Viruses replicate on the resources of the local machine.
Unlike worms, viruses do not use network services to propagate or penetrate other computers. A copy of a virus will reach remote computers only if the infected object is, for some reason unrelated to the virus function, activated on another computer. For example:
- when infecting accessible disks, a virus penetrates a file located on a network resource
- a virus copies itself to a removable storage device or infects a file on a removable device
- a user sends an email with an infected attachment.