Antivirus software#Identification methods
{{Short description|Computer software to defend against malicious computer viruses}}
{{Redirect|Antivirus|the medication|Antiviral drug}}
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File:ClamTk 5.27.png, an open-source antivirus based on the ClamAV antivirus engine, was originally developed by Tomasz Kojm in 2001.]]
Antivirus software (abbreviated to AV software), also known as anti-malware, is a computer program used to prevent, detect, and remove malware.
Antivirus software was originally developed to detect and remove computer viruses, hence the name. However, with the proliferation of other malware, antivirus software started to protect against other computer threats. Some products also include protection from malicious URLs, spam, and phishing.{{cite web|title=What is antivirus software?|url=http://www.microsoft.com/security/resources/antivirus-whatis.aspx|url-status=live|archive-url=https://web.archive.org/web/20110411203211/http://www.microsoft.com/security/resources/antivirus-whatis.aspx|archive-date=April 11, 2011|publisher=Microsoft}}
History
{{further|History of computer viruses}}
{{See also|Timeline of computer viruses and worms}}
= 1971–1980 period (pre-antivirus days) =
The first known computer virus appeared in 1971 and was dubbed the "Creeper virus".{{cite web|url=http://vx.netlux.org/lib/atc01.html|title=The Evolution of Viruses and Worms|author=Thomas Chen, Jean-Marc Robert|date=2004|access-date=February 16, 2009|url-status=dead|archive-url=https://web.archive.org/web/20090517083356/http://vx.netlux.org/lib/atc01.html|archive-date=May 17, 2009}} This computer virus infected Digital Equipment Corporation's (DEC) PDP-10 mainframe computers running the TENEX operating system.[https://www.theguardian.com/technology/2009/oct/23/internet-history From the first email to the first YouTube video: a definitive internet history] {{webarchive|url=https://web.archive.org/web/20161231172753/https://www.theguardian.com/technology/2009/oct/23/internet-history |date=December 31, 2016}}. Tom Meltzer and Sarah Phillips. The Guardian. October 23, 2009IEEE Annals of the History of Computing, Volumes 27–28. IEEE Computer Society, 2005. [https://books.google.com/books?id=xv9UAAAAMAAJ&q=Creeper+%22computer+worm%22 74] {{webarchive|url=https://web.archive.org/web/20160513081502/https://books.google.com/books?id=xv9UAAAAMAAJ&q=Creeper+%22computer+worm%22&dq=Creeper+%22computer+worm%22&hl=en&ei=pRzNTeaOBdGbtwe81ZyNDg&sa=X&oi=book_result&ct=result&resnum=3&ved=0CEUQ6AEwAg |date=May 13, 2016}}: "[...]from one machine to another led to experimentation with the Creeper program, which became the world's first computer worm: a computation that used the network to recreate itself on another node, and spread from node to node."
The Creeper virus was eventually deleted by a program created by Ray Tomlinson and known as "The Reaper".{{cite web|url=http://corewar.co.uk/creeper.htm|title=Core War: Creeper & Reaper|first=John|last=Metcalf|date=2014|access-date=May 1, 2014|url-status=live|archive-url=https://web.archive.org/web/20140502001343/http://corewar.co.uk/creeper.htm|archive-date=May 2, 2014}} Some people consider "The Reaper" the first antivirus software ever written – it may be the case, but it is important to note that the Reaper was actually a virus itself specifically designed to remove the Creeper virus.{{cite web|url=http://virus.wikidot.com/creeper|title=Creeper – The Virus Encyclopedia|url-status=live|archive-url=https://web.archive.org/web/20150920104511/http://virus.wikidot.com/creeper|archive-date=September 20, 2015}}
The Creeper virus was followed by several other viruses. The first known that appeared "in the wild" was "Elk Cloner", in 1981, which infected Apple II computers.{{cite web|url=http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci989616,00.html|title=Elk Cloner|access-date=December 10, 2010|url-status=live|archive-url=https://web.archive.org/web/20110107111044/http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci989616,00.html|archive-date=January 7, 2011}}{{cite web|url=http://science.discovery.com/top-ten/2009/computer-viruses/computer-viruses-10.html|title=Top 10 Computer Viruses: No. 10 – Elk Cloner|work=The Science Channel |access-date=December 10, 2010|url-status=live|archive-url=https://web.archive.org/web/20110207034138/http://science.discovery.com/top-ten/2009/computer-viruses/computer-viruses-10.html|archive-date=February 7, 2011}}{{cite web|url=http://www.infoniac.com/hi-tech/list-of-computer-viruses-developed-in-1980s.html|title=List of Computer Viruses Developed in 1980s|access-date=December 10, 2010|url-status=live|archive-url=https://web.archive.org/web/20110724010543/http://www.infoniac.com/hi-tech/list-of-computer-viruses-developed-in-1980s.html|archive-date=July 24, 2011}}
In 1983, the term "computer virus" was coined by Fred Cohen in one of the first ever published academic papers on computer viruses.[http://www.eecs.umich.edu/%7Eaprakash/eecs588/handouts/cohen-viruses.html Fred Cohen: "Computer Viruses – Theory and Experiments" (1983)] {{webarchive|url=https://web.archive.org/web/20110608214157/http://www.eecs.umich.edu/%7Eaprakash/eecs588/handouts/cohen-viruses.html |date=June 8, 2011}}. Eecs.umich.edu (November 3, 1983). Retrieved on 2017-01-03. Cohen used the term "computer virus" to describe programs that: "affect other computer programs by modifying them in such a way as to include a (possibly evolved) copy of itself."{{cite journal|title=Invited Paper: On the Implications of Computer Viruses and Methods of Defense|journal=Computers & Security|first=Fred|last=Cohen|date=April 1, 1988|volume=7|issue=2|pages=167–184 |doi=10.1016/0167-4048(88)90334-3}} (note that a more recent definition of computer virus has been given by the Hungarian security researcher Péter Szőr: "a code that recursively replicates a possibly evolved copy of itself").{{sfn|Szor|2005|p={{page needed|date=August 2020}}}}{{cite web |url=https://www.virusbtn.com/virusbulletin/archive/2013/12/vb201312-obituary-Peter-Szor |title=Virus Bulletin :: In memoriam: Péter Ször 1970–2013 |url-status=live |archive-url= https://web.archive.org/web/20140826120240/https://www.virusbtn.com/virusbulletin/archive/2013/12/vb201312-obituary-Peter-Szor |archive-date=August 26, 2014}}
The first IBM PC compatible "in the wild" computer virus, and one of the first real widespread infections, was "Brain" in 1986. From then, the number of viruses has grown exponentially.{{cite journal |url=http://csrc.nist.gov/publications/nistir/threats/subsubsection3_3_1_1.html |date=October 1992 |title=History of Viruses |doi=10.6028/NIST.IR.4939 |url-status=live |archive-url= https://web.archive.org/web/20110423085041/http://csrc.nist.gov/publications/nistir/threats/subsubsection3_3_1_1.html |archive-date=April 23, 2011|last1=Bassham |first1=Lawrence |last2=Polk |first2=W.|journal=Nistir 4939 |doi-access=free }}{{cite web |last=Leyden |first=John |url=https://www.theregister.co.uk/2006/01/19/pc_virus_at_20/ |title=PC virus celebrates 20th birthday |date=January 19, 2006 |work=The Register |access-date=March 21, 2011 |url-status=live |archive-url= https://web.archive.org/web/20100906023749/http://www.theregister.co.uk/2006/01/19/pc_virus_at_20/ |archive-date=September 6, 2010}} Most of the computer viruses written in the early and mid-1980s were limited to self-reproduction and had no specific damage routine built into the code. That changed when more and more programmers became acquainted with computer virus programming and created viruses that manipulated or even destroyed data on infected computers.{{Cite web|title=The History of Computer Viruses|date=November 10, 2017|url=https://www.bbvaopenmind.com/en/technology/digital-world/the-history-of-computer-viruses/}}
Before internet connectivity was widespread, computer viruses were typically spread by infected floppy disks. Antivirus software came into use, but was updated relatively infrequently. During this time, virus checkers essentially had to check executable files and the boot sectors of floppy disks and hard disks. However, as internet usage became common, viruses began to spread online.{{cite web|url = http://www.pandasecurity.com/homeusers/media/press-releases/viewnews?noticia=4974&entorno=&ver=&pagina=&producto=|title = (II) Evolution of computer viruses|access-date = June 20, 2009|last = Panda Security|date=April 2004|archive-url = https://web.archive.org/web/20090802042225/http://www.pandasecurity.com/homeusers/media/press-releases/viewnews?noticia=4974&entorno=&ver=&pagina=&producto= |archive-date = August 2, 2009}}
= 1980–1990 period (early days) =
There are competing claims for the innovator of the first antivirus product. Possibly, the first publicly documented removal of an "in the wild" computer virus (the "Vienna virus") was performed by Bernd Fix in 1987.[https://web.archive.org/web/20090713091733/http://www.viruslist.com/en/viruses/encyclopedia?chapter=153311150 Kaspersky Lab Virus list]. viruslist.com{{cite web | url = http://www.research.ibm.com/antivirus/timeline.htm | publisher = IBM | title = Virus timeline | first = Joe | last = Wells | date = August 30, 1996 | access-date = June 6, 2008| archive-url= https://web.archive.org/web/20080604011721/http://www.research.ibm.com/antivirus/timeline.htm| archive-date= June 4, 2008 | url-status= live}}
In 1987, Andreas Lüning and Kai Figge, who founded G Data Software in 1985, released their first antivirus product for the Atari ST platform.{{cite web|url = https://www.gdatasoftware.com/about-g-data/company-profile|title = G Data presents first Antivirus solution in 1987|access-date = December 13, 2017|last = G Data Software AG|year = 2017|url-status = live|archive-url = https://web.archive.org/web/20170315111115/https://www.gdatasoftware.com/about-g-data/company-profile|archive-date = March 15, 2017|df = mdy-all}} In 1987, the Ultimate Virus Killer (UVK) was also released.{{cite web|url = http://st-news.com/uvk-book/|title = The ultimate Virus Killer Book and Software|access-date = July 6, 2016|last = Karsmakers|first = Richard|date = January 2010|url-status = live|archive-url = https://web.archive.org/web/20160729032353/http://st-news.com/uvk-book/|archive-date = July 29, 2016|df = mdy-all}} This was the de facto industry standard virus killer for the Atari ST and Atari Falcon, the last version of which (version 9.0) was released in April 2004.{{Citation needed|date=July 2016}} In 1987, in the United States, John McAfee founded the McAfee company and, at the end of that year, he released the first version of VirusScan.{{cite book| last = Cavendish| first = Marshall| title = Inventors and Inventions, Volume 4| url = https://books.google.com/books?id=YcPvV893aXgC| year = 2007| publisher = Paul Bernabeo| isbn = 978-0761477679| page = 1033}} Also in 1987 (in Czechoslovakia), Peter Paško, Rudolf Hrubý, and Miroslav Trnka created the first version of NOD antivirus.{{cite web
|url = https://www.eset.com/int/about/
|title = About ESET Company
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|archive-url = https://web.archive.org/web/20161028220311/https://www.eset.com/int/about/
|archive-date = October 28, 2016
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|url = http://www.vsquare.co.th/index.php?option=com_djcatalog2&view=item&id=7:eset-nod32-antivirus&cid=1:soft-ware&Itemid=159
|title = ESET NOD32 Antivirus
|publisher = Vision Square
|date = February 16, 2016
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|archive-url = https://web.archive.org/web/20160224031719/http://www.vsquare.co.th/index.php?option=com_djcatalog2&view=item&id=7:eset-nod32-antivirus&cid=1:soft-ware&Itemid=159
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In 1987, Fred Cohen wrote that there is no algorithm that can perfectly detect all possible computer viruses.Cohen, Fred, [https://web.archive.org/web/20110604155118/http://www.research.ibm.com/antivirus/SciPapers/VB2000DC.htm An Undetectable Computer Virus (Archived)], 1987, IBM
Finally, at the end of 1987, the first two heuristic antivirus utilities were released: Flushot Plus by Ross Greenberg{{cite web |author=Yevics, Patricia A. |url=https://www.americanbar.org/newsletter/publications/gp_solo_magazine_home/gp_solo_magazine_index/tsp97flushot.html |title=Flu Shot for Computer Viruses |publisher=americanbar.org |url-status=live |archive-url= https://web.archive.org/web/20140826115405/https://www.americanbar.org/newsletter/publications/gp_solo_magazine_home/gp_solo_magazine_index/tsp97flushot.html |archive-date=August 26, 2014}}{{cite web |url=https://strom.wordpress.com/2010/04/01/ross-greenberg/ |title=How friends help friends on the Internet: The Ross Greenberg Story |first=David |last=Strom |publisher=wordpress.com |date=April 1, 2010 |archive-url= https://web.archive.org/web/20140826115800/https://strom.wordpress.com/2010/04/01/ross-greenberg/ |archive-date=August 26, 2014 |url-status=live}}{{cite web |title=Anti-virus is 30 years old |url=http://www.spgedwards.com/2012/04/anti-virus-is-30-years-old.html |publisher=spgedwards.com |date=April 2012 |archive-url= https://web.archive.org/web/20150427213954/http://www.spgedwards.com/2012/04/anti-virus-is-30-years-old.html |archive-date=April 27, 2015 |url-status=live}} and Anti4us by Erwin Lanting.{{cite web |url=http://www.techlineinfo.com/a-brief-history-of-antivirus-software/ |title=A Brief History of Antivirus Software |publisher=techlineinfo.com |url-status=live |archive-url= https://web.archive.org/web/20140826120523/http://www.techlineinfo.com/a-brief-history-of-antivirus-software/ |archive-date=August 26, 2014}} In his O'Reilly book, Malicious Mobile Code: Virus Protection for Windows, Roger Grimes described Flushot Plus as "the first holistic program to fight malicious mobile code (MMC)."{{cite book
|last = Grimes
|first = Roger A.
