Protecting against email viruses

Most viruses are caught from emails, so this is where you need to take the greatest care. You must run a virus protection program if you use email regularly. You still won't be 100% secure, but 99% is better than zero.

Email viruses come in attachments that arrive with email. Sometimes the attachment is disguised so you can't tell what it is. Often it's from a colleague or friend whom you trust.

This happens because sophisticated viruses open personal address lists and send themselves on. The same thing can happen when you get a virus on your own machine - it can automatically mail itself to your friends.

Onward mailings are mainly a problem if you use Microsoft Outlook or Microsoft Outlook Express. For Webmail such as Yahoo Mail and Hotmail it's less of an issue - so far.

The best precaution you can take is to not open any attachment unless you're absolutely sure it's genuine.

I rarely open attachments unless I'm expecting them. There are dozens of unopened Word attachments in my mailbox. I used to think that picture attachments (JPEGs and GIFs) were safe, but virus makers have found ways to abuse the .jpg and .gif extensions, so these can no longer be trusted.

You even need to take care with mails from people you know well. Is the title of the mail out of character? Is the content unusually short, impersonal and otherwise bland and generic? All bad signs that this isn't genuine mail, but has been sent by a clever virus reading your friend's address book and automatically forwarding itself.

There are a couple of viruses (BubbleBoy and Kak) that infect your machine the moment you look at your mail, so if you're not running a virus checker and you've got Microsoft Explorer and Outlook you must download the Microsoft patch. Fortunately, these two viruses are relatively harmless.

There is one more virus that can download to your machine direct from an email or from a Web page, without presenting you with an attachment to open. This is the Nimda virus, which can do a fair amount of damage. If you are using Internet Explorer 5.0 or 5.1 you must install the Microsoft patch to keep Nimda out.

An introduction to viruses

Assess your risk

Read file extensions

Web downloads

Anti-virus software

In Microsoft Word documents