What is a Virus (or a Worm or a Trojan)?
All of these can be called Malware, or Malicious software.
A virus is a computer program or code that replicates itself and infects
another program, boot sector, partition sector, or document that supports
macros, by inserting itself or attaching itself.
A worm is a program that copies itself from one disk to another by e-mail
or other transport mechanism. Worms infect computers, but do not infect
files. They can simply be identified and then deleted. However, they often
make registry or startup file changes so that they are executed on
boot-up. They are now very sophisticated, can avoid detection by antivirus
programs and even disable them (and firewalls), so that you may have no
protection whatsoever. It is probable that a lot of spam is sent out from
such infected computers, unknown to the owner of the machine.
A trojan is a program that neither replicates nor copies itself; it may
arrive in an e-mail, in a program, or by simply viewing a web page (if
your browser has an unpatched vulnerability). It can be commanded to do
tasks such as sending information away from your computer, or it may open
a "back door" which allows a remote computer to control your machine.
Spyware is sometimes planted in your computer without your knowledge or
permission when you install a new program or while you are connected to
dialler may redirect your dialup connection to a remote destination and
you will be charged for the phone call. See
All must be regarded as harmful, though some viruses and worms are not.
Why should you be concerned about
Because you are likely to be infected at some time, especially if you take
no precautions. See:
Although your ISP may have a virus scanner for e-mail, some viruses may
slip through. You can also be infected from other sources such as some
Internet sites (Web surfing), removable media (floppy disks, CD-ROMS etc),
and Internet messaging (Windows Messaging, IRC etc) or file-sharing (via
Internet or internal network).
Infection with a virus may result in great inconvenience, the possible
loss of some of your data and programs, revelation of your private
information (including passwords and credit card numbers), or even
destruction of your system.
You may also spread the infection to many other users via addresses stored
on your computer, or in files you share with others. Your computer could
be taken over and made a base for attacks on others. Therefore, it is in
everybody's interest for you to be informed about how viruses spread, and
ways to avoid and control them. And it is important to recognise a Hoax
for what it is, so as not to be panicked into unnecessary action.
How will I know if I have a virus?
You may be alerted by other persons who believe you have sent them a
virus. This may not be true, because Melb PC and other ISPs scan mail for
viruses, and many viruses use false "from" addresses which are randomly
selected or generated. The message bearing the virus most likely came from
a computer on which your address is recorded, but you should check your
Or you may be alerted by your antivirus software, if installed. Exactly
what message did your anti-virus software give you? Write this down before
you click the "OK" button that dismisses the warning.
You may be alarmed! because your computer is behaving abnormally - can’t
open some programs, strange things happening, it locks up, or won’t start.
But do not assume a virus is responsible for any computer problem that may
be readily and simply fixed. And note that even if some odd system
behaviour is due to a virus, the "three R" solution (re-partition,
reformat and reinstall) is seldom necessary or appropriate.
You may also get a False Alarm in the form of a Joke or a Hoax. False
alarms can be more time-consuming and wasteful than actual virus detection
incidents. Hoaxes come in e-mail messages or attachments, are often in
bold or capital letters, offer exciting rewards, or warn you to do
something to prevent some catastrophe. They may be harmless, but can cause
a lot of trouble if you follow their instructions. Do not forward any such
warning message to all your contacts without verification. A good website
to check if it is a Hoax is:
How could I have got a virus when
I have antivirus protection installed?
Your AntiVirus program may not be up-to-date, or more likely your
operating system and browser have not had the latest "patches" installed.
This is particularly important when upgrading to or reinstalling a new
operating system, after which you are vulnerable until you have installed
the patches to bring it up to date.
You may have taken the precaution of installing AntiVirus software, but
lapsed in keeping it and your operating system updated. To be effective,
antivirus software should have been updated within the last week at least,
best within the last 24 hours. Or you may have been unlucky enough to
acquire one of the latest new viruses, for which a signature update has
not yet been prepared (it takes at least a few hours for new virus threats
to be countered, and for your software company to offer a "fix"). Download
and install the latest update when it becomes available, then do a full
scan of your system.
What should I do if I have a virus?