|title = Malicious Mobile Code: Virus Protection for Windows
|publisher = O'Reilly Media, Inc.
|date = June 1, 2001
|pages = 522
|url = https://books.google.com/books?id=GKDtVYJ0wesC&q=%22Ross+Greenberg%22+flushot&pg=PA43
|isbn = 9781565926820
|url-status = live
|archive-url = https://web.archive.org/web/20170321110232/https://books.google.com/books?id=GKDtVYJ0wesC
|archive-date = March 21, 2017
|df = mdy-all
}}
However, the kind of heuristic used by early AV engines was totally different from those used today. The first product with a heuristic engine resembling modern ones was F-PROT in 1991.{{cite web |url=http://www.frisk.is/fyrirtaeki.html |title=Friðrik Skúlason ehf. |language=is |url-status=dead |archive-url= https://web.archive.org/web/20060617090822/http://www.frisk.is/fyrirtaeki.html |archive-date=June 17, 2006}} Early heuristic engines were based on dividing the binary into different sections: data section, code section (in a legitimate binary, it usually starts always from the same location). Indeed, the initial viruses re-organized the layout of the sections, or overrode the initial portion of a section in order to jump to the very end of the file where malicious code was located—only going back to resume execution of the original code. This was a very specific pattern, not used at the time by any legitimate software, which represented an elegant heuristic to catch suspicious code. Other kinds of more advanced heuristics were later added, such as suspicious section names, incorrect header size, regular expressions, and partial pattern in-memory matching.
In 1988, the growth of antivirus companies continued. In Germany, Tjark Auerbach founded Avira (H+BEDV at the time) and released the first version of AntiVir (named "Luke Filewalker" at the time). In Bulgaria, Vesselin Bontchev released his first freeware antivirus program (he later joined FRISK Software). Also Frans Veldman released the first version of ThunderByte Antivirus, also known as TBAV (he sold his company to Norman Safeground in 1998). In Czechoslovakia, Pavel Baudiš and Eduard Kučera founded Avast Software (at the time ALWIL Software) and released their first version of avast! antivirus. In June 1988, in South Korea, Ahn Cheol-Soo released its first antivirus software, called V1 (he founded AhnLab later in 1995). Finally, in autumn 1988, in the United Kingdom, Alan Solomon founded S&S International and created his Dr. Solomon's Anti-Virus Toolkit (although he launched it commercially only in 1991 – in 1998 Solomon's company was acquired by McAfee, then known as Network Associates Inc.).
Also in 1988, a mailing list named VIRUS-L{{cite web |url=http://securitydigest.org/virus/mirror/www.phreak.org-virus_l/ |title=The 'Security Digest' Archives (TM) : www.phreak.org-virus_l |url-status=live |archive-url= https://web.archive.org/web/20100105064155/http://securitydigest.org/virus/mirror/www.phreak.org-virus_l/ |archive-date=January 5, 2010}} was started on the BITNET/EARN network where new viruses and the possibilities of detecting and eliminating viruses were discussed. Some members of this mailing list were: Alan Solomon, Eugene Kaspersky (Kaspersky Lab), Friðrik Skúlason (FRISK Software), John McAfee (McAfee), Luis Corrons (Panda Security), Mikko Hyppönen (F-Secure), Péter Szőr, Tjark Auerbach (Avira) and Vesselin Bontchev (FRISK Software).
In 1989, in Iceland, Friðrik Skúlason created the first version of F-PROT Anti-Virus (he founded FRISK Software only in 1993). Meanwhile, in the United States, Symantec (founded by Gary Hendrix in 1982) launched its first Symantec antivirus for Macintosh (SAM).{{cite web |url=http://www.pcm.com/n/Symantec-Softwares/manufacturers-14|title=Symantec Softwares and Internet Security at PCM|url-status=live|archive-url=https://web.archive.org/web/20140701134751/http://www.pcm.com/n/Symantec-Softwares/manufacturers-14|archive-date=July 1, 2014}}SAM Identifies Virus-Infected Files, Repairs Applications, InfoWorld, May 22, 1989 SAM 2.0, released March 1990, incorporated technology allowing users to easily update SAM to intercept and eliminate new viruses, including many that didn't exist at the time of the program's release.SAM Update Lets Users Program for New Viruses, InfoWorld, February 19, 1990
In the end of the 1980s, in United Kingdom, Jan Hruska and Peter Lammer founded the security firm Sophos and began producing their first antivirus and encryption products. In the same period, in Hungary, VirusBuster was founded (and subsequently incorporated by Sophos).{{cite web |url=https://pitchbook.com/profiles/company/144629-92|title=VirusBuster Company Profile 2024: Valuation, Investors, Acquisition}}
= 1990–2000 period (emergence of the antivirus industry) =
In 1990, in Spain, Mikel Urizarbarrena founded Panda Security (Panda Software at the time).{{cite web
|url = http://www.gtts2012.com/panda-security/
|title = Panda Security
|first = Sharanya
|last = Naveen
|access-date = May 31, 2016
|url-status = dead
|archive-url = https://web.archive.org/web/20160630011311/http://www.gtts2012.com/panda-security/
|archive-date = June 30, 2016
|df = mdy-all
}} In Hungary, the security researcher Péter Szőr released the first version of Pasteur antivirus.
