What is a Trojan horse program?
A type of program that is often confused with viruses is a
program. This is not a virus, but simply a program (often harmful)
pretends to be something else.
For example, you might download what you think is a new game; but when
run it, it deletes files on your hard drive. Or the third time you
the game, the program E-mails your saved passwords to another person.
Note: simply downloading a file to your computer won't
activate a virus or
Trojan horse; you have to execute the code in the file to trigger it.
could mean running a program file, or opening a Word/Excel document in a
program (such as Word or Excel) that can execute any macros in the document.
You can't get a virus just by reading a plain-text E-mail message or Usenet
post. What you have to watch out for are encoded messages containing
that include an executable file attachment (i.e., an encoded program file or
a Word document containing macros).
In order to activate a virus or Trojan horse program, your computer has to
execute some type of code. This could be a program attached to an
Word document you downloaded from the Internet, or something received on a
floppy disk. There's no special hazard in files attached to Usenet
E-mail messages: they're no more dangerous than any other file.
Treat any file attachments that might contain executable code as carefully
as you would any other new files: save the attachment to disk and then check
it with an up-to-date virus scanner before opening the file.
If your E-mail or news software has the ability to automatically execute
to a message, I strongly recommend that you disable this feature.
My personal feeling is that if an executable file shows up unexpectedly
attached to an E-mail, you should delete it unless you can positively
verify what it is, who it came from, and why it was sent to you.
The recent outbreak of the Melissa virus was a vivid demonstration of the
need to be extremely careful when you receive E-mail with attached files or
documents. Just because an E-mail appears to come from someone you
this does NOT mean the file is safe or that the supposed sender had anything
to do with it.