Recognizing and Detecting Viruses

Email messages with attachments may seem entertaining and harmless... but don't be fooled!

Viruses are commonly spread through email attachments. All it takes is one mouse click to launch a virus that may potentially send itself to everyone in your address book or destroy all of the data on your hard drive.

You can avoid a virus infection if you exercise reasonable caution when opening email attachments. There are some distinct characteristics that can help you identify a virus before you become infected by it. Look out for the following:
  • Email attachments that come from someone you don't know
  • Email attachments that you aren't expecting
  • An email with an attachment, but no subject line and/or text message explaining what the attachment is
  • Duplicate emails from the same person - you may receive one valid message with text, followed immediately by a second email with no text, just an attachment
  • Multiple identical email messages from the same person that arrive in your inbox within a few seconds of each other
  • Any email attachment with an '.exe' file extension - for example: whatever.exe or sample.exe
  • Any email attachment with two file extentions - for example: resume.doc.pif or Love-letter-for-you.txt.vbs
  • Any email attachment with these file extensions: .bat, .reg, .scr, .dll, or .pif
  • Any email or attachment that asks you to delete files from your hard drive

If you receive an email attachment that fits any of the above criteria, don't open it! Either delete it right away, or reply to the sender and ask for more information to find out if it is truly legitimate.

Rule of Thumb: If there are any doubts about an email or an attachment, delete it immediately! Other ways that viruses can spread:
  • File sharing and Network Neighborhood - If you have file sharing turned on with write permission, you can become infected with a virus. Marking your shared files and directories as 'read-only' can reduce this risk.
  • Floppy disks - Files such as Word documents can become infected with viruses. If you've saved an infected file to a floppy disk and used the disk in other computers, you can potentially infect those other computers with the virus. Borrowing disk from other people also puts you at risk for virus infection.
  • Web pages - If the server that hosts a website is infected with a virus, you can potentially contract the virus by visiting that site (this is rare).
  • Downloading software - If the file you are downloading, or the server you are downloading it from is infected with a virus, you can potentially contract the virus by downloading and installing that file.
  • Instant Messaging, IRC, ICQ - Anytime you accept a file from someone over a network, you are at risk for virus infection, especially if your client software is set to automatically accept files or to automatically run files that you've accepted.