In 1990, the Computer Antivirus Research Organization (CARO) was founded. In 1991, CARO released the "Virus Naming Scheme", originally written by Friðrik Skúlason and Vesselin Bontchev.{{cite web|url=http://www.caro.org/articles/naming.html|title=A New Virus Naming Convention (1991) – CARO – Computer Antivirus Research Organization|url-status=live|archive-url=https://web.archive.org/web/20110813050343/http://caro.org/articles/naming.html|archive-date=August 13, 2011}} Although this naming scheme is now outdated, it remains the only existing standard that most computer security companies and researchers ever attempted to adopt. CARO members includes: Alan Solomon, Costin Raiu, Dmitry Gryaznov, Eugene Kaspersky, Friðrik Skúlason, Igor Muttik, Mikko Hyppönen, Morton Swimmer, Nick FitzGerald, Padgett Peterson, Peter Ferrie, Righard Zwienenberg and Vesselin Bontchev.{{cite web|title=CARO Members|url=http://www.caro.org/users/index.html|publisher=CARO|access-date=June 6, 2011|url-status=live|archive-url=https://web.archive.org/web/20110718173410/http://www.caro.org/users/index.html|archive-date=July 18, 2011}}[http://caro.org/users/igor.html CAROids, Hamburg 2003] {{webarchive |url=https://web.archive.org/web/20141107045334/http://caro.org/users/igor.html |date=November 7, 2014}}
In 1991, in the United States, Symantec released the first version of Norton AntiVirus. In the same year, in the Czech Republic, Jan Gritzbach and Tomáš Hofer founded AVG Technologies (Grisoft at the time), although they released the first version of their Anti-Virus Guard (AVG) only in 1992. On the other hand, in Finland, F-Secure (founded in 1988 by Petri Allas and Risto Siilasmaa – with the name of Data Fellows) released the first version of their antivirus product. F-Secure claims to be the first antivirus firm to establish a presence on the World Wide Web.{{cite web |url=http://www.f-secure.com/weblog/ |title=F-Secure Weblog : News from the Lab |publisher=F-secure.com |access-date=September 23, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120923084039/http://www.f-secure.com/weblog/ |archive-date=September 23, 2012}}
In 1991, the European Institute for Computer Antivirus Research (EICAR) was founded to further antivirus research and improve development of antivirus software.{{cite web|title=About EICAR|url=http://www.eicar.org/6-0-General-Info.html|work=EICAR official website|access-date=October 28, 2013|url-status=dead|archive-url=https://web.archive.org/web/20180614161636/http://www.eicar.org/6-0-General-Info.html|archive-date=June 14, 2018}}{{cite web|url= http://www.eset.com/resources/white-papers/AVAR-EICAR-2010.pdf |title=Test Files and Product Evaluation: the Case for and against Malware Simulation |first1=David|last1=Harley|first2=Lysa|last2=Myers|first3=Eddy|last3=Willems |work=AVAR2010 13th Association of anti Virus Asia Researchers International Conference |access-date=June 30, 2011|archive-url = https://web.archive.org/web/20110929040553/http://www.eset.com/resources/white-papers/AVAR-EICAR-2010.pdf |archive-date = September 29, 2011}}
In 1992, in Russia, Igor Danilov released the first version of SpiderWeb, which later became Dr.Web.{{cite web |url=http://www.reviewcentre.com/reviews95169.html |title=Dr. Web LTD Doctor Web / Dr. Web Reviews, Best AntiVirus Software Reviews, Review Centre |publisher=Reviewcentre.com |access-date=February 17, 2014 |url-status=live |archive-url=https://web.archive.org/web/20140223163636/http://www.reviewcentre.com/reviews95169.html |archive-date=February 23, 2014}}
In 1994, AV-TEST reported that there were 28,613 unique malware samples (based on MD5) in their database.[In 1994, AV-Test.org reported 28,613 unique malware samples (based on MD5). "A Brief History of Malware; The First 25 Years"]
Over time other companies were founded. In 1996, in Romania, Bitdefender was founded and released the first version of Anti-Virus eXpert (AVX).{{cite web|title=BitDefender Product History |url=http://www.bitdefender.co.uk/site/Main/view/product-history.html |url-status=dead |archive-url=https://web.archive.org/web/20120317052525/http://www.bitdefender.co.uk/site/Main/view/product-history.html |archive-date=March 17, 2012}} In 1997, in Russia, Eugene Kaspersky and Natalya Kaspersky co-founded security firm Kaspersky Lab.{{cite web|url=http://infowatch.com/company/management|title=InfoWatch Management|author=|publisher=InfoWatch|access-date=August 12, 2013|url-status=dead|archive-url=https://web.archive.org/web/20130821073955/http://infowatch.com/company/management|archive-date=August 21, 2013}}
In 1996, there was also the first "in the wild" Linux virus, known as "Staog".{{cite web|url=https://help.ubuntu.com/community/Linuxvirus|title=Linuxvirus – Community Help Wiki|url-status=live|archive-url=https://web.archive.org/web/20170324032340/https://help.ubuntu.com/community/Linuxvirus|archive-date=March 24, 2017}}
In 1999, AV-TEST reported that there were 98,428 unique malware samples (based on MD5) in their database.
= 2000–2005 period =
In 2000, Rainer Link and Howard Fuhs started the first open source antivirus engine, called OpenAntivirus Project.{{cite web|url=http://openantivirus.org|title=Sorry – recovering...|url-status=live|archive-url=https://web.archive.org/web/20140826133818/http://openantivirus.org/|archive-date=August 26, 2014}}
In 2001, Tomasz Kojm released the first version of ClamAV, the first ever open source antivirus engine to be commercialised. In 2007, ClamAV was bought by Sourcefire,{{cite web |url=http://www.clamav.org/2007/08/17/sourcefire-acquires-clamav/ |title=Sourcefire acquires ClamAV |publisher=ClamAV |date=August 17, 2007 |access-date=February 12, 2008 |url-status=dead |archive-url= https://web.archive.org/web/20071215031743/http://www.clamav.org/2007/08/17/sourcefire-acquires-clamav/ |archive-date=December 15, 2007}} which in turn was acquired by Cisco Systems in 2013.{{cite web| url=http://www.cisco.com/web/about/ac49/ac0/ac1/ac259/sourcefire.html| title=Cisco Completes Acquisition of Sourcefire| date=October 7, 2013| website=cisco.com| access-date=June 18, 2014| archive-url= https://web.archive.org/web/20150113145121/http://www.cisco.com/web/about/ac49/ac0/ac1/ac259/sourcefire.html |archive-date=January 13, 2015| url-status=live}}
In 2002, in United Kingdom, Morten Lund and Theis Søndergaard co-founded the antivirus firm BullGuard.[http://www.brandeins.de/magazin/bewegt-euch/der-unternehmer.html Der Unternehmer – brand eins online] {{webarchive|url=https://web.archive.org/web/20121122114224/http://www.brandeins.de/magazin/bewegt-euch/der-unternehmer.html |date=November 22, 2012}}. Brandeins.de (July 2009). Retrieved on January 3, 2017.
In 2005, AV-TEST reported that there were 333,425 unique malware samples (based on MD5) in their database.
= 2005–2014 period =
In 2007, AV-TEST reported a number of 5,490,960 new unique malware samples (based on MD5) only for that year. In 2012 and 2013, antivirus firms reported a new malware samples range from 300,000 to over 500,000 per day.{{cite magazine|title=The digital detective: Mikko Hypponen's war on malware is escalating |first=Greg |last=Williams |magazine=Wired |date=April 2012 |url=https://www.wired.co.uk/magazine/archive/2012/04/features/the-digital-detective |archive-url= https://web.archive.org/web/20160315051548/http://www.wired.co.uk/magazine/archive/2012/04/features/the-digital-detective |archive-date=March 15, 2016 |url-status=live}}{{cite web |url=http://www.ted.com/talks/james_lyne_everyday_cybercrime_and_what_you_can_do_about_it.html|title=Everyday cybercrime – and what you can do about it|date=September 16, 2013 |url-status=live |archive-url= https://web.archive.org/web/20140220062643/http://www.ted.com/talks/james_lyne_everyday_cybercrime_and_what_you_can_do_about_it.html |archive-date=February 20, 2014}}
Over the years it has become necessary for antivirus software to use several different strategies (e.g. specific email and network protection or low level modules) and detection algorithms, as well as to check an increasing variety of files, rather than just executables, for several reasons:
- Powerful macros used in word processor applications, such as Microsoft Word, presented a risk. Virus writers could use the macros to write viruses embedded within documents. This meant that computers could now also be at risk from infection by opening documents with hidden attached macros.{{sfn|Szor|2005|pp=66–67}}
- The possibility of embedding executable objects inside otherwise non-executable file formats can make opening those files a risk.{{cite web|url = http://news.cnet.com/2100-1001-271267.html|title = New virus travels in PDF files|access-date = October 29, 2011|date = August 7, 2001|url-status = live|archive-url = https://web.archive.org/web/20110616051806/http://news.cnet.com/2100-1001-271267.html|archive-date = June 16, 2011|df = mdy-all}}
- Later email programs, in particular Microsoft's Outlook Express and Outlook, were vulnerable to viruses embedded in the email body itself. A user's computer could be infected by just opening or previewing a message.{{cite web|url = http://www.slipstick.com/outlook/antivirus.htm|title = Protecting Microsoft Outlook against Viruses|access-date = June 18, 2009|last = Slipstick Systems|date=February 2009| archive-url= https://web.archive.org/web/20090602233638/http://www.slipstick.com/outlook/antivirus.htm| archive-date= June 2, 2009 | url-status= live}}
In 2005, F-Secure was the first security firm that developed an Anti-Rootkit technology, called BlackLight.
Because most users are usually connected to the Internet on a continual basis, Jon Oberheide first proposed a Cloud-based antivirus design in 2008.{{cite web|url=https://www.usenix.org/legacy/event/sec08/tech/full_papers/oberheide/oberheide_html/index.html|title=CloudAV: N-Version Antivirus in the Network Cloud|publisher=usenix.org|url-status=live|archive-url=https://web.archive.org/web/20140826115701/https://www.usenix.org/legacy/event/sec08/tech/full_papers/oberheide/oberheide_html/index.html|archive-date=August 26, 2014}}
In February 2008 McAfee Labs added the industry-first cloud-based anti-malware functionality to VirusScan under the name Artemis. It was tested by AV-Comparatives in February 2008[http://www.av-comparatives.org/wp-content/uploads/2008/01/sp_fdt_mcafee_200802_en.pdf McAfee Artemis Preview Report] {{webarchive|url=https://web.archive.org/web/20160403110306/http://www.av-comparatives.org/wp-content/uploads/2008/01/sp_fdt_mcafee_200802_en.pdf |date=April 3, 2016}}. av-comparatives.org and officially unveiled in August 2008 in McAfee VirusScan.[http://library.corporate-ir.net/library/10/104/104920/items/313409/MFEFQ308Oct30Final.pdf McAfee Third Quarter 2008] {{webarchive|url=https://web.archive.org/web/20160403020632/http://library.corporate-ir.net/library/10/104/104920/items/313409/MFEFQ308Oct30Final.pdf |date=April 3, 2016}}. corporate-ir.net
Cloud AV created problems for comparative testing of security software – part of the AV definitions was out of testers control (on constantly updated AV company servers) thus making results non-repeatable. As a result, Anti-Malware Testing Standards Organisation (AMTSO) started working on method of testing cloud products which was adopted on May 7, 2009.{{cite web |url=http://www.amtso.org/download/amtso-best-practices-for-testing-in-the-cloud-security-products|title=AMTSO Best Practices for Testing In-the-Cloud Security Products|publisher=AMTSO|url-status=dead |archive-url= https://web.archive.org/web/20160414175042/http://www.amtso.org/download/amtso-best-practices-for-testing-in-the-cloud-security-products/|archive-date=April 14, 2016|access-date=March 21, 2016}}