Help is available if you ask for it . Always contact your Antivirus
software vendor first, or look for advice on their webpage if you can.
Contact Melb PC Internet Help by telephoning the First Aid (Help) line
(95678066, 10 am to 3pm) or the Melb PC office (95678000) to avoid using
your computer. But read on, to help yourself.
What can I do to protect my computer from viruses?
- Avoid using your computer,
especially to go online, until the virus is "cleaned". Most viruses are
transmitted by e-mail, but by simply connecting to the MelbPC Intranet or
the Internet you can be sending copies of the virus out of your computer.
The virus usually has its own means of sending mail out even when you are
not accessing your email account. So, only connect to the Net if you have
to, for example, to get help, or to obtain an Update or Patch for your
operating system, or to update your AntiVirus Program (subsequently
referred to here as AVP, see below). And make sure our Firewall is active
if you do need to connect, especially for updates to Windows XP. Then
disconnect till your computer is cleaned.
- If you have an Anti-Virus Program (AVP) -
Check that it is up to date. This means it has been updated within the last
week at least, best within the last 24 hours. If it is not up to date (and
it probably is not if you have acquired a virus), then do so at once. Then
do a full scan of all your hard disks. This means that the scan includes
boot sectors, memory, and files of all types,including those in subfolders.
Most AVPs are set to do this by default, after a Typical or Standard
intallation, but you should check the configuration if you feel capable.
Try the toolbar of the program, possibly under Options.
It is unwise to scan for viruses with an out-of-date AVP because the
program must open the files to scan them. If the AVP cannot recognise or
destroy the virus(es) it may release or activate some that have until that
time been dormant.
If you have taken the precaution of installing anti-virus software, but
have had a temporary lapse in its maintenance, it will be easier to recover
from a virus infection.
Likewise, if you were unlucky enough to have acquired the very latest virus
for which a signature update has not yet been prepared, it will be simpler
and quicker to download and install the latest update when it becomes
available than to start from scratch.
All AVPs, and particularly updates, must be obtained from a reliable
- If you do not have an AVP -
Ask for help from Melb PC (see above), or buy a commercial AVP, online or on CD-ROM, or
download a free AVP from http://www.free-av.com/ or
Note that a free program may be less useful than one you pay for, e.g. you
may not get telephone support, or updates may be less frequent. And you may
sooner or later be required to pay for it.
The AVP you obtain may be a few months old. It is unwise to scan for
viruses with an out-of-date AVP because the program must open the files to
scan them. If the AVP cannot recognise or destroy the virus(es) it may
release or activate some that have until that time been dormant. It must
be updated to be effective. This must be done online before you (next)
Do a full scan on all your hard disks (see 2 above).
The scan should report that the virus has been cleaned, deleted,
quarantined or neutralised. It may also tell you if some elements could
not be removed, or that the scan was incomplete (e.g.,unable to scan .zip,
.cab,or .dat files).
- If your computer will not start, and you have a Rescue Diskette created
when you installed your AVP, this might be the time to use it, but you will
need to know what to do. If you are not sure, try contacting your AVP
support line first. If you do not have a Rescue disk, you may be able to
recover with a bootable Startup disk, plus appropriate advice. Occasionally
a virus will need to be removed in Windows Safe Mode, or by booting into
DOS (and use an AVP for DOS), because it can escape detection and removal
when Windows is started in the usual way.
- Transmission of the virus
In most cases, the virus/worm selects addresses in your address book and
message folders, and even anywhere on your hard disks, to which it send
copies of itself by e-mail. It is not practicable to hide or delete these
addresses, and most viruses/worms make up false ones anyway! So the best
you can do is to avoid going online, or to minimise the length of time you
stay connected to the Net until the virus has been cleaned.
- AVPs cannot eradicate all viruses completely. While the Internet Help (iHelp) team will give whatever help they can,
expert help may be required from the AVP vendor by telephone, or from their
website. Some viruses, by their nature, cannot be "cleaned". They may have
created new files which remain on your system (residual files), and these
may need to be removed manually (including editing the Windows Registry),
or require a Removal Tool. They may also have renamed, altered or deleted
some files. This may require reinstallation from original or backup copies
of your software. Occasionally a virus will need to be removed in Windows
Safe Mode, or by booting into DOS (and use an AVP for DOS), because it can
escape detection and removal when Windows is started in the usual way.
