Viruses, worms, Trojan horses, botnets, malware and spyware are human-made software programs created specifically to wreak mischief on personal computers and networks. The chance of contracting one of these malicious programs over the Internet has increased dramatically. Unless you exercise great caution or routinely run anti-virus software, your computer will almost certainly become infected. Typically, you get a virus by opening infected e-mail attachments or downloading and installing infected software.The Good, the Bad and the Ugly
Some viruses are relatively harmless to individuals. They just attach themselves to outgoing messages and e-mail themselves to all the contacts listed in your address book. The sudden flood of e-mail overwhelms mail servers, causing the system to crash.
Other viruses are more destructive and may lie dormant until a certain date. Then they spring to life to do their dirty deeds. Sometimes a strange message appears on your screen, or data and programs may be modified. In the worst case, all the files on your hard drive may be wiped out. These pernicious programs start on one computer, then replicate quickly, infecting other computers around the world.
In 1988 a student at Cornell University sent out a virus out by accident, infecting more than 6,000 computers in minutes, nearly bringing the Internet to its knees. The "I Love You" virus caused over $1 billion USD in lost productivity as it crippled e-mail systems worldwide in 2000. And a worm called Conficker hobbled 15 million computers in 2008 and continues to do damage.Inoculate Your Computer
If you download and run software from the Internet or receive e-mail attachments, protect yourself by using anti-virus programs to scan attachments and downloaded programs to alert you of infection. The software also scans your hard drive periodically, searching for rogue viruses and deleting them.
For the latest information on specific computer viruses, visit the Symantec Threat Explorer.
Last update: Jan 12, 2010