Virus vs. worm
Gene Spafford
> This is probably a simple question, but I haven't heard it asked (or
>answered). What is the difference between a virus and a worm?
Well, there are many differing definitions, with one extreme being
that all worms are viruses.
The definitions I think most people use are:
A virus is code that cannot run on its own. It is inserted into
another ("host") program, and cause that program to run the virus
code when the host is run. The virus code, when run, will insert a
copy of itself in another "host," then possibly do some other task
(often known as the "manipulation" task), then possibly execute the
original host code. Viruses are not self-contained programs.
A worm is a program that can run by itself. It is self-contained in
that it can run as an independent program. It may use system programs
to propagate itself. Worms travel (and possibly multiply) over
communications links. They do not necessarily do anything other than
travel from machine to machine (or propagate around a network), but
they may also perform manipulation tasks, carry viruses, etc.
Gene Spafford
NSF/Purdue/U of Florida Software Engineering Research Center,
Dept. of Computer Sciences, Purdue University, W. Lafayette IN 47907-2004
Internet: sp...@cs.purdue.edu uucp: ...!{decwrl,gatech,ucbvax}!purdue!spaf