Viruses, Trojans and Worms on your computer are bad. The terms are
often used interchangeably, but each is distinctly different.
A computer virus attaches itself to a program or file, enabling it to spread
from one computer to another, leaving infections as it travels. Like a
human virus, a computer virus can range in severity: some may cause
only mildly annoying effects, while others can damage your hardware,
software or files. Almost all viruses are attached to an executable file,
which means the virus may exist on your computer, but it actually cannot
infect your computer, unless you run or open the malicious program.
A VIRUS cannot be spread without a human action, (such as running an
infected program) to keep it going. Because a virus is spread by human
action, people will unknowingly continue the spread of a computer virus
by sharing infecting files, or sending emails with viruses as attachments
in the email.
A WORM is similar to a virus by design, and is considered to be a subclass of a virus. Worms spread from computer to computer, but unlike a
virus, it has the capability to travel without any human action. A worm
takes advantage of file or information transport features on your system,
which is what allows it to travel unaided. The biggest danger with a worm
is its capability to replicate itself on your system, so rather than your
computer sending out a single worm, it could send out hundreds or
thousands of copies of itself, creating a huge devastating effect. One
example would be for a worm to send a copy of itself to everyone listed in
your e-mail address book. Then, the worm replicates and sends itself out
to everyone listed in each of the receiver’s address book, and the
manifest continues on down the line. Due to the copying nature of a worm
and its capability to travel across networks, the end result in most cases
is that the worm consumes too much system memory (or network
bandwidth), causing Web servers, network servers and individual
computers to stop responding. In recent worm attacks such as the much talked-about Blaster Worm, the worm has been designed to tunnel into
your system, and allow malicious users to control your computer
remotely.
A TROJAN HORSE is full of as much trickery as the mythological Trojan
Horse it was named after. The Trojan Horse, at first glance will appear to
be useful software, but will actually do damage once installed or run on
your computer. Those on the receiving end of a Trojan Horse are usually
tricked into opening them because they appear to be receiving legitimate
software or files from a legitimate source. When a Trojan is activated on
your computer, the results can vary. Some Trojans are designed to be
more annoying than malicious (like changing your desktop, adding silly
active desktop icons), or they can cause serious damage by deleting files
and destroying information on your system. Trojans are also known to
create a backdoor on your computer that gives malicious users access to your system, possibly allowing confidential or personal information to be
compromised. Unlike viruses and worms, Trojans do not reproduce by
infecting other files, nor do they self-replicate.
Use good virus protection software. We like Avast (CZ), AVG (NL),
TotalAV (UK), Norton (US), PC-Matic (US). All have free versions! but
there are many others out there. McAfee (US) tends to use a lot of
system resources, so it noticeably slows some systems, especially older
machines.
Install a good firewall. Most virus protection software suites include a
firewall built in.
Keep your operating system updated. Windows can easily be set to
update in the middle of the night for you. Windows will patch any exploits
it finds for free, there is no logical reason not to stay updated. While
updating Windows, also periodically update other software running on
your computer.
Use caution when opening files received by email, or clicking on links. If
you don’t know who sent you some files, better to leave them unopened,
until you can verify who sent them to you. Note, a good virus program will
always check incoming email for infections, yet another reason to have
one!
According to the FBI, slightly over 80% of all infections occur when
someone opened a file that arrived by email.
Think about it!