- a software program capable of reproducing itself and usually capable of causing great harm to files or other programs on the same computer. A computer virus is an executable program. Depend on the nature of a virus, it may cause damage of your hard disk contents, and/or interfere normal operation of your computer. By definition, a virus program is able to replicate itself. This means that the virus multiplies on a computer by making copies of itself. This replication is intentional; it is part of the virus program. In most cases, if a file that contains virus is executed or copied onto another computer, then that computer will also be "infected" by the same virus. A virus can be introduced to a computer system along with any software program. For Internet users, this threat can come from downloading files through FTP (file transfer protocol), or referencing email attachments. (Please refer to our web page on Handling Email's File Attachments for details.)
What can Viruses do?
■ Slow down email. Viruses that spread by email, such asSobig, can generate so much email traffic that servers slow down or crash. Even if this doesn't happen, companies may react to the risk by shutting down servers anyway. ■ Steal confidential data. The Bugbear-D worm records the user's keystrokes, including passwords, and gives the virus writer access to them. ■ Use your computer to attack websites.
MyDoom used infected computers to flood the SCO software company's website with data, making the site unusable (a denial of service attack). ■ Let other users hijack your computer. Some viruses place“backdoor Trojans” on the computer, allowing the virus writer to connect to your computer and use it for their own purposes. ■ Corrupt data. The Compatable virus makes changes to the data in Excel spreadsheets. ■ Delete data. The Sircam worm may attempt to delete or overwrite the hard disk on a certain day. ■ Disable hardware. CIH, also known as Chernobyl, attempts to overwrite the...
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