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Chapter 12 • Responding to Botnets
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Abad speculates the reason these banks are in such demand is because their
tracking algorithm is easy to obtain from other phishers.This demand, he
concludes, is created by the ability of the casher to cash out a given financial
institution; thus, restricting the ability of the casher to cash out reduces
demand.
Hard Problems in Software Engineering
From the traditional computer science point of view, a couple of points need
to be made. One is that our problem is indeed hard. For example, one of the
founding fathers of computer science, Alan Turing, showed that we could not
write a program that could decide if another program was going to halt the
computer. (For example, see http://en.wikipedia.org/wiki/Halting_problem).
This was called the 
halting problem
. A poor student of computer science
might decide that this problem only applies to programs looking for halt
instructions in other programs. After all,Turing mathematically proved that
the program searching for the flaw cannot find all instances of it.The more
astute student understands the general implications. In practical terms, we
can’t get all the bugs out of a software program or system. For example, in
security terms, consider a virus checker looking for “signatures” (patterns) in
random files on your Windows box.Turing told us that by definition this pro-
gram cannot be perfect. A virus may exist that the program cannot detect.
This is a fundamental result in computer science.
Furthermore, we know that our systems only seem to get more compli-
cated. We now have dynamic link libraries and loadable device drivers and it
isn’t clear where the operating system ends and applications begin. Microsoft
may have a lot of software, but they also have created a large market for third-