Computer Threat- Viruses

Computer viruses are generally called “viruses” as they share some traits of biological viruses. A computer virus passes from computer to computer like a biological virus passes from person to person.

A computer virus must piggyback on top of some other program or document in order to get executed. Once it is running, it is able to
infect other programs or documents.

 

E-Mail Viruses

 The latest thing in the world of viruses is email viruses, and the
Melissa virus in march 1999 was spectacular. Melissa spread in
Microsoft word documents sent via emails and it worked like this:
someone created the virus as word document uploaded to an Internet
newsgroup. Anyone who downloaded the document and opened it would
trigger the virus. The virus would then send the document in e-mail
message to the first 50 people in the person’s address book. The
e-mail message contained a friendly note that included the person’s
name, so recipient would open the document thinking it was harmless.
The virus would then create 50 new messages from the recipients
machine. As a result, the Melissa virus was the fastest spreading
virus ever seen. This virus forced many number of large companies to
shut down their e-mail systems.
The “I Love You” virus which appeared on 4th may 2000 ,was even
simpler. It contained a piece of code as an attachment, people who
double clicked  on attachment allowed the code to executed. The code sent copies of itself to everyone in the victim’s machine. This is as simple as a virus can get. It was more like a Trojan Horse distributed by e-mails than it is a virus.