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'{{other uses|Trojan horse (disambiguation)}} A '''Trojan horse''', or '''Trojan''', in [[computing]] is any [[malware|malicious]] [[computer program]] which misrepresents itself as useful, routine, or interesting in order to persuade a victim to install it. The term is derived from the [[Ancient Greek]] story of the [[Trojan Horse|wooden horse]].<ref>{{Cite conference | publisher = DTIC Document | last = Landwehr | first = C. E |author2=A. R Bull |author3=J. P McDermott |author4=W. S Choi | title = A taxonomy of computer program security flaws, with examples | url = http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA465587 | year = 1993 | accessdate = 2012-04-05 }}</ref><ref>{{Cite web | title = Trojan Horse Definition | accessdate = 2012-04-05 | url = http://www.techterms.com/definition/trojanhorse }}</ref><ref>{{Cite news | title = Trojan horse | work = Webopedia | accessdate = 2012-04-05 | url = http://www.webopedia.com/TERM/T/Trojan_horse.html }}</ref><ref>{{Cite web | title = What is Trojan horse? - Definition from Whatis.com | accessdate = 2012-04-05 | url = http://searchsecurity.techtarget.com/definition/Trojan-horse }}</ref><ref>{{Cite web | title = Trojan Horse: [coined By MIT-hacker-turned-NSA-spook Dan Edwards] N. | accessdate = 2012-04-05 | url = http://www.anvari.org/fortune/Miscellaneous_Collections/291162_trojan-horse-coined-by-mit-hacker-turned-nsa-spook-dan-edwards-n.html }}</ref> Trojans are generally spread by some form of [[Social engineering (security)|social engineering]], for example where a user is duped into executing an e-mail attachment disguised to be unsuspicious, (e.g., a routine form to be filled in), or by [[drive-by download]]. Although their payload can be anything, many moderns forms act as a [[Backdoor (computing)|backdoor]], contacting a controller which can then have unauthorized access to the affected computer.<ref>{{cite web|title=What is the difference between viruses, worms, and Trojans?|url=http://www.symantec.com/business/support/index?page=content&id=TECH98539|publisher=Symantec Corporation|accessdate=2009-01-10}}</ref> While Trojans and backdoors are not easily detectable by themselves, computers may appear to run slower due to heavy processor or network usage. Trojans generally do not attempt to inject themselves into other files (like a [[computer virus]]) or otherwise propagate themselves ([[Computer worm|worm]]).<ref>{{ Cite web | title = VIRUS-L/comp.virus Frequently Asked Questions (FAQ) v2.00 (Question B3: What is a Trojan Horse?) | date = 9 October 1995 | accessdate = 2012-09-13 | url = http://www.faqs.org/faqs/computer-virus/faq/ }}</ref> ==Purpose and uses== If run with [[superuser|elevated privileges]] or installed a Trojan will generally have unlimited access. What it does with this power depends on the motives of the attacker. ===Destructive=== * [[Crash (computing)|Crashing the computer]] * Modification or [[File deletion|deletion of files]] * Data corruption * [[Format (computing)|Formatting]] disks, destroying all contents * Spread malware across the network ===Use of resources or identity=== * Use of the machine as part of a [[botnet]] (e.g. to perform automated [[Spam (electronic)|spamming]] or to [[Denial-of-service attack#Distributed attack|distribute Denial-of-service attacks]]) * Using computer resources for mining [[cryptocurrency|cryptocurrencies]] <ref name="CryptoMining">Robert McMillan (2013): [http://www.wired.com/2013/04/bitcoin-trojan/ Trojan Turns Your PC Into Bitcoin Mining Slave], Retrieved on 2015-02-01</ref> * Using the infected computer as proxy for illegal activities and/or attacks on other computers. == Heading text == ===Money theft=== * [[Electronic money]] theft * Hack Internet Banking Information (username & Password) * Encrypting files; a ransom payment may be demanded for decryption, as with the [[CryptoLocker]] ransomware ===Data theft=== * [[Data theft]], including for [[industrial espionage]] * Information with financial implications such as passwords and [[payment card]] information ===Spying, surveilance or stalking=== * [[Keystroke logging]] * [[Data scraping#Screen scraping|Watching the user's screen]] * Viewing the user's [[webcam]] * [[Remote administration|Controlling the computer system remotely]] Trojan horses in this way may require interaction with a malicious controller (not necessarily distributing the Trojan horse) to fulfill their purpose. It is possible for those involved with Trojans to scan computers on a network to locate any with a Trojan horse installed, which the hacker can then control.