Hello, and welcome to the 8th edition of Mouse Not Found!
More and more, these days, the topic of computer security crops up, with
discussions about viruses, trojans, firewalls and spam. In this edition of Mouse
Not Found I’ll try to explain a little more about what these words mean, how
they affect you, and what you can do to keep your data secure.
Viruses and Trojans
We’ve all heard of viruses, they infect our bodies and make us
ill, usually. Computer viruses work in a similar
fashion; they infect our computers, maybe corrupt our data (or worse), and pass
themselves on to other computers by some means. They are not organisms in the
same way as biological viruses, but they are small computer programs that are
cleverly written to hide in your operating system and affect its operation in
some way, whether benign or malevolent. They usually arrive unnoticed on our
computers as email attachments, or riding on the back of software downloaded
from the Internet or from floppy disk etc, and pass themselves on to others in a
similar way, often by emailing themselves to addresses found in the address-book
section or your email program. A variety of virus is known as a worm, the main
difference being that a worm is a self-propagating, self-contained program,
rather than a routine that attaches itself to existing files & programs.
Trojans take their name from legend - recall the famous wooden-horse that was
used by the Greeks to gain entry into the city of Troy (located in modern-day
Turkey), and thence to destroy the city from the inside. So a trojan, in the
computer sense, is similar, in that it is a program which installs itself on
your machine, and thereafter acts as a portal for unauthorized access to your
computer from the outside, i.e. the Internet, effectively bypassing any default
security systems. Trojans arrive by similar means to viruses, so detection and
prevention are achieved in a similar fashion, i.e. anti-virus software.
If you use your computer to receive email then you are at risk of catching a
virus, and unless suitable precautions are taken it is almost inevitable that
you will be infected at some point. The results of this could vary between a
mild annoyance, and total loss of data resulting in a complete re-install of
your operating system and software. The only solution is to purchase anti-virus
software such as Norton AntiVirus or McAfee VirusScan. These programs include
the ability to scan your computer for existing viruses (or trojans) on a regular
basis, and they also scan all programs that you run to make sure that they do
not contain a virus. But perhaps their most useful capability is the scanning of
all incoming email for viruses etc, since this is the primary medium by which
they propagate, and also the scanning of outgoing messages to prevent any
existing infestation from spreading to others. New viruses appear on an almost
daily basis, so to keep on top of the problem you need to ensure that your
anti-virus software has downloaded the most recent list of virus definitions.
This is normally an automatic process that occurs whenever you connect to the
Internet, and as part of the same update operation the software itself may also
be upgraded so that it can handle the latest types of problems. So the rules
are, (i) install good anti-virus software, and (ii) ensure the virus definitions
data is updated on a very regular basis.
Firewalls
Until fairly recently firewalls have been too expensive for
home computers, but this picture has rapidly changed with the advent of
always-on broadband Internet connections. A firewall is program that only allows
authorized data to pass through it, i.e. to enter or leave your computer. Its
purpose is to prevent your computer from being accessed by others via the
Internet while you’re connected, and also to prevent unauthorized programs like
trojans from sending data out across the Internet. One common problem today is
that innocent Internet surfers are having their computers used to forward on
mass-emails, or to launch hacking attacks on others. This can happen for example
when a trojan is present on your computer that allows someone out there on the
Internet to access your machine and use it as if it were theirs. The effect may
not be noticeable since your machine may be one of many that are being used to
achieve a bigger effect, but you are effectively masking the perpetrator of this
action, and it may be you who the attack is traced back to!
Obviously the people most at risk of the above are those that leave their
machines permanently connected to the Internet. If you are an infrequent visitor
to the Internet and switch your machine off after each session then its very
unlikely that you would be caught up in this sort of issues since your machine
would not be consistently visible to the Internet. Also, if you use a separate
router appliance running network address translation (NAT) then this will also
offer a good level of protection (if you don’t know whether your using a router,
then you probably aren’t!). If you do leave your computer permanently switched
on, and connected to the Internet, and you don’t use a router, then you should
seriously consider installing firewall software.
Fortunately there are a number of good firewalls available now at a very
reasonable price, or even free. Norton Personal Firewall (part of Norton
Internet Security product) is very effective, although rather complicated. A
good free offering is ZoneAlarm from Zone Labs, which is effective and simple to
use.
Spam
Although not a security issue, spam is nevertheless a big
problem which is still growing. Spam refers to unsolicited junk email that is
sent en-mass to large numbers of email addresses. Some spammers generate email
addresses at random in the hope of reaching new recipients, whilst others will
harvest addresses from websites, chatrooms, forums, or other spammers. It is
estimated that spam accounts for nearly 50% of email traffic today! There are
various forms of spam, some of which is pornographic in nature, and some is an
attempt to sell products designed to enhance your body in some manner. There are
also what are known as 419 emails, usually purporting to be from some
high-ranking Nigerian who wants you to help him transfer a large sum of money.
The term “419” derives from the section of the Nigerian criminal code that deals
with such problems.
Spam can only be countered by filtering emails, i.e. deleting any emails that
contain identifiable signatures like “buy Viagra online”, or come from known
dubious email addresses. Unfortunately the spammers have got wise to this, so
they disguise the content by breaking up words and replacing characters, e.g.
“buy V-1-a-g-r-a online”. Governments are now getting involved in resolving this
increasingly large problem, but hey, that’s the price we pay for freedom of
speech!
Links
I’ll close this article with a list of useful links relating
to the above issues:
Symantec Corporation: Norton AntiVirus, Norton Personal
Firewall:
www.symantec.co.uk
McAfee: VirusScan, Personal Firewall, SpamKiller:
uk.mcafee.com
