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Protecting
Yourself from Viruses
Background
Information
The main way that computer viruses are
spread today is via email. More
specifically, email attachments. New viruses are being created and
released continually and the updates for the anti-virus software will always
lag behind the release of new virus. As a result there is always some
window of opportunity for your computer to become infected if you only rely
on anti-virus software to protect your computer.
Tactics
used by Viruses/Worms
Self
contained mail transfer program Most
of the newer viruses/worms use their own basic email program and not your
actual email program. This way they can easily, and continuously send
out copies of itself without the need to access your email program. Once
a computer is infected, the virus/worm searches your computer for email
addresses it can use. It will search for various address book files as
well as email addresses located within documents on your computer. It
will then send itself out to these addresses, as well as variants of the
addresses it finds. For example, if it finds the address abc@company.com
it will use that address plus it will guess at other addresses at company.com
by using popular user IDs, and send out messages to address like
sue, joe, bob, and jim@company.com. Spoofing
Sender Information These
viruses/worms also pick, at random, one of the addresses it finds and uses
that address as the sender address. So when you get an infected email
and it says it came from Jane Doe; in reality it was sent from John Doe's
infected computer. Jane Doe just had the misfortune of having her email
address on John
Doe's computer along with you. This accounts for
the automated messages you receive from email systems stating
that the message you sent could not be delivered because it contained a virus.
For example; If a virus/worm had used your address as the sender address when it sent itself
out from an infected computer, the recipient's email system identifies
the infected email and since it has your email address in the from field the
recipient's mail system sends you a reply stating
that you had sent an infected email. When it actuality it had come from
some other computer. Another
interesting situation that arises with these new viruses/worms is that you can
receive a message to you that was from you, yet you never sent the
message. In this case it's a dead giveaway that it's not legitimate and
should be deleted.
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Protecting
Yourself from Viruses
Basic
Guidelines
The best
means of protecting your computer from viruses is to use extreme caution
when handling email attachments. If it looks somewhat suspicious, it
probably is. A good rule of thumb is not to open attachments unless
it is something that you've been expecting. Even if the email
appears to have come from someone you know and trust don't open the attachments
unless you've been expecting them. If you think that the attachment
might be legitimate but were not expecting it, you can always call, or
send the "sender" an email asking them if they actually sent you
something. It's always better to be safe than sorry.
Viruses
and GroupWise
GroupWise
Quick Viewer
While there
have been viruses/worms that have exploited aspects of the preview
pane in Microsoft Outlook products; there should
be no concern in using the GroupWise Quick Viewer as it doesn't use the
technology that's being exploited.
Access
Denied messages when opening email in GroupWise
Note:
The following only applies when you are opening messages in GroupWise!
It may, or may not apply in other circumstances!
There are a
few circumstances (not many) when GroupWise will attempt to write the attached files of a
message to a temporary location on your computer when you
open an email message. If the attachment is infected with known
virus
McAfee will prevent the file from being written to your computer and
inform you by popping up an "access has been denied" window. If this
happens do not be concerned. Just click the stop button twice to get
rid of the access denied window and then delete the offending email.
If the attachment is infected with an unknown virus, McAfee will allow the
file to the temporary directory but is not executed until initiated by the
user. So as long as you don't execute the attachment your computer
will not get infected. The temporary files written to your
computer are automatically deleted once you close the originating email.
Need
More Help
If
you're on the BFS network and have any further questions or concerns
please contact the Systems Help Desk at x4582 or help@bfs.uwm.edu.
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