Information Technology Reference
In-Depth Information
computer guessing an account on another computer, many systems
will stop accepting attempts to log in if passwords are consistently
wrong, or alarms may be triggered to warn of attempted breakins.)
In general, gaining access to one machine or to an account
on one machine often opens up many ways to break into other
accounts.
Trojan Horses: Another way people can interfere with your
work involves the exploitation of generally accessible file areas.
These file areas would include commonly used programs that may
be grouped in a directory that many people can access. Routine ad
ministrative tasks using materials in these file areas may be done au
tomatically by running programs stored in special locations. Under
normal circumstances, these activities would not pose any problems.
If security measures within a system are somewhat lax, however, a
clever user might be able to introduce a new program into a system
area, and this program then may be run automatically as part of ad
ministration or accidentally by another user. If the foreign program
were to copy sensitive data or grant special privileges, then the orig
inal user might gain access to restricted information. These pro
grams are called
Trojan horses
; unfortunately stories of security vi
olations that are due to Trojan horses are quite common.
Viruses and Worms: Two other types of subversive programs
that can undermine system security and reliability are viruses and
worms. The mechanics of these programs differ in their operation
and in the ways they spread through a system, but the ideas behind
both viruses and worms are reasonably similar. Each case affects the
functioning of an operating system by entering a machine from a
source that is trusted to be secure. Once within the machine, the
program is run and it affects the further operations of the machine.
Sometimes the effects may be harmless, but in other cases data may
be lost or modified, or a system may be unable to continue function
ing. In each case, system security has been breached, and system
users may no longer know what operations and data are reliable.
(As a preventative method several years ago, one major company
shut down its computer operations on a Friday the 13th, because of
rumors of difficulties that might occur when that date was reached.)
Viruses
typically are transmitted in email or on diskettes that
are used on one machine and then another. When a user receives a
virus via email, the text itself may be reasonably safe; however, if
the email contains an attachment, then opening the attachment
may run a program (such as a word processor or spreadsheet) that
activates the virus within that attachment. To expand on this some