- Change your passwords.
Some types of malware steal your passwords and other information, sending
it away to a remote site. So it is advisable to change passwords and to
review all security settings after recovering from a virus attack. It is
good practice to change your passwords periodically.
The most important things are
- to install good AntiVirus software (see What anti-virus programs are
recommended? for a list), and to keep it constantly updated,
- to update your operating system and browser, which for almost everyone
is Windows and Internet Explorer (see Internet Explorer Updates and Windows
Updates, below), and
- to install, activate, and properly configure a Firewall
Operating System and Internet Explorer Updates -
Some e-mail programs are particularly targeted by virus writers, e.g.
Outlook and Outlook Express. These are vulnerable because of their
association with Internet Explorer. When you look at an HTML message in the
preview pane or open message window you're actually looking at a browser
window. So any vulnerability of Internet Explorer is 'inherited' by the
email program. because of Internet Explorer's close integration with
Windows. Internet Explorer can be "patched", but if you don’t install the
patches, simply changing to Netscape, Opera, Eudora, or The Bat as your
e-mail client will not protect you if you retain the vulnerable copies of
Internet Explorer on your computer. Most users do not try to uninstall
Internet Explorer completely (though it is possible), so the recommended
updates and patches should be installed, otherwise the susceptibility
remains. Currently it is recommended to upgrade to Internet Explorer 6.x
for later versions of the Windows operating system (it cannot be installed
with Windows 95). You can have it installed and still use a different
browser or e-mail client if preferred.
The IE 6 installation from the Web should be Typical or Full, not Minimal
or Custom, or preferably, install it from a Melb PC Monthly CD-ROM which is quicker and
All versions of Internet Explorer require updates or patches. Many members
will be using IE 6.0 with Windows 98. Updates for these
versions are now hard to find!
Get updates for later versions via Windows Update (Go to Windows Update
from Internet Explorer | Tools menu and follow the prompts), which can be
configured to update automatically (see below), or accessed via these
You are advised to install "Critical" Updates for Internet Explorer and for
your version of Windows.
Read the information shown to decide whether to install "Recommended"
Automatic Windows Updates need Microsoft Internet Explorer. To set up
automatic Windows Update:
See http://support.intel.com/support/network/sb/CS-010266.htm for all
Windows OS versions
and http://www.theeldergeek.com/automatic_updates.htm for Windows XP only.
What antivirus programs are recommended?
Can I get a free antivirus program?
This is a matter of personal preference, as all the well-known programs
are effective. A Web search will lead to information and download sites.
Here is a list which is not comprehensive, and is in alphabetical order
and not necessarily by recommendation :
Yes, but note that a free program may be less useful than one you pay
for, e.g. you may not get telephone support, or updates may be less
frequent. Or you may sooner or later be required to pay for it. Note that
after installing the program it is necessary to update it regularly.
Will I be completely protected if I install an antivirus program?
- AntiVir Personal Edition is available from
- AVG Personal Edition, from
- Avast! 4 Personal Edition available from
No, because no anti-virus checker can be said to be 100% effective,
even if it is frequently updated. There is a constant battle between virus
writers and virus eradicators, and variants may appear when the code is
altered slightly. New viruses are appearing all the time, and may infect
some computers before a "fix" is written for them. And an AVP will not
help if your operating system is not "patched" up to date.
It would be wise to adopt "defensive computing" practices, see Defensive
Even if your ISP (e.g., Melb PC) provides virus scanning on your Internet
connection, a virus may occasionally slip through, so it is important to
have your own virus protection. There are other sources of infection also.
Are there any software programs that are immune from virus attack?
The answer to this has to be "No", but virus creators tend to
concentrate their efforts on the programs that are most widely used, so
that the virus spreads easily and has maximum effect-usually damaging! It
is true that some are less likely to be attacked, or less vulnerable.
But see How can I protect my computer from viruses? for an explanation of
major weaknesses, and Defensive Computing (below).
Are there any software programs that are immune from virus attack?