In 2011, AVG introduced a similar cloud service, called Protective Cloud Technology.{{cite web|url=http://www.avgsecurity.co.za/technology-overview |title=TECHNOLOGY OVERVIEW |website=AVG Security |access-date=February 16, 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150602055929/http://www.avgsecurity.co.za/technology-overview |archive-date=June 2, 2015}}
= 2014–present: rise of next-gen, market consolidation =
Following the 2013 release of the APT 1 report from Mandiant, the industry has seen a shift towards signature-less approaches to the problem capable of detecting and mitigating zero-day attacks.{{cite magazine|url=https://www.wired.com/story/mysterious-return-of-years-old-chinese-malware-apt1/|title=The Mysterious Return of Years-Old Chinese Malware|magazine=Wired|date=18 October 2018|access-date=16 June 2019|via=www.wired.com|last1=Barrett|first1=Brian}} Numerous approaches to address these new forms of threats have appeared, including behavioral detection, artificial intelligence, machine learning, and cloud-based file detection. According to Gartner, it is expected the rise of new entrants, such Carbon Black, Cylance and Crowdstrike will force end point protection incumbents into a new phase of innovation and acquisition.{{cite web|url=https://www.gartner.com/doc/reprints?id=1-2XXIZ8F|title=Magic Quadrant Endpoint Protection Platforms 2016|publisher=Gartner Research}}
One method from Bromium involves micro-virtualization to protect desktops from malicious code execution initiated by the end user. Another approach from SentinelOne and Carbon Black focuses on behavioral detection by building a full context around every process execution path in real time,{{cite web|url=http://www.networkworld.com/article/2466793/security0/start-up-offers-up-endpoint-detection-and-response-for-behavior-based-malware-detection.html|title=Start-up offers up endpoint detection and response for behavior-based malware detection|first=Ellen|last=Messmer|publisher=networkworld.com|url-status=live|archive-url=https://web.archive.org/web/20150205023309/http://www.networkworld.com/article/2466793/security0/start-up-offers-up-endpoint-detection-and-response-for-behavior-based-malware-detection.html|archive-date=February 5, 2015|date=2014-08-20}}{{cite web|url=http://www.hstoday.us/briefings/industry-news/single-article/bromium-research-reveals-insecurity-in-existing-endpoint-malware-protection-deployments/05ccfa234d62872b3d3a5422f2cbd4bd.html|title=Homeland Security Today: Bromium Research Reveals Insecurity in Existing Endpoint Malware Protection Deployments|url-status=live|archive-url=https://web.archive.org/web/20150924031641/http://www.hstoday.us/briefings/industry-news/single-article/bromium-research-reveals-insecurity-in-existing-endpoint-malware-protection-deployments/05ccfa234d62872b3d3a5422f2cbd4bd.html|archive-date=September 24, 2015}} while Cylance leverages an artificial intelligence model based on machine learning.{{Cite news|url=https://www.forbes.com/sites/thomasbrewster/2016/07/06/duelling-unicorns-crowdstrike-vs-cylance-in-brutal-battle-to-knock-hackers-out/#9cd0a3b12114|title=Duelling Unicorns: CrowdStrike Vs. Cylance In Brutal Battle To Knock Hackers Out|work=Forbes|date=July 6, 2016|url-status=live|archive-url=https://web.archive.org/web/20160911015121/http://www.forbes.com/sites/thomasbrewster/2016/07/06/duelling-unicorns-crowdstrike-vs-cylance-in-brutal-battle-to-knock-hackers-out/#9cd0a3b12114|archive-date=September 11, 2016}}
Increasingly, these signature-less approaches have been defined by the media and analyst firms as "next-generation" antivirus{{Cite news|url=http://thevarguy.com/blog/anti-virus-dead-shift-toward-next-gen-endpoints|title=Is Anti-virus Dead? The Shift Toward Next-Gen Endpoints|last=Potter|first=Davitt|date=June 9, 2016|url-status=usurped|archive-url=https://web.archive.org/web/20161220093921/http://thevarguy.com/blog/anti-virus-dead-shift-toward-next-gen-endpoints|archive-date=December 20, 2016}} and are seeing rapid market adoption as certified antivirus replacement technologies by firms such as Coalfire and DirectDefense.{{cite web|url=https://www.cylance.com/cylanceprotect-achieves-hipaa-security-rule-compliance-certification|title=CylancePROTECT® Achieves HIPAA Security Rule Compliance Certification|publisher=Cylance|url-status=dead|archive-url=https://web.archive.org/web/20161022023812/https://www.cylance.com/cylanceprotect-achieves-hipaa-security-rule-compliance-certification|archive-date=October 22, 2016|access-date=October 21, 2016}} In response, traditional antivirus vendors such as Trend Micro,{{cite web|url=http://www.trendmicro.com/us/business/xgen/index.html?cm_mmc=VURL:www.trendmicro.com-_-VURL-_-/xgen/index.html-_-vanity|title=Trend Micro-XGen|date=October 18, 2016|publisher=Trend Micro|url-status=live|archive-url=https://web.archive.org/web/20161221074459/http://www.trendmicro.com/us/business/xgen/index.html?cm_mmc=VURL%3Awww.trendmicro.com-_-VURL-_-%2Fxgen%2Findex.html-_-vanity|archive-date=December 21, 2016}} Symantec and Sophos{{cite web|url=https://www.sophos.com/en-us/products/endpoint-antivirus.aspx|title=Next-Gen Endpoint|publisher=Sophos|url-status=live|archive-url=https://web.archive.org/web/20161106204530/https://www.sophos.com/en-us/products/endpoint-antivirus.aspx|archive-date=November 6, 2016}} have responded by incorporating "next-gen" offerings into their portfolios as analyst firms such as Forrester and Gartner have called traditional signature-based antivirus "ineffective" and "outdated".[https://www.forrester.com/report/The+Forrester+Wave+Endpoint+Security+Suites+Q4+2016/-/E-RES113145 The Forrester Wave™: Endpoint Security Suites, Q4 2016] {{webarchive|url=https://web.archive.org/web/20161022024840/https://www.forrester.com/report/The+Forrester+Wave+Endpoint+Security+Suites+Q4+2016/-/E-RES113145 |date=October 22, 2016}}. Forrester.com (October 19, 2016). Retrieved on 2017-01-03.
As of Windows 8, Windows includes its own free antivirus protection under the Windows Defender brand. Despite bad detection scores in its early days, AV-Test now certifies Defender as one of its top products.{{Cite web |author1=Paul Wagenseil |date=2016-05-25 |title=Is Windows Defender Good Enough? Not Yet |url=https://www.tomsguide.com/us/avoid-windows-defender,news-22729.html |access-date=2023-12-18 |website=Tom's Guide |language=en}}{{Cite web |title=Test antivirus software for Windows 11 - October 2023 |url=https://www.av-test.org/en/antivirus/home-windows/ |access-date=2023-12-18 |website=www.av-test.org |language=en-US}} While it isn't publicly known how the inclusion of antivirus software in Windows affected antivirus sales, Google search traffic for antivirus has declined significantly since 2010.{{Cite web |title=Google Trends |url=https://trends.google.com/trends/explore?date=all&q=antivirus&hl=en |access-date=2023-12-18 |website=Google Trends |language=en-US |archive-date=December 18, 2023 |archive-url=https://web.archive.org/web/20231218123917/https://trends.google.com/trends/explore?date=all&q=antivirus&hl=en |url-status=dead }} In 2014 Microsoft bought McAfee.{{cite web|title=McAfee Becomes Intel Security|url=http://s927.t.en25.com/e/es.aspx?s=927&e=269752&elq=1610bb9546d14d169335d6b8d1b37f7c|publisher=McAfee Inc|access-date=January 15, 2014|archive-date=January 15, 2014|archive-url=https://archive.today/20140115034548/http://s927.t.en25.com/e/es.aspx?s=927&e=269752&elq=1610bb9546d14d169335d6b8d1b37f7c|url-status=dead}}
Since 2016, there has been a notable amount of consolidation in the industry. Avast purchased AVG in 2016 for $1.3 billion.{{Cite web |title=Avast Announces Agreement to Acquire AVG for $1.3B |url=https://press.avast.com/avast-announces-agreement-to-acquire-avg-for-13b |access-date=2023-12-18 |website=Avast Announces Agreement to Acquire AVG for $1.3B |language=en}} Avira was acquired by Norton owner Gen Digital (then NortonLifeLock) in 2020 for $360 million.{{Cite web |last=Lunden |first=Ingrid |date=2020-12-07 |title=NortonLifeLock acquires Avira in $360M all-cash deal, 8 months after Avira was acquired for $180M |url=https://techcrunch.com/2020/12/07/nortonlifelock-acquires-avira-in-360m-all-cash-deal-8-months-after-avira-was-acquired-for-180m/ |access-date=2023-12-18 |website=TechCrunch |language=en-US}} In 2021, the Avira division of Gen Digital acquired BullGuard.{{Cite web |author1=Daniel Todd |date=2022-02-07 |title=BullGuard to drop name in favour of Norton branding |url=https://www.itpro.com/business/business-strategy/367111/bullguard-to-drop-name-in-favour-of-norton-branding |access-date=2023-12-18 |website=channelpro |language=en}} The BullGuard brand was discontinued in 2022 and its customers were migrated to Norton. In 2022, Gen Digital acquired Avast, effectively consolidating four major antivirus brands under one owner.{{Cite web |title=NortonLifeLock Completes Merger with Avast |url=https://press.avast.com/nortonlifelock-completes-merger-with-avast |access-date=2023-12-18 |website=NortonLifeLock Completes Merger with Avast |language=en}}
In September 2024, following the US Commerce Department's ban on Kaspersky, Pango Group acquired its customers (about 1 million).{{Cite web |title=Kaspersky antivirus gets sold to U.S. firm Pango Group |url=https://www.axios.com/2024/09/05/kaspersky-pango-group-antivirus-deal |access-date=2025-05-14 |website=Axios |date=2024-09-05 |language=en}} The customers received continued services with no action required on their part. Then, in December 2024, Pango Group merged with Total Security, the provider of Total AV antivirus. The combined entity, now called Point Wild, has an enterprise value of $1.7 billion. {{Cite web |title=Pango Group Merges with Total Security; Combined Company Rebranded Point Wild |url=https://www.prnewswire.com/news-releases/pango-group-merges-with-total-security-combined-company-rebranded-point-wild-302330290.html |access-date=2025-05-14 |website=PR Newswire |date=2024-06-26 |language=en}}
As of 2024, more than half of Americans use built-in antivirus protection for their devices like Microsoft Defender or XProtect from Apple. However, about 121 million adults still use third-party antivirus software. Half of these adults use paid products, and about 50% of third-party software users - the owners of personal computers and Windows operating systems.{{Cite web |title=2024 Antivirus Trends, Statistics, and Merket Report |url=https://www.security.org/antivirus/antivirus-consumer-report-annual/ |url-status=live |archive-url=https://web.archive.org/web/20240717010707/https://www.security.org/antivirus/antivirus-consumer-report-annual/ |archive-date=2024-07-17 |access-date=2024-11-24 |website=Security.org |language=en}} Antivirus programs on mobile devices are used by 17% of adults.{{Cite web |title=2025 Antivirus Trends, Statistics, and Market Report |url=https://www.security.org/antivirus/antivirus-consumer-report-annual/ |access-date=2025-03-18 |website=Security.org |language=en-US}}
The 2025 antivirus market report confirms that most third-party antivirus users are on desktop devices, primarily aged between 35 and 45.{{Cite web |title=2025 antivirus market report: trends, stats and forecasts |url=https://cybernews.com/best-antivirus-software/antivirus-market-report/ |access-date=2025-05-14 |website=Cybernews |date=2025-04-22 |language=en}} In contrast, younger users (18–25) tend to rely on ad blockers instead.
Identification methods
In 1987, Frederick B. Cohen demonstrated that the algorithm which would be able to detect all possible viruses can't possibly exist (like the algorithm which determines whether or not the given program halts). However, using different layers of defense, a good detection rate may be achieved.
