Different types of computer Viruses- A broad outline
As with human viruses, computer viruses also have specialism depending on the infectedarea, and amount of damage. There are many types of virus. The basic category of theviruses is:
Boot viruses: The viruses, which infect, boot records on hard disks or other booting
devices are called boot viruses. These viruses replace the boot record program and copy it
elsewhere.
Example: Disk Killer, Stone Virus
Program viruses: These viruses infect the executable program files, for example, those
with extensions like .EXE, .COM, .SYS etc. Virus is loaded in the memory with the programs
on execution and thus it makes copies of itself and infects the file.
Example: Sunday
Multipartite viruses: This virus is a fusion of Boot and Program viruses. They infect
program files as the first step. On execution of these infected files, these viruses infect the
boot record.
Example: Invader, Tequila
Stealth viruses: These viruses are hard to detect. They use different techniques to avoid
detection.
Example: Whale, Joshi
Macro Viruses: It is a new kind of virus infecting the macros within a document.
Example: Nuclear, DMV
The above mentioned types of virus are but a broad category of the viruses. They are many
specialized versions available.