The answer to this has to be "No", but virus creators tend to concentrate
their efforts on the programs that are most widely used, so that the virus
spreads easily and has maximum effect-usually damaging! It is true that
some are less likely to be attacked, or less vulnerable. But see How
can I protect my computer from viruses? for an explanation of major
weaknesses, and Defensive Computing (below).
Defensive Computing (Other precautions you can take)
Networks and Passwords
- Never open attachments to e-mails (even from an
apparently trusted source, because the "From" address can be faked, called
"phishing") or never open without first scanning them with an up-to-date Anti-Virus
Your anti-virus software may be set to do it by default, but you can do it
manually to be sure. You may choose to open only those attachments which
you have asked someone to send to you (and you should scan them too).
Regard all unsolicited mail and forwarded messages (even if forwarded from
someone you know) as suspicious. Beware of persuasive messages with
strange headings, or invitations that promise rewards or excitement. For
image files, open the viewing application (e.g., Irfanview) first and open
the pictures in it, instead of double-clicking on the attachment. Don't
trust the icons or file extensions on attachments; they may be
deliberately falsified to mislead you into opening a file which seems
harmless. Try to get all attached documents sent to you in Rich Text
Format (*.rtf), or do not enable macros in Word.
- Show all file extensions Configure Windows to always show file extensions. From Windows Explorer |
Tools | Folder Options, uncheck "Hide file extensions for known file
types". Then it will not be possible for an EXE or VBS file to masquerade
as a TXT or JPG file. And never open attachments with extensions VBS, SHS,
or PIF, which are almost never used in normal attachments. Also, do not
open attachments with double file extensions, like NUDE.JPG.EXE or
Microsoft NEVER DISPLAYS .shs, .pif, and .lnk file extensions, whether you
have hide file extensions on or off. Therefore, as further protection for
Melb PC members, all attached files with extensions as above (plus .scr for
good measure) passing through the Melb PC virus checker will be renamed
with an underscore replacing the first letter of the extension. With the
underscore, they are no longer executable under Windows unless the missing
letter is replaced (at your own risk!).
Other Executable files (e.g., .exe, .htm,.html) may also have a double
extension (.bad) added . You may try renaming them as .txt and opening
them in a text editor like Notepad, or you can restore the executable
extension as above.
The attachments are unchanged otherwise.
- Disabling the Preview pane In Outlook and Outlook Express, “Auto preview” and “Preview” respectively
can allow activation of a virus in a message being viewed in the pane (see
explanation under IE Updates "What can I do...?" above). In other words,
if the message is highlighted, (one message in the list always is), it
will open in the Preview Pane without being clicked. This is a useful
feature that many do not want to disable.
It need not be disabled if the appropriate updates have been installed,
and your Anti-Virus Program is kept up to date.
To disable the Preview pane (esp.for users of Windows 95):
- In Outlook Express 97, from View|Layout|remove tick from “Show preview
- In Outlook 97, from View|Define views|Tick “messages” and not “messages
- Previewing your mail on the mail server
You can avoid having to download your mail before you read it (and this is
also one way of disposing of Spam mail) by using programs such as MailWasher which also allows you to set bounceback criteria
"for lists where unsubscribe proves difficult". But don't use it to bounce
SPAM; this is quite ineffective as many "from" addresses are fictitious,
and you will merely increase traffic on the Internet (and specifically on
our Internet feed), with messages either returning to the wrong address,
or being marked undeliverable, and returned. MailWasher works with all
email programs unless they are Web based such as Hotmail, Yahoo and AOL.
Mailwasher can be found as a free download at:
Mailwasher Pro with increased functionality is available at:
- Or you can use to MelbPC Endymion Webmail in 2 ways:
1. Or via the External Home Page (http://www.melbpc.org.au and then
2. In your browser address bar enter URL:
(a secure connection)
Then enter your username and password and "login". Here, you can see the
size of your mailbox, read, send, and delete messages, but you cannot
download them to your computer.
