|
What is a computer
virus?
A computer virus is a program - a piece of executable code - that has the unique
ability to replicate. Like biological viruses, computer viruses can spread quickly
and are often difficult to eradicate. They can attach themselves to just about
any type of file and are spread as files that are copied and sent from individual
to individual.
Besides replication, some computer viruses have something else in common: a
damage routine that can deliver the virus payload. While payloads may only
display messages
or images, they can also destroy files, reformat your hard drive, or cause
other kinds of damage. If the virus does not contain a damage routine, it can
still
cause trouble by taking up storage space and memory, and downgrading the overall
performance of your computer. Several years ago most viruses spread primarily via floppy disk, but the Internet
has introduced new virus distribution mechanisms. With email now used as an
important business
communication tool, viruses are spreading faster than ever. Viruses
attached to email messages can infect an entire enterprise in a matter
of minutes, costing companies millions of dollars annually in productivity
loss
and
clean-up expenses. Most Viruses are written for, and affect Microsoft Windows machines. Generally,
there are three main classes of viruses:
- File infectors. These viruses attach themselves
to program files, usually selected .COM or .EXE
files. Some can infect any program for which execution
is requested, including .SYS, .OVL, .PRG, and .MNU
files. When the program is loaded, the virus is
loaded as well.
- System or boot-record infectors. These
viruses infect executable code found in certain
system areas on a disk. They attach to the DOS
boot sector on diskettes or the Master Boot Record
on hard disks. A typical scenario (familiar to
the author) is to receive a diskette from an innocent
source that contains a boot disk virus. When your
operating system is running, files on the diskette
can be read without triggering the boot disk virus.
However, if you leave the diskette in the drive,
and then turn the computer off or reload the operating
system, the computer will look first in your A
drive, find the diskette with its boot disk virus,
load it, and make it temporarily impossible to
use your hard disk. This is why you should make
sure you have a bootable floppy.
- Macro viruses. These are among the most
common viruses, and they tend to do the least damage.
Macro viruses infect your Microsoft Word application
and typically insert unwanted words or phrases.
How to protect yourself against viruses
The best protection against a virus is to know the origin of each program or
file you load into your computer. Since this is difficult, you should install
anti-virus software that typically checks all of your files periodically and
removes any viruses
that are found. For additional information, read the virus tips page
|
|
|
Learn how to protect your computer, surf safe, avoid scams, phishing exploits, and find security related software, all at our Computer Security Centre.
If you require professional assistance eradicating potentially
destructive viruses or malware from your system, simply call tech support at
905-685-1539 (select option 3) and make an appointment to
bring your computer in to
Vaxxine. For a modest fee, we will run a scan and rid your
machine of all virus files.
*Some limitations may apply
depending on the virus and amount of damage.
- Adware: Programs
that secretly gather personal information through
the Internet and relay it back to another computer,
generally for advertising purposes. This is often
accomplished by tracking information related
to Internet browser usage or habits. Adware can
be downloaded from Web sites (typically in shareware
or freeware), email messages, and instant messengers.
A user may unknowingly trigger adware by accepting
an End User License Agreement from a software
program linked to the adware.
- Dialers: Programs
that use a system, without your permission or
knowledge, to dial out through the Internet to
a 900 number or FTP site, typically to accrue
charges.
- Hack Tools: Tools
used by a hacker to gain unauthorized access
to your computer. One example of a hack tool
is a keystroke logger -- a program that tracks
and records individual keystrokes and can send
this information back to the hacker.
- Hoax: Usually
an email that gets mailed in chain letter fashion
describing some devastating, highly unlikely
type of virus. Hoaxes are detectable as having
no file attachment, no reference to a third party
who can validate the claim, and by the general
tone of the message.
- Joke Programs:
Programs that change or interrupt the normal
behavior of your computer, creating a general
distraction or nuisance. Harmless programs that
cause various benign activities to display on
your computer (for example, an unexpected screen
saver).
- Remote Access:
Programs that allow another computer to gain
information or to attack or alter your computer,
usually over the Internet. Remote access programs
detected in virus scans may be recognizable commercial
software, which are brought to the user's attention
during the scan.
- Spyware: Stand-alone
programs that can secretly monitor system activity.
These may detect passwords or other confidential
information and transmit them to another computer.
Spyware can be downloaded from Web sites (typically
in shareware or freeware), email messages, and
instant messengers. A user may unknowingly trigger
spyware by accepting an End User License Agreement
from a software program linked to the spyware.
- Trojan Horse:
A program that neither replicates nor copies
itself, but causes damage or compromises the
security of the computer. Typically, an individual
emails a Trojan Horse to you-it does not email
itself-and it may arrive in the form of a joke
program or software of some sort.
- Virus: A program
or code that replicates; that is, infects another
program, boot sector, partition sector, or document
that supports macros, by inserting itself or
attaching itself to that medium. Most viruses
only replicate, though, many do a large amount
of damage as well.
- Worm: A program
that makes copies of itself; for example, from
one disk drive to another, or by copying itself
using email or another transport mechanism. The
worm may do damage and compromise the security
of the computer. It may arrive in the form of
a joke program or software of some sort.
|
|
Contact Us