There are several methods which antivirus engines can use to identify malware:
- Sandbox detection: a particular behavioural-based detection technique that, instead of detecting the behavioural fingerprint at run time, it executes the programs in a virtual environment, logging what actions the program performs. Depending on the actions logged which can include memory usage and network accesses,{{Cite journal |last1=Lv |first1=Mingqi |last2=Zeng |first2=Huan |last3=Chen |first3=Tieming |last4=Zhu |first4=Tiantian |date=2023-10-01 |title=CTIMD: Cyber Threat Intelligence Enhanced Malware Detection Using API Call Sequences with Parameters |url=https://www.sciencedirect.com/science/article/pii/S0167404823004285 |journal=Computers & Security |volume=136 |pages=103518 |doi=10.1016/j.cose.2023.103518 |issn=0167-4048}} the antivirus engine can determine if the program is malicious or not.[https://enterprise.comodo.com/security-solutions/endpoint-protection/sandboxing.php Sandboxing Protects Endpoints | Stay Ahead Of Zero Day Threats] {{webarchive|url=https://web.archive.org/web/20150402115401/https://enterprise.comodo.com/security-solutions/endpoint-protection/sandboxing.php |date=April 2, 2015}}. Enterprise.comodo.com (June 20, 2014). Retrieved on 2017-01-03. If not, then, the program is executed in the real environment. Although this technique has shown to be quite effective, given its heaviness and slowness, it is rarely used in end-user antivirus solutions.{{sfn|Szor|2005|pp=474–481}}
- Data mining techniques: one of the latest approaches applied in malware detection. Data mining and machine learning algorithms are used to try to classify the behaviour of a file (as either malicious or benign) given a series of file features, that are extracted from the file itself.{{cite book|doi=10.1109/ACT.2010.33|chapter=Analysis of Machine learning Techniques Used in Behavior-Based Malware Detection|title=2010 Second International Conference on Advances in Computing, Control, and Telecommunication Technologies|page=201|year=2010|last1=Firdausi|first1=Ivan|last2=Lim|first2=Charles|last3=Erwin|first3=Alva|last4=Nugroho|first4=Anto Satriyo|isbn=978-1-4244-8746-2|s2cid=18522498}}{{cite book|doi=10.1109/SECPRI.2001.924286|chapter=Data mining methods for detection of new malicious executables|title=Proceedings 2001 IEEE Symposium on Security and Privacy. S&P 2001|page=38|year=2001|last1=Schultz|first1=M.G.|last2=Eskin|first2=E.|last3=Zadok|first3=F.|last4=Stolfo|first4=S.J.|isbn=978-0-7695-1046-0|citeseerx=10.1.1.408.5676|s2cid=21791}}{{cite journal|doi=10.1007/s10844-010-0148-x|title="Andromaly": A behavioral malware detection framework for android devices|journal=Journal of Intelligent Information Systems|volume=38|page=161|year=2011|last1=Shabtai|first1=Asaf|last2=Kanonov|first2=Uri|last3=Elovici|first3=Yuval|last4=Glezer|first4=Chanan|last5=Weiss|first5=Yael|s2cid=6993130}}
= Signature-based detection =
Traditional antivirus software relies heavily upon signatures to identify malware.{{cite web|last1=Fox-Brewster|first1=Thomas|title=Netflix Is Dumping Anti-Virus, Presages Death Of An Industry|url=https://www.forbes.com/sites/thomasbrewster/2015/08/26/netflix-and-death-of-anti-virus/|work=Forbes|access-date=September 4, 2015|url-status=live|archive-url=https://web.archive.org/web/20150906134903/http://www.forbes.com/sites/thomasbrewster/2015/08/26/netflix-and-death-of-anti-virus/|archive-date=September 6, 2015}}
Substantially, when a malware sample arrives in the hands of an antivirus firm, it is analysed by malware researchers or by dynamic analysis systems. Then, once it is determined to be a malware, a proper signature of the file is extracted and added to the signatures database of the antivirus software.[https://chschulte.github.io/teaching/theses/ICT-ECS-2006-122.pdf Automatic Malware Signature Generation] {{webarchive|url=https://web.archive.org/web/20210124224753/https://chschulte.github.io/teaching/theses/ICT-ECS-2006-122.pdf|date=January 24, 2021}}. (PDF) . Retrieved on January 3, 2017.
Although the signature-based approach can effectively contain malware outbreaks, malware authors have tried to stay a step ahead of such software by writing "oligomorphic", "polymorphic" and, more recently, "metamorphic" viruses, which encrypt parts of themselves or otherwise modify themselves as a method of disguise, so as to not match virus signatures in the dictionary.{{sfn|Szor|2005|pp=252–288}}
= Heuristics =
Many viruses start as a single infection and through either mutation or refinements by other attackers, can grow into dozens of slightly different strains, called variants. Generic detection refers to the detection and removal of multiple threats using a single virus definition.{{cite web |url=http://www.securelist.com/en/glossary?glossid=189210517 |title=Generic detection |access-date=July 11, 2013 |publisher=Kaspersky |url-status=dead |archive-url=https://web.archive.org/web/20131203013651/http://www.securelist.com/en/glossary?glossid=189210517 |archive-date=December 3, 2013}}
For example, the Vundo trojan has several family members, depending on the antivirus vendor's classification. Symantec classifies members of the Vundo family into two distinct categories, Trojan.Vundo and Trojan.Vundo.B.{{cite web|url = http://www.symantec.com/security_response/writeup.jsp?docid=2004-112111-3912-99|title = Trojan.Vundo|access-date = April 14, 2009|last = Symantec Corporation|date=February 2009| archive-url= https://web.archive.org/web/20090409002645/http://www.symantec.com/security_response/writeup.jsp?docid=2004-112111-3912-99| archive-date= April 9, 2009 | url-status= dead}}{{cite web|url = http://www.symantec.com/security_response/writeup.jsp?docid=2005-042810-2611-99|title = Trojan.Vundo.B|access-date = April 14, 2009|last = Symantec Corporation|date=February 2007| archive-url= https://web.archive.org/web/20090427160747/http://www.symantec.com/security_response/writeup.jsp?docid=2005-042810-2611-99| archive-date= April 27, 2009 | url-status= dead}}
While it may be advantageous to identify a specific virus, it can be quicker to detect a virus family through a generic signature or through an inexact match to an existing signature. Virus researchers find common areas that all viruses in a family share uniquely and can thus create a single generic signature. These signatures often contain non-contiguous code, using wildcard characters where differences lie. These wildcards allow the scanner to detect viruses even if they are padded with extra, meaningless code.{{cite web|url=http://www.extremetech.com/article2/0,2845,1154648,00.asp |title=Antivirus Research and Detection Techniques |access-date=February 24, 2009 |publisher=ExtremeTech |archive-url=https://web.archive.org/web/20090227002351/http://www.extremetech.com/article2/0%2C2845%2C1154648%2C00.asp |archive-date=February 27, 2009 |url-status=live}} A detection that uses this method is said to be "heuristic detection".
= Rootkit detection =
{{Main|Rootkit}}
Anti-virus software can attempt to scan for rootkits. A rootkit is a type of malware designed to gain administrative-level control over a computer system without being detected. Rootkits can change how the operating system functions and in some cases can tamper with the anti-virus program and render it ineffective. Rootkits are also difficult to remove, in some cases requiring a complete re-installation of the operating system.{{cite web|url=http://www.f-secure.com/en_EMEA/security/virus-removal/virus-information/encyclopedia/encyclopedia_rootkit.html|title=Terminology – F-Secure Labs|url-status=live |archive-url= https://web.archive.org/web/20100824081556/http://www.f-secure.com/en_EMEA/security/virus-removal/virus-information/encyclopedia/encyclopedia_rootkit.html|archive-date=August 24, 2010}}
= Real-time protection =
Real-time protection, on-access scanning, background guard, resident shield, autoprotect, and other synonyms refer to the automatic protection provided by most antivirus, anti-spyware, and other anti-malware programs. This monitors computer systems for suspicious activity such as computer viruses, spyware, adware, and other malicious objects. Real-time protection detects threats in opened files and scans apps in real-time as they are installed on the device.{{Cite web|title=Real-Time Protection|url=https://support.kaspersky.com/KISA/MR21/en-us/71782.htm|access-date=2021-04-09|website=support.kaspersky.com}} When inserting a CD, opening an email, or browsing the web, or when a file already on the computer is opened or executed.{{Cite web|url=https://usa.kaspersky.com/|archiveurl=https://web.archive.org/web/20060312194238/http://www.kaspersky.com/faq?chapter=170710015&qid=173727547|url-status=dead|title=Kaspersky Cyber Security Solutions for Home & Business | Kaspersky|archivedate=March 12, 2006|website=usa.kaspersky.com}}
Issues of concern
= Unexpected renewal costs =
Some commercial antivirus software end-user license agreements include a clause that the subscription will be automatically renewed, and the purchaser's credit card automatically billed, at the renewal time without explicit approval. For example, McAfee requires users to unsubscribe at least 60 days before the expiration of the present subscription,{{cite web|url = http://michaelkelly.blogs.com/buyingdangerously/2006/10/bad_mcafee_on_a.html|title = Buying Dangerously|access-date = November 29, 2009|last = Kelly|first = Michael|date = October 2006|url-status = live|archive-url = https://web.archive.org/web/20100715083435/http://michaelkelly.blogs.com/buyingdangerously/2006/10/bad_mcafee_on_a.html|archive-date = July 15, 2010|df = mdy-all}} while Bitdefender sends notifications to unsubscribe 30 days before the renewal.{{cite web|url = http://www.bitdefender.com/site/KnowledgeBase/consumer/#542|title = Automatic Renewal|access-date = November 29, 2009|last = Bitdefender|year = 2009|url-status = live|archive-url = https://web.archive.org/web/20091006024635/http://www.bitdefender.com/site/knowledgebase/consumer#542|archive-date = October 6, 2009|df = mdy-all}} Norton AntiVirus also renews subscriptions automatically by default.{{cite web|url = https://support.norton.com/sp/en/uk/home/current/solutions/kb20080417115558EN_EndUserProfile_en_us|title = Norton Automatic Renewal Service FAQ|access-date = April 9, 2014|last = Symantec|year = 2014|url-status = live|archive-url = https://web.archive.org/web/20140413154605/https://support.norton.com/sp/en/uk/home/current/solutions/kb20080417115558EN_EndUserProfile_en_us|archive-date = April 13, 2014|df = mdy-all}}
= Rogue security applications =
{{main|Rogue security software}}
Some apparent antivirus programs are actually malware masquerading as legitimate software, such as WinFixer, MS Antivirus, and Mac Defender.{{cite web|url = http://www.spywarewarrior.com/rogue_anti-spyware.htm|title = Rogue/Suspect Anti-Spyware Products & Web Sites|access-date = November 29, 2009 |last = SpywareWarrior |year = 2007}}
= Problems caused by false positives =
