An example of such is the Jerusalem Virus Polymorphic viruses Viruses that can change each time they spread from one computer to another. These types of viruses are harder to detect. An example of such is the Scream Virus. Armoured viruses Viruses that are specifically written to make it difficult for an antivirus researcher to find out how they work and what they do. An example of such is Stealth Boot Virus Computer viruses can be a serious threat to an organization since they usually result in loss of productivity.
Viruses can quickly spread to a large number of computer systems or networks.
Access to personal computers is usually not restricted. This means that anyone could introduce a virus, intentionally or otherwise, to the environment. Viruses can mutate as they propagate through an environment. These types of viruses are very hard to detect and usually more harmful. Although techniques for detecting and removing known viruses have been developed and are relatively cheap to acquire, the problem will not disappear since not everyone protects and monitors their system or takes the steps necessary to prevent infection.