Identifying Malicious Software
How do you know when your computer has been invaded by hostile software? The worst way to find out is to install an antivirus program, scan your computer for the first time, and discover that you've been infected for who knows how long. In the case of a Trojan horse program or a virus that disables your antivirus protection, you might not have any clear-cut warning. In those cases, you must be alert for changes in the behavior of your computer that could indicate the presence of a virus or a Trojan horse program.
Don't be fooled by forged addresses
If you receive a frantic message from a friend or business associate complaining that they've just received an e-mail message with an infected attachment from your computer, ...