How Computer Viruses Travel by Email
Most people are trusting types, and they also don't expect to be tricked by others...and those two reasons are precisely why a lot of people actually do get tricked into spreading computer viruses.
One way computer viruses find their way onto computers is through emails or, specifically, attachments that are sent with an email.
A virus lurking in an email is like what you've see in old crime shows on TV, where someone receives a package in the mail and inside there's a bomb. Of course, the recipient doesn't know it—it's exciting getting a package in the mail—so they open it up. Kaboom.
A virus-loaded email is something like that. It will look like every other email you get, but inside there's danger in the form of a hidden computer program that will hurt your computer and/or steal data from you and others.
How viruses travel by email.
Here's an explanation of how a virus can end up spreading through your email, with your unwitting cooperation:
- You receive what seems to be an innocent-looking email from someone you know well (or at least know by name). The email will include an attachment that seems to go with the message of the email—if the message says something about a picture or video you have to see, the picture will have a name that seems to fit. If you open it up, you're on your way to trouble.
- If there's a virus hidden in that email, it's usually one of a few types:
- An attachment virus is a program attached to an email message, with a name that sounds intriguing. It pretends to be a photo or movie that you can watch right away. This is the most common type of virus.
- A Multipurpose Internet Mail Extension virus (called a MIME virus) takes advantage of a security gap in browsers or email programs. It's somewhat complicated—let's just say the bad guy overloads what's called the email "header" with information. The overflow information, instead of being discarded, goes into the memory to run programs. The virus program then gets run instead, unnoticed.
How the virus starts to spread.
Viruses come in different types and they can do different types of harm, but one thing they all have in common is that that reproduce or propagate.
A virus can go through your online address books, scan your old email files for names, or even look at your documents or spreadsheets to find names and email addresses to attack.
With those names in hand, the virus uses the captured email addresses to send copies of itself to your friends, colleagues and family—typically by using the same tricky email it used to fool you!
The email the virus sends looks as if it came from you...and may have some of the documents attached it stole from you. The email your friend receives might not even have YOUR name in the emails "From" section—it may have the name the virus took from your address book.
If your friends open the false email from "you," they've fallen victim and have helped the virus do its work. Thousands of people could be affected at one time.
Payload delivered. Damage done.
Once the virus has taken root, what happens next depends on the kind of virus that was spread. It might result in a threatening message, erased hard drives, frozen computers or corrupt files. None of it is good.
The damage delivered is known as the virus's payload, and it can hit right away, after a specific allotted time after delivery, or the virus may go off on all infected computers on a predetermined day and time.
So the next time you get an email with an attachment from a friend—and it seems perhaps just a little unusual—think twice before opening it.
By not opening it, you could be doing yourself and hundreds of others a huge favor.