Computer Viruses

A computer virus is a computer program that interferes with a computer's hardware or operating system. Although the name might imply, viruses are not naturally occuring. They are written by individuals with malicious intent or the challenge of testing system security. Viruses are often difficult to detect, self-replicating, and can damage data, hardware, or gain access to private information. Once a virus is active, it may replicate by writing itself to floppy disks, to the hard drive, into legitimate computer programs, or across computer networks. Other variations include:

Trojan Horse
A Trojan horse appears to be something interesting and harmless, such as a game, but when it runs it may have harmful effects.


Logic Bomb
A logic bomb delivers its payload when it is triggered by a specific condition, such as when a particular date or time is reached or when a combination of letters is typed.


Worm
A worm only makes copies of itself, but it can take up computer memory slowing the computer's processes, or clogging a network with high traffic.

With the proliferation of e-mail and connected PCs, e-mail worms have become very common. Some worms read an infected computer's address books and send e-mails containing the virus to others. Since the e-mail appears to be coming from someone known, a recipient is more likely to open and/or execute the attached virus.


Spoofing
Another complication with e-mail worms is the concept of spoofing. Spoofing manipulates e-mail messages to make it appear to be coming from someone else. This makes it very difficult to track down who is actually infected, and can also be embarrassing to the "spoofed" sender.

Virus infections can occur by running programs or attachments from untrusted sources. To avoid becoming infected, never run a program or attachment from someone you don't know. However, e-mail viruses are generally received from people you do know, so if a message seems suspicious and has an attachment, contact the sender prior to opening.


Anti-virus
The best way to prevent infection is to protect yourself with up-to-date antivirus software. Both McAfee and Norton have automatic subscription services to keep virus profiles current.


Operating System Patches
Microsoft Windows is the most popular operating system, and as functionality is improved, some individuals are attemping to exploite weaknesses in its security. Once these problems are identified, free patches and updates are generally made available. Be sure to check that your operating system is current. Microsoft Windows can be checked at: http://windowsupdate.microsoft.com