Other types of viruses are worm, logic bomb, and stealth program. File infectors spread these viruses from program to program. Ironically enough, a vaccine can detect these viruses and is sometimes capable of removing them. Hackers are also a common nuisance to those who try to cease computer crime. A hacker usually breaks into computer systems for the fun of it.
Money is one of the four motivations for computer crime.
Ideology, compromise, and egotism are the other three. The oppurtunity to commit a computer crime requires knowledge and access. Obviously, not everyone has the knowledge to break in to a system and cover up the evidence. For those who are capable of covering up the evidence, they do not get caught, or if they do, it is not a serious punishment because of lack of sufficent evidence. A good thing is that the government has established that computer crime is a problem and they have taken steps.