Computer worm

[[File:Virus Blaster.jpg|thumb|right|325px|[[Hex dump]] of the [[Blaster (computer worm)|Blaster worm]], showing a message left for [[Microsoft]] [[CEO]] [[Bill Gates]] by the worm's creator]]

[[File:Virus Blaster.jpg|thumb|right|325px|[[Hex dump]] of the [[Blaster (computer worm)|Blaster worm]], showing a message left for [[Microsoft]] [[CEO]] [[Bill Gates]] by the worm's creator]]

[[File:Conficker.svg|thumb|Spread of [[Conficker worm]]]]

[[File:Conficker.svg|thumb|Spread of [[Conficker worm]]]]

A '''computer worm''' is a standalone [[malware]] [[computer program]] that replicates itself in order to spread to other computers.{{cite web|last=Barwise|first=Mike|title=What is an internet worm?|url=http://www.bbc.co.uk/webwise/guides/internet-worms|publisher=BBC|access-date=9 September 2010|archive-url=https://web.archive.org/web/20150324073759/http://www.bbc.co.uk/webwise/guides/internet-worms|archive-date=2015-03-24}} It often uses a [[computer network]] to spread itself, relying on security failures on the target computer to access it. It will use this machine asters as hosts, and this behavior will continue.{{Cite journal|last1=Zhang|first1=Changwang|last2=Zhou|first2=Shi|last3=Chain|first3=Benjamin M.|date=2015-05-15|title=Hybrid Epidemics—A Case Study on Computer Worm Conficker|journal=PLOS ONE|volume=10|issue=5|article-number=e0127478|doi=10.1371/journal.pone.0127478|pmid=25978309|pmc=4433115|arxiv=1406.6046|bibcode=2015PLoSO..1027478Z|issn=1932-6203|doi-access=free}} Computer worms use [[recursion (computer science)|recursive methods]] to copy themselves without host programs and distribute themselves based on exploiting the advantages of [[exponential growth]], thus controlling and infecting more and more computers in a short time.{{Cite journal|last=Marion|first=Jean-Yves|date=2012-07-28|title=From Turing machines to computer viruses|journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences|volume=370|issue=1971|pages=3319–3339|doi=10.1098/rsta.2011.0332|pmid=22711861|bibcode=2012RSPTA.370.3319M|issn=1364-503X|doi-access=free}} Worms almost always cause at least some harm to the network, even if only by consuming [[bandwidth (computing)|bandwidth]], whereas [[computer virus|viruses]] almost always corrupt or modify files on a targeted computer.

A '''computer worm''' is a standalone [[malware]] [[computer program]] that replicates itself in order to spread to other computers.{{cite web|last=Barwise|first=Mike|title=What is an internet worm?|url=http://www.bbc.co.uk/webwise/guides/internet-worms|publisher=BBC|access-date=9 September 2010|archive-url=https://web.archive.org/web/20150324073759/http://www.bbc.co.uk/webwise/guides/internet-worms|archive-date=2015-03-24}} It often uses a [[computer network]] to spread itself, relying on security failures on the target computer to access it. It will use this machine as a host to scan and infect other computers. When these new worm-invaded computers are controlled, the worm will continue to scan and infect other computers using these computers as hosts, and this behavior will continue.{{Cite journal|last1=Zhang|first1=Changwang|last2=Zhou|first2=Shi|last3=Chain|first3=Benjamin M.|date=2015-05-15|title=Hybrid Epidemics—A Case Study on Computer Worm Conficker|journal=PLOS ONE|volume=10|issue=5|article-number=e0127478|doi=10.1371/journal.pone.0127478|pmid=25978309|pmc=4433115|arxiv=1406.6046|bibcode=2015PLoSO..1027478Z|issn=1932-6203|doi-access=free}} Computer worms use [[recursion (computer science)|recursive methods]] to copy themselves without host programs and distribute themselves based on exploiting the advantages of [[exponential growth]], thus controlling and infecting more and more computers in a short time.{{Cite journal|last=Marion|first=Jean-Yves|date=2012-07-28|title=From Turing machines to computer viruses|journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences|volume=370|issue=1971|pages=3319–3339|doi=10.1098/rsta.2011.0332|pmid=22711861|bibcode=2012RSPTA.370.3319M|issn=1364-503X|doi-access=free}} Worms almost always cause at least some harm to the network, even if only by consuming [[bandwidth (computing)|bandwidth]], whereas [[computer virus|viruses]] almost always corrupt or modify files on a targeted computer.

Many worms are designed only to spread, and do not attempt to change the systems they pass through. However, as the [[Morris worm]] and [[Mydoom]] showed, even these "payload-free" worms can cause major disruption by increasing network traffic and other unintended effects.

Many worms are designed only to spread, and do not attempt to change the systems they pass through. However, as the [[Morris worm]] and [[Mydoom]] showed, even these "payload-free" worms can cause major disruption by increasing network traffic and other unintended effects.