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Modern Operating Systems by Herbert...
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consist of thousands (and sometimes millions) of compromised computers—often
normal computers of innocent and ignorant users. There are all-too-many ways in
which attackers can compromise a user’s machine. For instance, they may offer
free, but malicious versions of popular software. The sad truth is that the promise
of free (‘‘cracked’’) versions of expensive software is irresistible to many users.
Unfortunately, the installation of such programs gives the attacker full access to the
machine. It is like handing over the key to your house to a perfect stranger. When
the computer is under control of the attacker, it is known as a
. Typi-
cally, none of this is visible to the user. Nowadays, botnets consisting of hundreds
of thousands of zombies are the workhorses of many criminal activities. A few
hundred thousand PCs are a lot of machines to pilfer for banking details, or to use
for spam, and just think of the carnage that may ensue when a million zombies aim
weapons at an unsuspecting target.
Sometimes, the effects of the attack go well beyond the computer systems
themselves and reach directly into the physical world. One example is the attack on
the waste management system of Maroochy Shire, in Queensland, Australia—not
too far from Brisbane. A disgruntled ex-employee of a sewage system installation
company was not amused when the Maroochy Shire Council turned down his job
application and he decided not to get mad, but to get even. He took control of the
sewage system and caused a million liters of raw sewage to spill into the parks,
rivers and coastal waters (where fish promptly died)—as well as other places.
More generally, there are folks out there who bear a grudge against some par-
ticular country or (ethnic) group or who are just angry at the world in general and
want to destroy as much infrastructure as they can without too much regard to the
nature of the damage or who the specific victims are.
Usually such people feel that
attacking their enemies’ computers is a good thing, but the attacks themselves may
not be well targeted.
At the opposite extreme is cyberwarfare. A cyberweapon commonly referred
to as
physically damaged the centrifuges in a uranium enrichment facility
in Natanz, Iran, and is said to have caused a significant slowdown in Iran’s nuclear
program. While no one has come forward to claim credit for this attack, something
that sophisticated probably originated with the secret services of one or more coun-
tries hostile to Iran.
One important aspect of the security problem, related to confidentiality, is
: protecting individuals from misuse of information about them. This quickly
gets into many legal and moral issues.
Should the government compile dossiers on
everyone in order to catch
-cheaters, where
is ‘‘welfare’’ or ‘‘tax,’’ depending
on your politics?
Should the police be able to look up anything on anyone in order
to stop organized crime?
What about the U.S. National Security Agency’s moni-
toring millions of cell phones daily in the hope of catching would-be terrorists?
Do employers and insurance companies have rights? What happens when these
rights conflict with individual rights?
All of these issues are extremely important
but are beyond the scope of this book.

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