A "false positive" or "false alarm" is when antivirus software identifies a non-malicious file as malware. When this happens, it can cause serious problems. For example, if an antivirus program is configured to immediately delete or quarantine infected files, as is common on Microsoft Windows antivirus applications, a false positive in an essential file can render the Windows operating system or some applications unusable.{{cite web |url=https://arstechnica.com/microsoft/news/2008/11/avg-incorrectly-flags-user32-dll-in-windows-xp-sp2sp3.ars|title=AVG incorrectly flags user32.dll in Windows XP SP2/SP3 |access-date=February 24, 2011|author=Protalinski, Emil |date=November 11, 2008|work=Ars Technica|url-status=live|archive-url=https://web.archive.org/web/20110430104824/http://arstechnica.com/microsoft/news/2008/11/avg-incorrectly-flags-user32-dll-in-windows-xp-sp2sp3.ars |archive-date=April 30, 2011}} Recovering from such damage to critical software infrastructure incurs technical support costs and businesses can be forced to close whilst remedial action is undertaken.{{cite web |url=http://www.zdnet.co.uk/news/security-management/2010/04/27/mcafee-to-compensate-businesses-for-buggy-update-40088779/|title=McAfee to compensate businesses for buggy update|access-date=December 2, 2010|url-status=live |archive-url=https://web.archive.org/web/20100904042440/http://www.zdnet.co.uk/news/security-management/2010/04/27/mcafee-to-compensate-businesses-for-buggy-update-40088779/|archive-date=September 4, 2010}}{{cite web |url=http://news.cnet.com/8301-1009_3-20003074-83.html|title=Buggy McAfee update whacks Windows XP PCs|work=CNET |access-date=December 2, 2010| archive-url= https://web.archive.org/web/20110113170013/http://news.cnet.com/8301-1009_3-20003074-83.html| archive-date= January 13, 2011 | url-status= live}}
Examples of serious false-positives:
- May 2007: a faulty virus signature issued by Symantec mistakenly removed essential operating system files, leaving thousands of PCs unable to boot.{{cite web|title=Flawed Symantec update cripples Chinese PCs|url=http://news.cnet.com/Flawed-Symantec-update-cripples-Chinese-PCs/2100-1002_3-6186271.html|author=Tan, Aaron|work=CNET Networks|date=May 24, 2007|access-date=April 5, 2009|url-status=live|archive-url=https://web.archive.org/web/20110426024703/http://news.cnet.com/Flawed-Symantec-update-cripples-Chinese-PCs/2100-1002_3-6186271.html|archive-date=April 26, 2011}}
- May 2007: the executable file required by Pegasus Mail on Windows was falsely detected by Norton AntiVirus as being a Trojan and it was automatically removed, preventing Pegasus Mail from running. Norton AntiVirus had falsely identified three releases of Pegasus Mail as malware, and would delete the Pegasus Mail installer file when that happened.{{cite web|url=http://www.pmail.com/v45x.htm|title=January 2010 – Pegasus Mail v4.52 Release|access-date=May 21, 2010|author=Harris, David |date=June 29, 2009|work=Pegasus Mail| archive-url= https://web.archive.org/web/20100528053020/http://www.pmail.com/v45x.htm| archive-date= May 28, 2010 | url-status= live}} In response to this Pegasus Mail stated:
:: {{cquote|On the basis that Norton/Symantec has done this for every one of the last three releases of Pegasus Mail, we can only condemn this product as too flawed to use, and recommend in the strongest terms that our users cease using it in favour of alternative, less buggy anti-virus packages.}}
- April 2010: McAfee VirusScan detected svchost.exe, a normal Windows binary, as a virus on machines running Windows XP with Service Pack 3, causing a reboot loop and loss of all network access.{{cite news|url=http://isc.sans.org/diary.html?storyid=8656|title=McAfee DAT 5958 Update Issues|date=April 21, 2010|access-date=April 22, 2010| archive-url= https://web.archive.org/web/20100424193336/http://isc.sans.org/diary.html?storyid=8656| archive-date= April 24, 2010 | url-status= live}}{{cite news|url=https://www.engadget.com/2010/04/21/mcafee-update--shutting-down-xp-machines/|title=Botched McAfee update shutting down corporate XP machines worldwide|date=April 21, 2010|access-date=April 22, 2010| archive-url= https://web.archive.org/web/20100422205355/http://www.engadget.com/2010/04/21/mcafee-update--shutting-down-xp-machines/| archive-date= April 22, 2010 | url-status= live}}
- December 2010: a faulty update on the AVG anti-virus suite damaged 64-bit versions of Windows 7, rendering it unable to boot, due to an endless boot loop created.{{cite web|url=https://www.theregister.co.uk/2010/12/02/avg_auto_immune_update/|title=Horror AVG update ballsup bricks Windows 7|author=Leyden, John|work=The Register|access-date=December 2, 2010|date=December 2, 2010|url-status=live|archive-url=https://web.archive.org/web/20101205043730/http://www.theregister.co.uk/2010/12/02/avg_auto_immune_update/|archive-date=December 5, 2010}}
- October 2011: Microsoft Security Essentials (MSE) removed the Google Chrome web browser, rival to Microsoft's own Internet Explorer. MSE flagged Chrome as a Zbot banking trojan.{{citation|url=http://www.theinquirer.net/inquirer/news/2113892/mse-false-positive-detection-forces-google-update-chrome|title=MSE false positive detection forces Google to update Chrome|access-date=October 3, 2011|url-status=unfit|archive-url=https://web.archive.org/web/20111004035408/http://www.theinquirer.net/inquirer/news/2113892/mse-false-positive-detection-forces-google-update-chrome|archive-date=October 4, 2011|date=2011-10-03}}
- September 2012: Sophos' anti-virus suite identified various update-mechanisms, including its own, as malware. If it was configured to automatically delete detected files, Sophos Antivirus could render itself unable to update, required manual intervention to fix the problem.{{citation|url=https://thenextweb.com/insider/2012/09/20/sophos-antimalware-software-detects-malware-deletes-critical-binaries/|title=Sophos Antivirus Detects Itself as Malware, Deletes Key Binaries|publisher=The Next Web|access-date=March 5, 2014|url-status=live|archive-url=https://web.archive.org/web/20140117032235/http://thenextweb.com/insider/2012/09/20/sophos-antimalware-software-detects-malware-deletes-critical-binaries/|archive-date=January 17, 2014|date=2012-09-20}}{{citation|url=http://nakedsecurity.sophos.com/2012/09/19/sshupdater-b-fsophos-anti-virus-products/|title=Shh/Updater-B false positive by Sophos anti-virus products|publisher=Sophos|access-date=March 5, 2014|url-status=live|archive-url=https://web.archive.org/web/20140421075501/http://nakedsecurity.sophos.com/2012/09/19/sshupdater-b-fsophos-anti-virus-products/|archive-date=April 21, 2014|date=2012-09-19}}
- September 2017: the Google Play Protect anti-virus started identifying Motorola's Moto G4 Bluetooth application as malware, causing Bluetooth functionality to become disabled.{{citation|url=http://www.androidpolice.com/2017/09/11/google-play-protect-breaking-bluetooth-moto-g4-plus-dont-worry-theres-fix/|title=If Google Play Protect is breaking bluetooth on your Moto G4 Plus, don't worry because there's a fix|publisher=Android Police|access-date=November 1, 2017|url-status=live|archive-url=https://web.archive.org/web/20171107020413/http://www.androidpolice.com/2017/09/11/google-play-protect-breaking-bluetooth-moto-g4-plus-dont-worry-theres-fix/|archive-date=November 7, 2017|date=2017-09-11}}
- September 2022: Microsoft Defender flagged all Chromium based web browsers and Electron based apps like WhatsApp, Discord, Spotify as a severe threat.{{citation|url=https://www.windowscentral.com/software-apps/windows-11/windows-defender-is-reporting-a-false-positive-threat-behaviorwin32hivezy-its-nothing-to-be-worried-about|title=Windows Defender is reporting a false-positive threat 'Behavior:Win32/Hive.ZY'; it's nothing to be worried about|publisher=Windows Central|access-date=September 5, 2012|url-status=live|archive-url=https://web.archive.org/web/20220905082109/https://www.windowscentral.com/software-apps/windows-11/windows-defender-is-reporting-a-false-positive-threat-behaviorwin32hivezy-its-nothing-to-be-worried-about|archive-date=September 5, 2022|date=2022-09-05}}
=Effectiveness=
Studies in December 2007 showed that the effectiveness of antivirus software had decreased in the previous year, particularly against unknown or zero day attacks. The computer magazine c't found that detection rates for these threats had dropped from 40 to 50% in 2006 to 20–30% in 2007. At that time, the only exception was the NOD32 antivirus, which managed a detection rate of 68%.{{cite web|work=Channel Register|url=http://www.channelregister.co.uk/2007/12/21/dwindling_antivirus_protection/|author=Goodin, Dan|title=Anti-virus protection gets worse|date=December 21, 2007|access-date=February 24, 2011|url-status=live|archive-url=https://web.archive.org/web/20110511081703/http://www.channelregister.co.uk/2007/12/21/dwindling_antivirus_protection/|archive-date=May 11, 2011}} According to the ZeuS tracker website the average detection rate for all variants of the ZeuS trojan is as low as 40%.{{cite web|url=https://zeustracker.abuse.ch/|title=ZeuS Tracker :: Home|url-status=live|archive-url=https://web.archive.org/web/20101103103725/https://zeustracker.abuse.ch/|archive-date=November 3, 2010}}{{third-party source needed|date=February 2025}}
The problem is magnified by the changing intent of virus authors. Some years ago it was obvious when a virus infection was present. At the time, viruses were written by amateurs and exhibited destructive behavior or pop-ups. Modern viruses are often written by professionals, financed by criminal organizations.{{cite web|url=http://www.computerweekly.com/Articles/2007/07/13/225537/hacking-poses-threats-to-business.htm|title=Hacking poses threats to business|access-date=November 15, 2009|author=Illett, Dan|work=Computer Weekly|date=July 13, 2007|url-status=live|archive-url=https://web.archive.org/web/20100112104421/http://www.computerweekly.com/Articles/2007/07/13/225537/hacking-poses-threats-to-business.htm|archive-date=January 12, 2010}}
In 2008, Eva Chen, CEO of Trend Micro, stated that the anti-virus industry has over-hyped how effective its products are—and so has been misleading customers—for years.{{cite web|url=https://www.zdnet.com/article/trend-micro-antivirus-industry-lied-for-20-years/|title=Trend Micro: Antivirus industry lied for 20 years|access-date=September 27, 2014|author=Espiner, Tom|work=ZDNet|date=June 30, 2008|url-status=live|archive-url=https://web.archive.org/web/20141006084845/http://www.zdnet.com/trend-micro-antivirus-industry-lied-for-20-years-3039440184/|archive-date=October 6, 2014}}
Independent testing on all the major virus scanners consistently shows that none provides 100% virus detection. The best ones provided as high as 99.9% detection for simulated real-world situations, while the lowest provided 91.1% in tests conducted in August 2013. Many virus scanners produce false positive results as well, identifying benign files as malware.{{cite web|url = http://www.av-comparatives.org/wp-content/uploads/2013/12/avc_prot_2013b_en.pdf|title = Whole Product Dynamic "Real World" Production Test |access-date = January 2, 2014|last = AV Comparatives |date=December 2013| archive-url= https://web.archive.org/web/20140102214834/http://www.av-comparatives.org/wp-content/uploads/2013/12/avc_prot_2013b_en.pdf| archive-date= January 2, 2014 | url-status= live}}
Although methods may differ, some notable independent quality testing agencies include AV-Comparatives, ICSA Labs, SE Labs, West Coast Labs, Virus Bulletin, AV-TEST and other members of the Anti-Malware Testing Standards Organization.{{cite web|url=http://www.computerworld.com/s/article/9178037/Guidelines_released_for_antivirus_software_tests|title=Guidelines released for antivirus software tests|first=Jeremy|last=Kirk|work=Computerworld |url-status=live|archive-url=https://web.archive.org/web/20110422121009/http://www.computerworld.com/s/article/9178037/Guidelines_released_for_antivirus_software_tests|archive-date=April 22, 2011|date=2010-06-14}}{{cite book |last= Harley |first= David |author-link= David Harley |title= AVIEN Malware Defense Guide for the Enterprise |url= https://books.google.com/books?id=LBzXf0A-jQwC |year= 2011 |publisher= Elsevier |isbn= 9780080558660 |page= 487 |url-status= live |archive-url= https://web.archive.org/web/20140103121250/http://books.google.com/books?id=LBzXf0A-jQwC |archive-date= January 3, 2014}}
