Computer Viruses

Welcome to Computer Viruses
Strange as it may sound, the computer virus is something of an Information Age marvel. On one hand, viruses show us how vulnerable we are - a properly engineered virus can have a devastating effect, disrupting productivity and doing billions of dollars in damages. On the other hand, they show us how sophisticated and interconnected human beings have become.

For example, experts estimate that the Mydoom worm infected approximately a quarter-million computers in a single day in January 2004. Back in March 1999, the Melissa virus was so powerful that it forced Microsoft and a number of other very large companies to completely turn off their e-mail systems until the virus could be contained. The ILOVEYOU virus in 2000 had a similarly devastating effect. In January 2007, a worm called Storm appeared - by October, experts believed up to 50 million computers were infected. That's pretty impressive when you consider that many viruses are incredibly simple.

  The most common forms of electronic infection are:  
 * 1) Viruses <span style="font-size:12.0pt; font-family:"Tahoma","sans-serif";mso-fareast-font-family:"Times New Roman"; mso-fareast-language:EN-IE">: 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.
 * 2) <span style="font-size:12.0pt;font-family:"Tahoma","sans-serif"; mso-fareast-font-family:"Times New Roman";mso-fareast-language:EN-IE; mso-bidi-font-weight:bold">E-mail viruses <span style="font-size:12.0pt; font-family:"Tahoma","sans-serif";mso-fareast-font-family:"Times New Roman"; mso-fareast-language:EN-IE">: 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
 * 3) <span style="font-size:12.0pt;font-family:"Tahoma","sans-serif"; mso-fareast-font-family:"Times New Roman";mso-fareast-language:EN-IE; mso-bidi-font-weight:bold">Trojan horses <span style="font-size:12.0pt; font-family:"Tahoma","sans-serif";mso-fareast-font-family:"Times New Roman"; mso-fareast-language:EN-IE">: A <span style="font-size:12.0pt;font-family:"Tahoma","sans-serif";mso-fareast-font-family: "Times New Roman";color:blue;mso-fareast-language:EN-IE">Trojan horse<span style="font-size:12.0pt;font-family:"Tahoma","sans-serif";mso-fareast-font-family: "Times New Roman";mso-fareast-language:EN-IE"> 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.
 * 4) <span style="font-size:12.0pt;font-family:"Tahoma","sans-serif"; mso-fareast-font-family:"Times New Roman";mso-fareast-language:EN-IE; mso-bidi-font-weight:bold">Virus.jpg <span style="font-size:12.0pt; font-family:"Tahoma","sans-serif";mso-fareast-font-family:"Times New Roman"; mso-fareast-language:EN-IE">: 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.

<p class="MsoNormal" style="margin-bottom:0cm;margin-bottom:.0001pt;line-height: normal"><span style="font-size:12.0pt;font-family:"Tahoma","sans-serif"; mso-fareast-font-family:"Times New Roman";mso-fareast-language:EN-IE">Description :

<p style="margin:0cm;margin-bottom:.0001pt"><span style="font-family:"Tahoma","sans-serif"">A computer virus is a <span style="font-family:"Tahoma","sans-serif";color:windowtext;text-decoration:none; text-underline:none">computer program<span style="font-family:"Tahoma","sans-serif""> that can replicate itself and spread from one computer to another. The term "virus" is also commonly, but erroneously, used to refer to other types of <span style="font-family:"Tahoma","sans-serif";color:windowtext;text-decoration:none; text-underline:none">malware<span style="font-family:"Tahoma","sans-serif"">, including but not limited to <span style="font-family: "Tahoma","sans-serif";color:windowtext;text-decoration:none;text-underline: none">adware<span style="font-family:"Tahoma","sans-serif""> and <span style="font-family:"Tahoma","sans-serif";color:windowtext;text-decoration:none; text-underline:none">spyware<span style="font-family:"Tahoma","sans-serif""> programs that do not have a reproductive ability.

<p style="margin:0cm;margin-bottom:.0001pt"><span style="font-family:"Tahoma","sans-serif";color:windowtext;text-decoration:none; text-underline:none">Malware<span style="font-family:"Tahoma","sans-serif""> includes computer viruses, <span style="font-family:"Tahoma","sans-serif";color:windowtext;text-decoration:none; text-underline:none">computer worms<span style="font-family:"Tahoma","sans-serif"">, <span style="font-family:"Tahoma","sans-serif"; color:windowtext;text-decoration:none;text-underline:none">ransomware<span style="font-family:"Tahoma","sans-serif"">, <span style="font-family:"Tahoma","sans-serif"; color:windowtext;text-decoration:none;text-underline:none">trojan horses<span style="font-family:"Tahoma","sans-serif"">, <span style="font-family:"Tahoma","sans-serif";color:windowtext;text-decoration:none; text-underline:none">keyloggers<span style="font-family:"Tahoma","sans-serif"">, most <span style="font-family:"Tahoma","sans-serif";color:windowtext;text-decoration:none; text-underline:none">rootkits<span style="font-family:"Tahoma","sans-serif"">, <span style="font-family:"Tahoma","sans-serif";color:windowtext;text-decoration:none; text-underline:none">spyware<span style="font-family:"Tahoma","sans-serif"">, dishonest adware, malicious <span style="font-family:"Tahoma","sans-serif"; color:windowtext;text-decoration:none;text-underline:none">BHOs<span style="font-family:"Tahoma","sans-serif""> and other malicious software. The majority of active malware threats are usually trojans or worms rather than viruses. Malware such as trojan horses and worms is sometimes confused with viruses, which are technically different: a worm can exploit security <span style="font-family:"Tahoma","sans-serif"; color:windowtext;text-decoration:none;text-underline:none">vulnerabilities<span style="font-family:"Tahoma","sans-serif""> to spread itself automatically to other computers through networks, while a trojan horse is a program that appears harmless but hides malicious functions. Worms and trojan horses, like viruses, may harm a computer system's data or performance. Some viruses and other malware have symptoms noticeable to the computer user, but many are surreptitious or simply do nothing to call attention to themselves. Some viruses do nothing beyond reproducing themselves.