A computer virus is a program or script designed to cause damage to
your computer. Viruses will commonly corrupt files, multiply itself
into other files, or slowly delete all the files on your hard drive.
Some types can even steal your personal details, such as passwords or
even bank account details. The danger of viruses is that the damage
doesn’t stop when it infects you - it can also spread to other
computers that you send messages to, so your family, friends & work colleagues could also become
How to prevent and protect your computer:
Having antivirus software installed on your computer is an absolute
must, but make sure you keep the virus definitions up to date. New
viruses are always appearing, so your antivirus software should be
updated every day - in less than 24 hours your antivirus software
could be out of date and vulnerable to attack. In addition, scan your
computer’s hard drive in case a virus has found its way onto your
computer behind the scenes. The easiest way is to schedule an automatic
scan once or twice a week so you don’t need to manually run them
yourself. Antivirus software can also scan your computer while you surf
the internet and check the files you download before you open them.
A firewall is like a gate between your computer and the internet,
allowing certain things to go in and out. It provides an extra layer of
security by making sure you are aware of the potential consequences of
some actions you perform. For example, if you are accessing an
insecure network that is not recognised by your computer, the firewall
prompts you for permission before giving the connection the “all
The most common reason computers become infected with a virus is
because a user has clicked something without knowing what they are
opening. Viruses appear in two major areas, websites and email.
Websites are major targets for viruses, so never assume that a
website is safe, even if you have been sent a link to it by a friend.
The link may actually have been sent by an infected computer belonging
to a friend’s computer that has fallen victim to the virus. Often
website owners are unaware that their website is infected.
Sometimes while you are visiting a website, some pop-ups may appear
in the foreground. Pay careful attention to these, as clicking “yes” or
“ok” may cause a spyware program to be installed. Common places where
pop ups might appear are downloading websites, where it uses them as
advertisement, and often viruses can be placed on to one of them.
Be very cautious when you’re downloading files from the internet. Some things to keep in mind:
- If you are suspicious for whatever reason, it’s best to leave it.
- Have in your mind a realistic estimate of how big the file will
be, e.g. if you’re downloading a song, you would expect the file to be
around 4 - 8MB. If the file you are prompted to download is 100KB,
this should alert you that you may be downloading a virus.
- Check the file extension that your are downloading. Viruses
commonly use extensions such as .exe .com .bat .scr .pif and .vbs.
Files of these types are very suspicious.
These days it is not unusual to find that for every legitimate message in your inbox, you receive two spam messages. Being vigilant when
reading emails is absolutely critical.
Many spam emails contain a virus that comes lodged in an attachment.
These emails may also appear as though they are from a friend - just
because the email address is correct doesn't mean the email was
actually sent by a friend or family member. The sender may be unaware
that they have been infected, and that a virus is impersonating them to
try and spread it to you. Assure yourself by configuring your
antivirus software's email scanner to check your emails and
What to do if you notice a suspicious email in your inbox:
- If you don’t recognise the sender’s name, it helps to check
which domain the message was sent from. You can do this by hovering
your mouse over the sender’s name.
- The domain name is the part that comes after the @ symbol, e.g. “xtra.co.nz”.
- The last two letters of the domain tells you which country is from, e.g. “nz” = New Zealand.
- If the email is from a foreign domain, it is almost definitely spam and should not be opened.
- If it appears to be from a friend’s email address but
the subject is unusual or inconsistent, you can always ask the sender
first. You could send them an email, or better yet, talk face-to-face
- Never reply to emails that ask for your any of your personal or bank details - these are almost always a hoax.
- If you have already opened an email you think you shouldn’t
have, calmly delete the message. Don’t click on any hyperlinks in the
email or open attachments if there are any, including links that say