=New viruses=
Anti-virus programs are not always effective against new viruses, even those that use non-signature-based methods that should detect new viruses. The reason for this is that the virus designers test their new viruses on the major anti-virus applications to make sure that they are not detected before releasing them into the wild.{{cite web|url = https://www.zdnet.com/article/why-popular-antivirus-apps-do-not-work/|title = Why popular antivirus apps 'do not work'|access-date = April 14, 2010|last = Kotadia|first = Munir| website=ZDNet |date = July 2006|url-status = live|archive-url = https://web.archive.org/web/20110430230447/http://www.zdnet.com.au/why-popular-antivirus-apps-do-not-work-139264249.htm?omnRef=NULL|archive-date = April 30, 2011|df = mdy-all}}
Some new viruses, particularly ransomware, use polymorphic code to avoid detection by virus scanners. Jerome Segura, a security analyst with ParetoLogic, explained:{{cite news|url = https://www.cbc.ca/news/internet-scam-uses-adult-game-to-extort-cash-1.964721|title = Internet scam uses adult game to extort cash|access-date = April 17, 2010|last = The Canadian Press |date=April 2010 | work=CBC News| archive-url= https://web.archive.org/web/20100418215458/http://www.cbc.ca/consumer/story/2010/04/16/con-adult-video-virus.html| archive-date= April 18, 2010 | url-status= live}}
{{cquote|It's something that they miss a lot of the time because this type of [ransomware virus] comes from sites that use a polymorphism, which means they basically randomize the file they send you and it gets by well-known antivirus products very easily. I've seen people firsthand getting infected, having all the pop-ups and yet they have antivirus software running and it's not detecting anything. It actually can be pretty hard to get rid of, as well, and you're never really sure if it's really gone. When we see something like that usually we advise to reinstall the operating system or reinstall backups.}}
A proof of concept virus has used the Graphics Processing Unit (GPU) to avoid detection from anti-virus software. The potential success of this involves bypassing the CPU in order to make it much harder for security researchers to analyse the inner workings of such malware.{{cite web|url=https://www.theregister.co.uk/2010/09/28/gpu_assisted_malware/|title=Researchers up evilness ante with GPU-assisted malware|website=The Register|url-status=live|archive-url=https://web.archive.org/web/20170810133923/https://www.theregister.co.uk/2010/09/28/gpu_assisted_malware/|archive-date=August 10, 2017}}
= Rootkits =
Detecting rootkits is a major challenge for anti-virus programs. Rootkits have full administrative access to the computer and are invisible to users and hidden from the list of running processes in the task manager. Rootkits can modify the inner workings of the operating system and tamper with antivirus programs.{{cite web|last1=Iresh|first1=Gina|title=Review of Bitdefender Antivirus Security Software 2017 edition|url=http://www.digitalgrog.com.au/software/how-to-secure-your-desktop-and-laptop-with-antivirus-software/|website=www.digitalgrog.com.au|publisher=Digital Grog|access-date=November 20, 2016|date=April 10, 2010|url-status=live|archive-url=https://web.archive.org/web/20161121165615/http://www.digitalgrog.com.au/software/how-to-secure-your-desktop-and-laptop-with-antivirus-software/|archive-date=November 21, 2016}}
= Damaged files =
If a file has been infected by a computer virus, anti-virus software will attempt to remove the virus code from the file during disinfection, but it is not always able to restore the file to its undamaged state.{{cite web|url=http://www.f-prot.com/support/windows/fpwin_faq/324.html|title=Why F-PROT Antivirus fails to disinfect the virus on my computer?|access-date=August 20, 2015|url-status=live|archive-url=https://web.archive.org/web/20150917003044/http://www.f-prot.com/support/windows/fpwin_faq/324.html|archive-date=September 17, 2015}}{{cite web|url=http://latam.kaspersky.com/knowledge-base-article/1526|title=Actions to be performed on infected objects|access-date=August 20, 2015|url-status=live|archive-url=https://web.archive.org/web/20150809113716/http://latam.kaspersky.com/knowledge-base-article/1526|archive-date=August 9, 2015}} In such circumstances, damaged files can only be restored from existing backups or shadow copies (this is also true for ransomware{{cite web|url=http://blog.malwarebytes.org/intelligence/2013/10/cryptolocker-ransomware-what-you-need-to-know/|title=Cryptolocker Ransomware: What You Need To Know|access-date=March 28, 2014|url-status=live|archive-url=https://web.archive.org/web/20140209084114/http://blog.malwarebytes.org/intelligence/2013/10/cryptolocker-ransomware-what-you-need-to-know/|archive-date=February 9, 2014|date=2013-10-08}}); installed software that is damaged requires re-installation{{cite web|url=http://www-cs-faculty.stanford.edu/~eroberts/cs201/projects/viruses/anti-virus.html|title=How Anti-Virus Software Works|access-date=February 16, 2011|url-status=live|archive-url=https://web.archive.org/web/20110302064000/http://www-cs-faculty.stanford.edu/~eroberts/cs201/projects/viruses/anti-virus.html|archive-date=March 2, 2011}} (however, see System File Checker).
= Firmware infections =
Any writeable firmware in the computer can be infected by malicious code.{{cite web|url=http://www.techrepublic.com/blog/10things/the-10-faces-of-computer-malware/881|title=The 10 faces of computer malware|access-date=March 6, 2011|date=July 17, 2009|url-status=live|archive-url=https://web.archive.org/web/20110209204847/http://www.techrepublic.com/blog/10things/the-10-faces-of-computer-malware/881|archive-date=February 9, 2011}} This is a major concern, as an infected BIOS could require the actual BIOS chip to be replaced to ensure the malicious code is completely removed.{{cite web|url=http://www.tomshardware.co.uk/bios-virus-rootkit-security-backdoor,news-30759.html|title=New BIOS Virus Withstands HDD Wipes|work=Tom's Hardware |access-date=March 6, 2011|date=March 27, 2009|url-status=live|archive-url=https://web.archive.org/web/20110401185956/http://www.tomshardware.co.uk/bios-virus-rootkit-security-backdoor,news-30759.html|archive-date=April 1, 2011}} Anti-virus software is not effective at protecting firmware and the motherboard BIOS from infection.{{cite web|url=http://www.phrack.com/archives/66/p66_0x07_Persistent%20BIOS%20infection_by_aLS%20and%20Alfredo.txt|title=Phrack Inc. Persistent BIOS Infection|access-date=March 6, 2011|date=June 1, 2009|archive-url = https://web.archive.org/web/20110430213042/http://www.phrack.com/archives/66/p66_0x07_Persistent%20BIOS%20infection_by_aLS%20and%20Alfredo.txt |archive-date = April 30, 2011}} In 2014, security researchers discovered that USB devices contain writeable firmware which can be modified with malicious code (dubbed "BadUSB"), which anti-virus software cannot detect or prevent. The malicious code can run undetected on the computer and could even infect the operating system prior to it booting up.{{cite web|url=https://srlabs.de/badusb/|title=Turning USB peripherals into BadUSB|access-date=October 11, 2014|url-status=live|archive-url=https://web.archive.org/web/20160418134155/https://srlabs.de/badusb/|archive-date=April 18, 2016}}{{cite magazine|url=https://www.wired.com/2014/07/usb-security/|title=Why the Security of USB Is Fundamentally Broken|magazine=Wired|date=July 31, 2014|access-date=October 11, 2014|url-status=live|archive-url=https://web.archive.org/web/20140803200841/http://www.wired.com/2014/07/usb-security/|archive-date=August 3, 2014|last1=Greenberg|first1=Andy}}
Performance and other drawbacks
Antivirus software has some drawbacks, first of which that it can impact a computer's performance.{{cite web|title=How Antivirus Software Can Slow Down Your Computer |url=http://www.support.com/blog/post/how-antivirus-software-can-slow-down-your-computer |publisher=Support.com Blog |access-date=July 26, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20120929003659/http://www.support.com/blog/post/how-antivirus-software-can-slow-down-your-computer |archive-date=September 29, 2012}}
Furthermore, inexperienced users can be lulled into a false sense of security when using the computer, considering their computers to be invulnerable, and may have problems understanding the prompts and decisions that antivirus software presents them with. An incorrect decision may lead to a security breach. If the antivirus software employs heuristic detection, it must be fine-tuned to minimize misidentifying harmless software as malicious (false positive).{{cite web | title=Softpedia Exclusive Interview: Avira 10 | url=http://news.softpedia.com/news/Avira-s-New-Anti-Malware-Fleet-139829.shtml | work=Ionut Ilascu | publisher=Softpedia | date=April 14, 2010 | access-date=September 11, 2011 | url-status=live | archive-url=https://web.archive.org/web/20110826154924/http://news.softpedia.com/news/Avira-s-New-Anti-Malware-Fleet-139829.shtml | archive-date=August 26, 2011}}
Antivirus software itself usually runs at the highly trusted kernel level of the operating system to allow it access to all the potential malicious process and files, creating a potential avenue of attack.{{cite web | title=Norton AntiVirus ignores malicious WMI instructions | url=https://www.zdnet.com/article/norton-antivirus-ignores-malicious-wmi-instructions/ | work=Munir Kotadia | publisher=CBS Interactive | date=October 21, 2004 | access-date=April 5, 2009 | url-status=live | archive-url=https://web.archive.org/web/20090912083538/http://www.zdnet.com.au/news/security/soa/Norton-AntiVirus-ignores-malicious-WMI-instructions/0,130061744,139163678,00.htm | archive-date=September 12, 2009}} The US National Security Agency (NSA) and the UK Government Communications Headquarters (GCHQ) intelligence agencies,
respectively, have been exploiting anti-virus software to spy on users.{{cite news| title=NSA and GCHQ attacked antivirus software so that they could spy on people, leaks indicate | url=http://www.belfasttelegraph.co.uk/technology/nsa-and-gchq-attacked-antivirus-software-so-that-they-could-spy-on-people-leaks-indicate-31327280.html | date=June 24, 2015 | access-date=October 30, 2016}} Anti-virus software has highly privileged and trusted access to the underlying operating system, which makes it a much more appealing target for remote attacks.{{cite web | url=https://theintercept.com/2015/06/22/nsa-gchq-targeted-kaspersky/ | title=Popular security software came under relentless NSA and GCHQ attacks | work=Andrew Fishman, Morgan Marquis-Boire | date=June 22, 2015 | access-date=October 30, 2016 | url-status=live | archive-url=https://web.archive.org/web/20161031151320/https://theintercept.com/2015/06/22/nsa-gchq-targeted-kaspersky/ | archive-date=October 31, 2016}} Additionally anti-virus software is "years behind security-conscious client-side applications like browsers or document readers. It means that Acrobat Reader, Microsoft Word or Google Chrome are harder to exploit than 90 percent of the anti-virus products out there", according to Joxean Koret, a researcher with Coseinc, a Singapore-based information security consultancy.
