PC Security: Computer Viruses
Know Thy Enemy is rule number one when it comes to computer
security. You can't fight or prevent something effectively if you have no
idea what you are guarding against. In the online world, there are many
enemies.
Those computer users known as Crackers and Hackers are the enemy. Crackers
typically break into a system for the purpose of doing damage. Hackers, on
the other hand, often break into systems just to see what is there, without
any intention of doing harm. In fact, most large corporations, such as financial
institutions, hire hackers on a full time basis. The hackers job is to try
to break into the computer system. This is how the security holes are found
and fixed. So, in this sense, most hackers are actually not the enemy, however
there are people out there that call themselves hackers, who are actually
crackers.
These people do more than break into systems, however. They also write malicious
programs known as malware, such as viruses, worms, and trojan horses. A virus
is a program that is typically hidden within another program. These are commonly
delivered via email, in the form of attachments. The virus, once it has installed
itself, looks for a host program. When the program runs, the virus runs.
Once it runs, it is usually able to do what it was meant to do, and to infect
other programs. It will even send itself to everyone in your address book.
Viruses operate in various stages. The first stage is the delivery, followed
by the installation, infection, and finally the destruction phase. A virus
may lay quietly on your hard drive awaiting a certain event, such as a certain
date to trigger it. It will then deliver it's 'payload' which may mean file
or program corruption, file deletion, messages, or even destruction of the
operating system, leaving your computer unusable.
When computer viruses first made their appearance in our online world, they
were commonly distributed via floppy disks. Today, however, they are delivered
in downloadable executable files and email.
Worms are much like viruses. They can reproduce themselves, but they can
also infect other systems on a network without a human doing anything further.
Worms do not need host programs, and they do not need executable files to
hide in, although they can also be delivered via email.
While viruses commonly infect individual systems, worms infect entire networks
of computers. They commonly overload and overwhelm the resources for the
network, which in turn causes data transmission slow down. Worms commonly
insinuate themselves onto systems using a backdoor program. A backdoor is
common for most networks, and it bypasses the login. Most programmers often
leave a backdoor in a program so that they can easily get into the system
or program if they need to for legitimate reasons.
A trojan horse is a program that the user thinks does one thing, but actually
does another. When you think of a trojan horse, think of the Greeks. Remember
that they built a large wooden horse to hide in, and the Trojans believed
that the Greeks were giving them a gift, and took it into their compound
walls. Once inside, the Greeks attacked the Trojans.
Trojans do not reproduce themselves. The software that they hide in may be
quite useful in fact, but the trojan may erase files or data, corrupt programs,
log keystrokes, and of course will usually install a backdoor program for
other trojans to easily enter through. Trojans are commonly used to steal
personal (read financial) information.
Virus software is the first line of defense against all of these threats,
but it usually is not enough. For example, many virus detection programs
won't detect worms, some won't detect trojan horses, and most won't detect
spyware or adware. You should make sure that your virus definition is always
up-to-date, install an anti-spyware program, spam blockers, and of course
special software that detects trojan programs and worms as well, if your
anti-virus program does not.
 PC Security: Index
PC Security:
Internet Browsers
PC Security:
Spam
PC Security:
Stopping Spam Part 1
PC Security:
Stopping Spam Part 2
PC Security: Spam
Scams
PC Security:
Email Security and Spam
PC Security:
Email Security
PC Security:
Computer Viruses
PC Security:
Protecting Computers From Viruses
PC Security:
Worm Viruses
PC Security:
Trojan Horse Viruses
PC Security:
Rootkits
PC Security:
Removing a Virus
PC Security:
Virus Hoaxes
PC Security:
Server Viruses
PC Security:
Home Network
PC Security:
Cell Phone Viruses
PC Security:
Spyware
PC Security:
Firewalls Part 1
PC Security:
Firewalls Part 2
PC
Security: Parental Control Software
PC Security:
Malware - Spyware and Adware
PC Security:
Data Backups
PC Security:
Pop Up Windows
PC
Security: Safe Public Computer Use
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