What is a computer virus?

As defined by Microsoft, computer viruses are small software programs that are designed to spread from one computer to another and to interfere with computer operation. A virus might corrupt or delete data on your computer, use your e-mail program to spread itself to other computers, or even erase everything on your hard disk.

Computer viruses are often spread by attachments in e-mail messages or instant messaging messages. That is why it is essential that you never open e-mail attachments unless you know who it's from and you are expecting it. Viruses can be disguised as attachments of funny images, greeting cards, or audio and video files. Computer viruses also spread through downloads on the Internet. They can be hidden in illicit software or other files or programs you might download.

To help avoid computer viruses, it's essential that you keep your computer current with the latest updates and antivirus tools, stay informed about recent threats, run your computer as a standard user (not as administrator), and that you follow a few basic rules when you surf the Internet, download files, and open attachments. Almost everyone who has had a computer in his or her home or work, has been a victim of some soft of virus or informatics worm.

Catch of the day!

RelevantKnowledge is a tracking cookie that may monitor your Internet habits and activities and display various surveys in popup windows. Your response to these popup surveys may be aggregated and may help determine what content you see when you are surfing the web. The RelevantKnowledge virus may be part of a real online market research community.

To completely purge RelevantKnowledge from your computer, you need to delete the files, folders, and Windows registry keys, and registry values associated with RelevantKnowledge. RelevantKnowledge can seriously slow down your computer. If your PC takes a lot longer than normal to restart or your Internet connection is extremely slow, your computer may well be infected with RelevantKnowledge. I found the RelevantKnowledge icon in the System Tray.

Different forms of electronic infection:

Viruses - A virus is a small piece of software that piggybacks on real programs. For example, a virus might attach itself to a program such as a spreadsheet program. Each time the spreadsheet program runs, the virus runs, too, and it has the chance to reproduce (by attaching to other programs) or wreak havoc.

E-mail viruses - An e-mail virus travels as an attachment to e-mail messages, and usually replicates itself by automatically mailing itself to dozens of people in the victim's e-mail address book. Some e-mail viruses don't even require a double-click -- they launch when you view the infected message in the preview pane of your e-mail software.

Trojan horses - A Trojan horse is simply a computer program. The program claims to do one thing (it may claim to be a game) but instead does damage when you run it (it may erase your hard disk). Trojan horses have no way to replicate automatically.

Worms - A worm is a small piece of software that uses computer networks and security holes to replicate itself. A copy of the worm scans the network for another machine that has a specific security hole. It copies itself to the new machine using the security hole, and then starts replicating from there, as well.

Malware is just another name for software that has an evil intent. Malware are programs designed to harm or compromise a computer are called malware (as in malicious software). Malware includes a wide array of nasty batches of code that can wreak havoc to your computer, your network and even the Internet itself. Some common forms of malware that might turn your computer into a zombie are Keloggers, Viruses, Rootkits, Backdoors, Spyware, Trojan Horses, and Worms.

Spyware collects personal information about you, like your passwords or other information you type into your computer. A keylogger is just what it sounds like. It is a program that logs every keystroke you make and then sends that information, including things like passwords, bank account numbers, and credit card numbers, to whomever is spying on you.

Phishing - While you may be taking steps to protect your computer from becoming infected by a virus, you may very well run into another, more insidious type of attack. Phishing and other social engineering attacks have been on the rise. Social engineering is a fancy term for someone trying to get you to give up your personal information -- online or in person -- so they can use it to steal from you. Anti-spam traps may catch e-mail messages coming from phishers, but the U.S. Computer Emergency Readiness Team says the best way for you to beat them at their own game is to be wary. And never give out your personal or financial information online.

Hijacker - A computer hacker who intends mischief or harm -- secretly infiltrates an unsuspecting victim's computer and uses it to conduct illegal activities. The user generally remains unaware that his computer has been taken over -- he can still use it, though it might slow. As his computer begins to either send out massive amounts of spam or attack Web pages, he becomes the focal point for any investigations involving his computer's suspicious activities.

Rootkits - a collection of programs that permits administrator-level control of a computer; not necessarily malware on its own, crackers use rootkits to control computers and evade detection Backdoors - methods of circumventing the normal operating-system procedures, allowing a cracker to access information on another computer.l