Alternative solutions
File:ClamAV0.95.2.png running a virus signature definition update, scanning a file, and identifying a Trojan]]
Antivirus software running on individual computers is the most common method employed of guarding against malware, but it is not the only solution. Other solutions can also be employed by users, including Unified Threat Management (UTM), hardware and network firewalls, Cloud-based antivirus and online scanners.
= Hardware and network firewall =
Network firewalls prevent unknown programs and processes from accessing the system. However, they are not antivirus systems and make no attempt to identify or remove anything. They may protect against infection from outside the protected computer or network, and limit the activity of any malicious software which is present by blocking incoming or outgoing requests on certain TCP/IP ports. A firewall is designed to deal with broader system threats that come from network connections into the system and is not an alternative to a virus protection system.
= Cloud antivirus =
Cloud antivirus is a technology that uses lightweight agent software on the protected computer, while offloading the majority of data analysis to the provider's infrastructure.{{cite web|url = http://blog.zeltser.com/post/1256199682/what-is-cloud-anti-virus|title = What Is Cloud Anti-Virus and How Does It Work?|access-date = October 26, 2010|last = Zeltser|first = Lenny|date=October 2010| archive-url= https://web.archive.org/web/20101010113820/http://blog.zeltser.com/post/1256199682/what-is-cloud-anti-virus| archive-date= October 10, 2010 | url-status= live}}
One approach to implementing cloud antivirus involves scanning suspicious files using multiple antivirus engines. This approach was proposed by an early implementation of the cloud antivirus concept called CloudAV. CloudAV was designed to send programs or documents to a network cloud where multiple antivirus and behavioral detection programs are used simultaneously in order to improve detection rates. Parallel scanning of files using potentially incompatible antivirus scanners is achieved by spawning a virtual machine per detection engine and therefore eliminating any possible issues. CloudAV can also perform "retrospective detection", whereby the cloud detection engine rescans all files in its file access history when a new threat is identified thus improving new threat detection speed. Finally, CloudAV is a solution for effective virus scanning on devices that lack the computing power to perform the scans themselves.{{cite web|url=http://www.informationweek.com/blog/main/archives/2008/08/antivirus_softw.html|title=Antivirus Software Heads for the Clouds|author=Erickson, Jon|work=Information Week|date=August 6, 2008|access-date=February 24, 2010|url-status=live|archive-url=https://web.archive.org/web/20110426191825/http://www.informationweek.com/blog/main/archives/2008/08/antivirus_softw.html|archive-date=April 26, 2011}}
Some examples of cloud anti-virus products are Panda Cloud Antivirus and Immunet. Comodo Group has also produced cloud-based anti-virus.{{cite web|url=http://wikipost.org/topic/2h7PggduooGeXanMKUGFghAIw1AqK6Xg/Comodo-Cloud-Antivirus-Beta3-Version-1-0-376043-87-is-Released.html|title=Comodo Cloud Antivirus released|publisher=wikipost.org|access-date=May 30, 2016|url-status=live|archive-url=https://web.archive.org/web/20160517014934/http://wikipost.org/topic/2h7PggduooGeXanMKUGFghAIw1AqK6Xg/Comodo-Cloud-Antivirus-Beta3-Version-1-0-376043-87-is-Released.html|archive-date=May 17, 2016}}{{cite web |url=https://help.comodo.com/uploads/helpers/Comodo_Cloud_Antivirus_ver.1.0_User_Guide.pdf |title=Comodo Cloud Antivirus User Guideline PDF |publisher=help.comodo.com |access-date=May 30, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160604133713/https://help.comodo.com/uploads/helpers/Comodo_Cloud_Antivirus_ver.1.0_User_Guide.pdf |archive-date=June 4, 2016}}
= Online scanning =
Some antivirus vendors maintain websites with free online scanning capability of the entire computer, critical areas only, local disks, folders or files. Periodic online scanning is a good idea for those that run antivirus applications on their computers because those applications are frequently slow to catch threats. One of the first things that malicious software does in an attack is disable any existing antivirus software and sometimes the only way to know of an attack is by turning to an online resource that is not installed on the infected computer.{{cite news|title=Online Anti-Virus Scans: A Free Second Opinion|author=Krebs, Brian |url=http://voices.washingtonpost.com/securityfix/2007/03/online_antivirus_scans_a_free.html|archive-url=https://web.archive.org/web/20110422182010/http://voices.washingtonpost.com/securityfix/2007/03/online_antivirus_scans_a_free.html|url-status=dead|archive-date=April 22, 2011|date=March 9, 2007|newspaper=The Washington Post|access-date=February 24, 2011}}
= Specialized tools =
Image:Rkhunter Ubuntu.png scanner is an engine to scan for Linux rootkits running on Ubuntu.]]
Virus removal tools are available to help remove stubborn infections or a certain type of infection. Examples include Windows Malicious Software Removal Tool,{{cite web|url=https://www.microsoft.com/en-us/download/details.aspx?id=9905|title=Windows Malicious Software Removal Tool 64-bit|access-date=December 27, 2022|work=Microsoft}} Kaspersky Virus Removal Tool,{{cite web|url=https://www.kaspersky.com/downloads/free-virus-removal-tool|title=Download Kaspersky Virus Removal Tool application|access-date=December 27, 2022|work=Kaspersky Lab}} and Sophos Scan & Clean.{{cite web|url=https://www.sophos.com/en-us/free-tools/virus-removal-tool|title=Sophos Scan & Clean|access-date=December 27, 2022|work=Sophos}} It is also worth noting that sometimes antivirus software can produce a false-positive result, indicating an infection where there is none.{{cite web|url=https://www.howtogeek.com/180162/how-to-tell-if-a-virus-is-actually-a-false-positive/|title=How To Tell If a Virus Is Actually a False Positive|access-date=October 2, 2018|work=How To Geek|date=January 20, 2014 }}
A rescue disk that is bootable, such as a CD or USB storage device, can be used to run antivirus software outside of the installed operating system in order to remove infections while they are dormant. A bootable rescue disk can be useful when, for example, the installed operating system is no longer bootable or has malware that is resisting all attempts to be removed by the installed antivirus software. Examples of software that can be used on a bootable rescue disk include the Kaspersky Rescue Disk,{{cite web|url=https://www.kaspersky.com/downloads/free-rescue-disk|title=Download Kaspersky Rescue Disk|access-date=December 27, 2022|work=Kaspersky Lab}} Trend Micro Rescue Disk,{{cite web|url=https://www.trendmicro.com/en_us/forHome/products/free-tools/rescue-disk.html|title=Rescue Disk|access-date=December 27, 2022|work=Trend Micro}} and Comodo Rescue Disk.{{cite web|url=https://www.comodo.com/business-security/network-protection/rescue-disk.php|title=Best Comodo Rescue Disk 2022|access-date=December 27, 2022|work=Comodo Group}}
Usage and risks
According to an FBI survey, major businesses lose $12 million annually dealing with virus incidents.{{cite web| title=FBI estimates major companies lose $12m annually from viruses| url=http://www.chattanoogan.com/articles/article_100752.asp| archive-url=https://archive.today/20120724063519/http://www.chattanoogan.com/articles/article_100752.asp| url-status=dead| archive-date=July 24, 2012| date=January 30, 2007| access-date=February 20, 2011}} A survey by Symantec in 2009 found that a third of small to medium-sized business did not use antivirus protection at that time, whereas more than 80% of home users had some kind of antivirus installed.{{cite web|url=http://www.staysafeonline.org/blog/small-and-medium-size-businesses-are-vulnerable |archive-url=https://archive.today/20120917203901/http://www.staysafeonline.org/blog/small-and-medium-size-businesses-are-vulnerable |url-status=dead |archive-date=September 17, 2012 |title=Small and Medium Size Businesses are Vulnerable |work=National Cyber Security Alliance |author=Kaiser, Michael |date=April 17, 2009 |access-date=February 24, 2011}} According to a sociological survey conducted by G Data Software in 2010 49% of women did not use any antivirus program at all.[https://www.spamfighter.com/News-15048-Nearly-50-Women-Dont-Use-Anti-virus-Software.htm Nearly 50% Women Don’t Use Anti-virus Software] {{webarchive|url=https://web.archive.org/web/20130513065750/http://www.spamfighter.com/News-15048-Nearly-50-Women-Dont-Use-Anti-virus-Software.htm |date=May 13, 2013}}. Spamfighter.com (September 2, 2010). Retrieved on January 3, 2017.
See also
- Anti-virus and anti-malware software
- CARO, the Computer Antivirus Research Organization
- Comparison of antivirus software
- Comparison of computer viruses
- EICAR, the European Institute for Computer Antivirus Research
- Endpoint detection and response
- Firewall software
- Internet security
- Linux malware
- Quarantine (antivirus program)
- Sandbox (computer security)
- Timeline of computer viruses and worms
- Virus hoax
Citations
{{reflist|30em}}
General bibliography
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- {{cite book|last = Szor|first = Peter|title = The Art of Computer Virus Research and Defense|publisher = Addison-Wesley|year = 2005|isbn = 978-0-321-30454-4}}
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{{Information security}}
{{malware}}
{{Antivirus software}}