Editing Computer worm (section)

==Features==
'''Independence'''

Computer viruses generally require a host program.<ref>{{Cite web|title=Worm vs. Virus: What's the Difference and Does It Matter?|url=https://www.avast.com/c-worm-vs-virus|access-date=2021-10-08|website=Worm vs. Virus: What's the Difference and Does It Matter?|language=en}}</ref> The virus writes its own code into the host program. When the program runs, the written virus program is executed first, causing infection and damage. A worm does not need a host program, as it is an independent program or code chunk. Therefore, it is not restricted by the [[Computer program|host program]], but can run independently and actively carry out attacks.<ref>{{Cite book|last=Yeo, Sang-Soo.|title=Computer science and its applications : CSA 2012, Jeju, Korea, 22-25.11.2012|date=2012|publisher=Springer|isbn=978-94-007-5699-1|pages=515|oclc=897634290}}</ref><ref>{{Cite journal|last1=Yu|first1=Wei|last2=Zhang|first2=Nan|last3=Fu|first3=Xinwen|last4=Zhao|first4=Wei|date=October 2010|title=Self-Disciplinary Worms and Countermeasures: Modeling and Analysis|journal=IEEE Transactions on Parallel and Distributed Systems|volume=21|issue=10|pages=1501–1514|doi=10.1109/tpds.2009.161|s2cid=2242419|issn=1045-9219}}</ref>

'''Exploit attacks'''

Because a worm is not limited by the host program, worms can take advantage of various operating system vulnerabilities to carry out active attacks. For example, the "[[Nimda]]" virus [[Exploit (computer security)|exploits]] [[Vulnerability (computing)|vulnerabilities]] to attack.

'''Complexity'''

Some worms are combined with web page scripts, and are hidden in [[HTML]] pages using [[VBScript]], [[ActiveX]] and other technologies. When a user accesses a webpage containing a virus, the virus automatically resides in memory and waits to be triggered. There are also some worms that are combined with [[Backdoor (computing)|backdoor]] programs or [[Trojan horse (computing)|Trojan horses]], such as "[[Code Red (computer worm)|Code Red]]".<ref>{{Citation|last=Brooks|first=David R.|title=Programming in HTML and PHP|chapter=Introducing HTML|date=2017|pages=1–10|publisher=Springer International Publishing|isbn=978-3-319-56972-7|doi=10.1007/978-3-319-56973-4_1|series=Undergraduate Topics in Computer Science}}</ref>

'''Contagiousness'''

Worms are more infectious than traditional viruses. They not only infect local computers, but also all servers and clients on the network based on the local computer. Worms can easily spread through [[shared folder]]s, [[Email|e-mails]],<ref>{{Cite journal |last1=Deng |first1=Yue |last2=Pei |first2=Yongzhen |last3=Li |first3=Changguo |date=2021-11-09 |title=Parameter estimation of a susceptible–infected–recovered–dead computer worm model |url=http://journals.sagepub.com/doi/10.1177/00375497211009576 |journal=Simulation |language=en |volume=98 |issue=3 |pages=209–220 |doi=10.1177/00375497211009576 |s2cid=243976629 |issn=0037-5497|url-access=subscription }}</ref> malicious web pages, and servers with a large number of vulnerabilities in the network.<ref>{{Cite journal|last=Lawton|first=George|date=June 2009|title=On the Trail of the Conficker Worm|journal=Computer|volume=42|issue=6|pages=19–22|doi=10.1109/mc.2009.198|s2cid=15572850|issn=0018-9162}}</ref>