How to keep your PC healthy if
you use the Internet
What is the problem?
The
internet was invented by a bunch of geeks, for a bigger bunch of geeks to share
information. Geeks are inherently nice
to other geeks, so security was not considered, only the ability to have free
access to your fellow geek’s computer.
Now the
Internet is used by normal people instead of geeks. This means anything that can be stolen or
vandalised will be. (Makes
me want to be a geek!)
The biggest
problem is a computer virus. This is
just like the common cold. It finds a
little hole it can get into, and infects the host. It breeds, tries to
spread and survive as long as possible.
Originally viruses
just tried to put silly messages on your screen like ‘Ha Ha caught you!’. Then they thought
it might be funny to crash your system, and possibly wipe out all your
data. Now they want to try to steal your
credit card details or turn your computer into a slave to do their
bidding. Sending junk Email or
blackmailing corporates.
Viruses are
now used by big crime rings who blackmail websites. Imagine the loss of income to an online
betting service, if thousands of slave computers try to connect into the
service when a major sporting event is about to start. It’s like 10,000 people trying to get into a
betting office in your high street all at the same time. Not many of them are
going to make it! So the targets of this
scam pay up, rather than have tens of thousands of bogus connections come into
their machines. Your computer could be
one of those thousands, waiting to attack a big site.
How does my computer get infected?
A virus has
to be executed in order to try to infect you.
It can happen in a number of ways.
Traditionally
a virus would have come to you on a disk.
A program that you wanted to run would have already been infected, so
when you run the program it infects you.
The advice back then was, know the source of
any software you install and only install original (not copied) software. The advice is still correct, but rarely
taken!
With the
wide adoption of email, viruses found a new way of spreading. An email on it’s own
is fairly harmless, but combined with the ability to ‘attach’ files, email
suddenly became the main vehicle for virus infections. The virus would always be in an attachment,
and virus writers would use all sorts of incentives for you to open an
attachment. Statements such as ‘someone
loves you, open the attachment to find out who’, or ‘Re:Your Order, information in the attachment’. One of the best is ‘your internet account is
going to be cut off unless you follow the instructions in this attachment’. Many people are fooled by that one.
Other good
scams are;
“This is
technical support from XYZ. You need to
reactivate your account by clicking here.”
“This is
technical support from XYZ. Your
computer has a problem, fix it by clicking here.”
“This is
technical support from XYZ. You are
exposed to a virus, fix it by clicking here.”
“This is
your Bank, you need to re-confirm your credit card
details to keep your account open. Enter
them on the form obtained by clicking here.”
“This is Ebay, due
to loss of data we need you to confirm your account details on the next page.”
Be warned,
these scams will look very authentic. They
steal graphics from the people they are impersonating, and take absolutely no
notice of the ‘From’ address. This is
totally unreliable, almost as easy to change as the subject line on the email. If you want an email from Elisabeth.windsor@thepalace.windsor.uk,
I can send you one. The bottom line here
is don’t click on something in an email, and then go
typing personal info. If your bank, or Ebay, loose your data, they
are going to be closing real soon. (I
know what Ebay use internally,
they won’t be loosing your data.) I have
had one of these mails from support@barclays.com
asking me to enter my details again for some reason. Guess what – I don’t have an account with
Barclays.
To avoid
catching a virus from an attachment, the best advice is not to open attachments
from anyone, even people you know, unless you are convinced that they intended
you to receive and open the attachment.
The reason this is phrased as it is, is because of the following issue…
If I caught
a virus (of this sort) the first thing it is going to do is send all my
contacts a copy of itself. So you receive an email from myself,
asking you to look at the attachment.
You see it’s from me, so you open it.
It’s not from me, it’s from a virus on my system, and you have it too
now!
So what was
the statement earlier? “unless you are convinced that they intended you to receive and
open the attachment” How can you be
convinced, or convince someone that the message is from you, and not your pet
virus? The answer is to include some
personal references that a virus does not know.
Mention hobbies, the kid’s names, anything that a virus could not
possibly know about you our the person at the other
end of the email.
If the
message says ‘this is from your chubby friend in
The last
way to catch a virus is the most scary, because all you have to do now days is
connect to the internet!
