn't actually show me
their computers, just their communications room - the computers are in
Birmingham.  It was still useful, though;  the incoming modem stack
was in the corner of the computer room, several of the phone numbers
were written on the sides by the test engineers, and I just memorised
those."

"Now, Watson, to work.  The game's afoot." He often said that, and to
this day I cannot work out what it means.  What game?  What foot?  I
fired up the PPC, told the modem to autodial the number, and the modem
at the far end answered.  The answer was gibberish, but it didn't look
like line noise.  The remote modem was obviously encrypting, and I
didn't know the key.  I typed Help, and pressed return a few times,
and was rewarded with screenfuls of gibberish, which I carefully
logged to disk.  I then printed this out, and gave it to Holmes.  "You
know what to do, Holmes?" "Yes", he said, "Mycroft."

Mycroft is Holmes's brother.  Mycroft is a genuine mathematician where
Holmes is more of a generalist.  Mycroft works for the foreign office,
and is something to do with cryptography - more than that I am not at
liberty to reveal (i.e., if I were to reveal more, I would not be at
liberty).  The prime requirement of a cryptographer is a sample of
encrypted text, and the bank's computer had very kindly provided us
with that.

While Mycroft worked on the encryption system, I logged into a few of
the hacker bulletin boards around the country.  A number of bulletin
boards have a hacking area, in which phone numbers, user names and
passwords are exchanged.  Most hackers do it for fun;  the thrill of
logging into a big computer that you are not supposed to be on, and
the boast afterwards to friends.  Most big computers are appallingly
easy to log on to - Hugo Cornwall wrote a book called the Hacker's
Handbook in which he showed how many people left their computers
totally vulnerable to hacking.  Two years later, a few of those
computers still had exactly the same security holes.

I posted a message on several boards, asking if anyone knew of a user
ID (and ideally a password) for this phone number;  if anyone did,
could they please post an answer on my own Fido.  I also phoned up a
few friends to see if they'd met this machine before, and if so, did
they have any information.  One of them was able to tell me that the
machine at the Birmingham site was a VAX, which was nice, because I
know the VAX well, and have a set of documentation for it.

Mycroft came back to me with no joy.  He said that having encrypted
data was not very useful, unless I could give him at least some idea
of what the plaintext looks like.  "Elementary, my dear Mycroft", I
said, and explained that it was almost certainly the VAX login help
messages, and photocopied the pages in the manual that showed what
they said.  Armed with this information, Mycroft was able to break the
code in a week or so.  Unfortunately, none of the hacker boards had
turned up with a user ID, let alone a password.

Holmes really can be quite clever sometimes.  "The Finance Director
will have an ID into the system", he said.  "Yes," I said, "and it is
common practice for VAXes to use the person's initial and last name as
the ID, such as sholmes or jwatson." Holmes got a copy of the company
annual report, and from this we discovered that the Finance Director
was one Samuel Garrett.

Next, I had to write a communications program.  In the bank's genuine
system, the modems automatically encrypted and decrypted the data,
which is a very sound security system.  Obviously, we didn't want to
attract attention to ourselves by purchasing one of these special
modems, so I had to do the encryption/decryption in software.  I took
PC-Talk (a shareware communications package) as my starting point, as
it comes with source code.  I added the encrypter/decrypter to it,
compiled it, and found that even with this overhead, it ran fast
enough on the PPC to do 2400 baud.

We then dialled up the bank.  Sure enough, the remote computer
announced itself.  "Baskerville's Bank Data Entry VAX number 3" it
announced itself.  I do love it when you hack a computer and it tells
you that you've found the right machine.  Then it said "Username:" and
I typed "sgarrett".  It then came back "password:".  I tried "fred",
and it came back "Illegal password, try again." I tried "pass" and
"secret", but after three wrong tries, it logged me off.  "Rats", said
Holmes.  "We've failed." "Au contraire, my dear Holmes, we have
succeeded beyond my wildest expectations."

I explained.  We now had the correct phone number, and we also knew
that we'd correctly broken their encryption system.  We were getting
on to the right computer, and the VAX was telling us that we had the
wrong password.  Not, you notice, that the username didn't exist, or
(as it should have) that the username/password combination was
illegal.  Just that we had the wrong password.  So now all we had to
do was get sgarrett's password.

There is a list of ten common passwords that everyone uses.  You've
seen three of them above;  others are password, sex, letmein, open,
1234 and a couple of obscene ones.  If you use any of these, change it
at once.  After that, people use their first names, their
wives/husbands, sons and daughters, car registration numbers and other
easily remembered names.  We looked Mr Garrett up in Who's Who, and
tried a few likely names, his birthday, and his old college.  Holmes
went down to his country house, and spent a couple of days watching.
He returned with a good list of car numbers, house names, friends
names and so on - we tried them all, to no avail.  "What about his
hound's name?" I said.  "Fido", said Holmes, but it was no use.
Finally, I said to Holmes that I was going to use the Ultimate Weapon.

Real Hackers don't use this method - it's a bit like dynamiting fish
in a barrel.  There's no sport to it, and you can't really boast about
it afterwards.  But it does have this advantage - it is pretty
foolproof.  I've never known it not to work.  "Hello", I said when I
was put through, "Mr Garrett?" "Yes", he said.  "Computer department
here - we need to do some work on your account.  Could you give me the
password?" And of course he did.

The rest was simple.  We logged on to the VAX, and using the privilege
that the Finance Director of Baskerville's Bank has, we transferred a
large sum from the accounts that he had access to into our fictitious
account.  Of course, this would soon be noticed, but our point would
have been proved.  Next, Holmes donned his hunchback disguise, went
down to his branch, and made a major withdrawal.  Because this was
done the same day, the computer didn't have a chance to discover that
there was no corresponding transaction to balance the robbed accounts.
This was put into a suspense account for dealing with manually later;
computers often make monumental blunders that have to be put right
later by real people.  But in the meantime, Holmes arrived back at our
digs with a large hamper, and when he opened it, he revealed that
where one might have expected to find cold chicken and champagne,
there were bundles and bundles of fivers.

"Now we can take this to Inspector Lestrade and prove our client's
innocence", Holmes said.  "Yes", I said.  "Yes", Holmes said.  There
was a pause.  The pause turned into a silence.  The silence lengthened
into a period of extensive meditation, during which both Holmes and I
wrestled with our consciences.

It's nice here in Rio;  the weather's warm and the natives are
friendly.  Our client wasn't proved innocent, but he doesn't seem to
care - we bumped into him on the beach last week.  The main loser
seems to be Samuel Garrett.  It seems that he's being accused of all
sorts of nasty things, and doesn't seem to have a leg to stand on.
Still, it serves him right.  By the way, if anyone, ANYONE, asks you
your password, don't ever give it.


Disclaimer

This is a work of fiction.  There is no such person as Sherlock
Holmes.  Even if there were, there is no such person as Doctor Watson.
Even if there were, there is no such bank as Baskerville's and it
doesn't have a black hound as its logo.  Even if there were such a
bank, they would not be so stupid as to take someone on a guided tour
and give away a secure telephone number.  Even if they did, banks use
codes that are unbreakable.  Even if the codes were breakable, people
don't use initial-lastname as user identities.  Even if they did, they
don't choose their passwords from a short list of common ones.  And if
they didn't, they obviously wouldn't reveal their password over the
phone.  Anyway, no bank would allow someone disguised as a hunchback
to withdraw a million pounds without some very good proof of identity.
And there is an extradition treaty between Brazil and the UK, so you
can't get away that way.

Not only is this a work of fiction, the whole thing is obviously
totally impossible. The weather is nice, though.