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Chapter 7: Passwords
The National Vulnerability Database (an index of computer vulnerabilities
managed by the National Institute of Standards and Technology) currently
identifies over 2,500 password-related vulnerabilities! You can search for
these issues at http://nvd.nist.gov to find out how vulnerable some of
your systems are from a technical perspective.
Cracking Passwords
Password cracking is one of the most enjoyable hacks for the bad guys. It
fuels their sense of exploration and desire to figure out a problem. You might
not have a burning desire to explore everyone’s passwords, but it helps to
approach password cracking with this mindset. So where should you start
hacking the passwords on your systems? Generally, any user’s password
works. After you obtain one password, you can often obtain others — including
administrator or root passwords.
Administrator passwords are the pot of gold. With unauthorized administrative
access, you (or a criminal hacker) can do virtually anything on the
system. When looking for your organization’s password vulnerabilities, I
recommend first trying to obtain the highest level of access possible (such as
administrator) through the most discreet method possible. That’s often what
the bad guys do.
You can use low-tech ways and high-tech ways to exploit vulnerabilities to
obtain passwords. For example, you can deceive users into divulging passwords
over the telephone or simply observe what a user has written down
on a piece of paper. Or you can capture passwords directly from a computer,
over a network, and via the Internet with the tools covered in the following
sections.
Cracking passwords the old-fashioned way
A hacker can use low-tech methods to crack passwords. These methods
include using social engineering techniques, shoulder surfing, and simply
guessing passwords from information that he knows about the user.
Social engineering
The most popular low-tech method for gathering passwords is social engineering,
which I cover in detail in Chapter 5. Social engineering takes advantage
of the trusting nature of human beings to gain information that later can
be used maliciously. A common social engineering technique is simply to con
people into divulging their passwords. It sounds ridiculous, but it happens all
the time.
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