- Review Security Settings In Internet Explorer, these should be set at "Internet", in Tools |
Internet Options | Security, and Custom Level should be "Medium". In
Outlook Express, from Tools | Options | Security set the level to
"Restricted Sites Zone", and tick "Warn me if other applications try to
send mail as me". Do not tick "Do not allow attachments to be saved or
opened that could potentially be a virus" unless you DO NOT have an
up-to-date antivirus program, because if you do, some attachments which do
not contain viruses (but are regarded by Outlook Express as potentially
harmful), may be barred.
This is a view of Security Settings opened in Internet Explorer via
- Other sources of infection Be Aware that other viruses can reach you via infected files in floppy
disks or CD-ROMs, in files downloaded from the Internet (including
newsgroups), or exchanged via IRC, ICQ, etc. (for example, see:
and by simply browsing some Web pages or clicking on innocent-looking
messsages. This may include reading messages in Hotmail, Yahoo Mail, and
AOL, though email scanning is now very effective. So an up-to-date
Operating Syatem and AVP with “Resident” protection are essential.
As a general rule, when in doubt never click "OK" or "Close", rather
"kill" the dialogue box with the "X" in the top right-hand corner.
If you have a Floppy Disk drive it is also recommended to set the startup
sequence in the BIOS to C:A:, CD-ROM, C:A:, or just C:(or HDD) to prevent
inadvertent booting from a floppy disk infected with a boot virus left in
the drive. In the event that you need to boot from A:, you will need to
reset the BIOS by entering Setup during the bootup process.
Resident Protection should be enabled in your AntiVirus program
This is AntiVirus protection which is activated when the computer is
started, and then remains "on watch" in the background. It may also be
called by other names, e.g. Real-Time Monitoring. Most Resident programs
will watch for executable file types, detecting them when they are
downloaded or copied, or when a file is opened. Some programs, but not
all, scan e-mail messages also (usually only incoming messages, by
default). But many viruses are programmed to disable AVPs.
Any AVP installed on your computer is useless if it is inactivated.
Sometimes the AVP may be disabled to prevent it interfering with another
program, e.g. while running Windows Defrag, or it may be turned off while
installing a new software program, and you may forget to turn it on again.
Check that Resident Protection is enabled, usually by right-clicking the
AVP icon in the "Tray" at the lower right hand corner of your computer
screen, and selecting "Status" or a similar option, or by opening the
program and checking (usually) Options.
You can be test your system for virus infection with free scanning
NOTE: these URLs MUST be in ONE LINE if copied or typed - or use the main
site address and then navigate from there.
If you are connected to a network and have file-sharing enabled, important
files should be password-protected. Viruses spread very easily and quickly
on networks. Passwords should be jealously guarded, and changed
periodically, particularly after a virus attack. If your operating
system has Administrator or Root privileges, login as a User instead of as
Administrator, Superuser or Root. This will protect most of your files
from being tampered with
Another line of defence is a firewall. These have become more necessary,
even essential, as malware becomes more sophisticated. A firewall is
strongly recommended if you are connected to your ISP by broadband (cable
or ADSL) which, unlike Dialup connections, is "always on". Windows
XP and XP Pro have an inbuilt firewall . It may not be enabled by default.
To see if it is enabled go to Control Panel>Network
Connections>Properties>Advanced and make sure the tick is in place under
"Internet Connection Firewall", or see
http://www.thundercloud.net/infoave/tips/firewall/ for full
is one in common use, but it is important to understand its actions and
Kerio Personal Firewall (
http://www.kerio.com/kpf_home.html) is another, see
A firewall will block access to your computer from the Internet, and can
also prevent information being sent away without your knowledge, depending
on the instructions you give it. For either Resident protection or a
firewall to be effective and trouble-free, each must be properly
configured. Read the instructions carefully.
Firewalls should be tested to see if they are effective. Go to "Shields
Up" at http://www.grc.com/ or direct to
Subscribe to a (Free) AntiVirus Newsletter
Stay informed! This will get you virus alerts, details of new viruses and
hoaxes, tips, and much useful information. This includes descriptions of
how to recognise suspicious mail headers and message wording. From any of
the major AntiVirus program vendors, e.g.,
Visits to their websites will also yield much useful information, e.g.,
, http://www.europe.f-secure.com/v-descs/ or
Virus alerts and detailed information on new viruses can be found on the
MOTD page by clicking the "Latest Virus Advisory" link at: