A virus may try to avoid detection by disguising itself as a legitimate program. Viruses are often rewritten and adjusted so that they will not be detected.
Viruses are the number-one method of computer vandalism.
The first computer viruses were designed by programmers who wanted to show off their programming skills and to demonstrate how easily computer security systems could be infiltrated. There are over 5000 known viruses, and new virus strains continue to show up regularly. The rate of virus infection is also increasing. In the United States, creating or distributing a virus is classified as a computer crime, and is a federal offense. The Electronic Privacy Act of 1986 is the most noteworthy legislation against the fraudulent use of computers.