This is a
chapter on it’s own…
Catching a virus by going online…
When you
connect to the internet, you are assigned a unique number (a bit like a
telephone number) and this is how you are identified whilst online. There are 4228250625 numbers (but not all are
available).
Most of the
computers that go online use Microsoft Windows as their base software, and this
is where the problem starts.
Windows is
such a hugely complex product (beyond most peoples comprehension) that many
faults are not discovered until the product is in the market. If we are lucky Microsoft releases a fix for
each of the faults. These fixes are
available online for download.
Many of
these faults are gaping holes in the security in Windows that would allow a
virus into your system.
Often a
virus author will look at the updates from Microsoft for information. On the basis that people DON’T read articles like
this one, and take the enclosed advice.
So, the list of fixed faults from Microsoft is a list of all the ways into your computer.
The virus
author then writes something that will choose one of the 4228250625 possible
addresses on the internet, guessing that there is a vulnerable Windows machine
there, and tries to break in using the information that Microsoft so kindly
provided. If you have not blocked the
way in, you are infected with the virus, and it then starts again on your
machine, sending itself to any of the 4228250625 addresses it fancies.
So in no
time at all, almost all of the 4228250625 addresses have been ‘tried’ and
anyone who doesn’t have the patch, has the virus. And they all wait for their ‘next
instruction’. Attack a website by trying
to connect at the same time? Wipe out
your data? Send your credit card data to
a crime ring?
What can be done about it?
The clues
are already there!
Microsoft
put out a fix for a problem they have identified. You don’t adopt the fix. You catch a virus.
Can you see
how easily this changes to…
Microsoft
put out a fix for a problem they have identified. You adopt the fix. You don’t catch a virus.
Also you
should buy anti-virus software and keep it updated (in the same way as keeping
Windows updated).
Anti-virus
software is out of date when they press the CDs. New viruses come out so often that out of
date anti-virus software is useless.
How do I keep updated?
You are
going to wish you had looked and not asked!
On the
start menu of Windows is an option “Windows Update” – start this off, accept
anything it asks you and let it download and install any patches it offers. More details on using Windows Update can be found here.
I use
Norton Anti-virus and can only report on how to keep this updated. I guess other anti-virus software is the
same. Click the “Live Update” button
within Norton Antivirus. More details on using Norton
Anti-virus Live Update can be found here.
So it was
simple really.
Both
Windows and NAV can be set up to automatically download updates, but Windows
will only get the ‘critical’ updates, so I suggest you check manually on
occasion, even if you have selected automatic updating.
Possible Issues
Too many
updates – if your computer has been in to me for maintenance, I will have
suggested you let me get it up to date will all the patches. This is simply because my broadband
connection is 20 times faster than a modem connection. Windows XP has over 100 updates available,
these take about a day to download on my broadband connection, so you are
looking at about 20 days if you are on a modem.
If you had
just installed Windows XP with no patches, you are more likely to win the
lottery than get all the 100+ patches for XP installed BEFORE one of the
viruses gets you.
So if you
are behind on your patching, get some help.
Other options
One way to
stop the ‘third category’ virus infections is with a firewall. The phrase comes from the forestry practice
of keeping a break between sections of forest, so that a fire in one section
cannot make it across to another area.
A computer
firewall is like a bouncer at a nightclub.
Without an invite you don’t get in.
Information
from the internet normally comes in, because you have asked for it. You have given it an invitation to show the
bouncer (if you have one). But an
attempt to plant a virus on you via one of the Microsoft holes comes in without
an invite, so a firewall stops it.
It won’t stop
a virus that’s in an email attachment, as you asked for the email to be
fetched, thereby inviting it in.
A firewall
is normally another computer, and NOT running Windows.
It is
possible to run Firewall software on the machine you are trying to protect. This I am not convinced about. How much use is your nightclub bouncer if
he’s sitting at the bar instead of outside at the door? As the issue is that Windows is as secure as
a sponge, how much can you do building on that base?
If you are
technical and interested in firewalls, I use packet filtering and NAT on OpenBSD. It’s free,
runs on hardware that you would otherwise be throwing away, and OpenBSD is audited line by line for security holes. Is there another operating system that can
make that claim? All silent in Redwood
are we? (IT Joke!)
That’s the
other reason I can load your system will all 100+ of XP patches in a day, and
without catching an infection, because I have a physical separate machine
running as a firewall.