<ref name="Crapanzano">Jamie Crapanzano (2003): [http://www.sans.org/reading_room/whitepapers/malicious/deconstructing_subseven_the_trojan_horse_of_choice_953 "Deconstructing SubSeven, the Trojan Horse of Choice", SANS Institute], Retrieved on 2009-06-11</ref> Some Trojans take advantage of a security flaw in older versions of Internet Explorer and Google Chrome to use the host computer as an [[anonymizer|anonymizer proxy]] to effectively hide Internet usage,<ref name=AAA>{{cite news |url=http://www.spywareloop.com/news/trojan-horse|title=Trojan Horse in SpyWareLoop.com|author= Vincentas |newspaper=''Spyware Loop'' |date=11 July 2013 |accessdate=28 July 2013}}</ref> enabling the controller to use the Internet for illegal purposes while all potentially incriminating evidence indicates the infected computer or its IP address. The host's computer may or may not show the internet history of the sites viewed using the computer as a proxy. The first generation of anonymizer Trojan horses tended to leave their tracks in the page view histories of the host computer. Later generations of the Trojan horse tend to "cover" their tracks more efficiently. Several versions of [[Sub7]] have been widely circulated in the US and Europe and became the most widely distributed examples of this type of Trojan horse.<ref name="Crapanzano" /> In German-speaking countries, [[spyware]] used or made by the government is sometimes called ''govware''. Govware is typically a trojan horse software used to intercept communications from the target computer. Some countries like Switzerland and Germany have a legal framework governing the use of such software.<ref name="cupa">Basil Cupa, [http://www.zora.uzh.ch/81157/1/Cupa_Living_in_Surveillance_Societies_2012.pdf Trojan Horse Resurrected: On the Legality of the Use of Government Spyware (Govware)], LISS 2013, pp. 419-428</ref><ref>http://www.ejpd.admin.ch/content/ejpd/de/home/themen/sicherheit/ueberwachung_des_post-/faq_vuepf.faq_3.html</ref> Examples of govware trojans include the Swiss [[MiniPanzer and MegaPanzer]]<ref name="tech">{{cite web|url=http://news.techworld.com/security/3200593/swiss-coder-publicises-government-spy-trojan/ |title=Swiss coder publicises government spy Trojan - Techworld.com |publisher=News.techworld.com |accessdate=2014-01-26}}</ref> and the [[Chaos_Computer_Club#Staatstrojaner|German "state trojan" nicknamed R2D2]].<ref name="cupa"/> Due to the popularity of botnets among hackers and the availability of advertising services that permit authors to violate their users' privacy, Trojan horses are becoming more common. According to a survey conducted by [[BitDefender]] from January to June 2009, "Trojan-type malware is on the rise, accounting for 83-percent of the global malware detected in the world." Trojans have a relationship with worms, as they spread with the help given by worms and travel across the internet with them.<ref>[http://news.bitdefender.com/NW1094-en--BitDefender-Malware-and-Spam-Survey-finds-E-Threats-Adapting-to-Online-Behavioral-Trends.html BitDefender.com] Malware and Spam Survey''</ref> The anti-virus company BitDefender has stated that approximately 15% of computers are members of a botnet, usually recruited by a Trojan infection.<ref>{{cite web|last=Datta|first=Ganesh|title=What are Trojans?|url=http://securaid.com/windows/2014/08/what-are-trojans/|work=SecurAid}}</ref> ==Notable Trojan horses == * [[Netbus]] Advance System Care(by Carl-Fredrik Neikter) * Subseven or [[Sub7]](by Mobman) * [[Back Orifice]] (Sir Dystic) * [[Beast (Trojan horse)|Beast]] * [[Zeus (Trojan horse)|Zeus]] * Flashback Trojan ([[Trojan BackDoor.Flashback]]) * [[ZeroAccess botnet|ZeroAccess]] * [[Koobface]] * [[Vundo]] ==See also== {{Columns-list|2| * [[Computer security]] * [[Remote administration]] * [[Remote administration software]] * [[Cyber spying]] * [[Dancing pigs]] * [[Exploit (computer security)]] * [[Industrial espionage]] * [[Malware]] * [[Principle of least privilege]] * [[Privacy-invasive software]] * [[Reverse connection]] * [[Rogue security software]] * [[Social engineering (security)]] * [[Spam (electronic)|Spam]] * [[Spyware]] * [[Timeline of computer viruses and worms]] }} ==References== * Carnegie Mellon University (1999): [http://www.cert.org/advisories/CA-1999-02.html "CERT Advisory CA-1999-02 Trojan Horses"], Retrieved on 2009-06-10. {{reflist|2}} ==External links== * {{dmoz|Computers/Security/Malicious_Software/Trojan_Horses|Trojan Horses}} {{Malware}} {{Portal bar|Computer security|Software}} {{Authority control}} {{DEFAULTSORT:Trojan Horse (Computing)}} [[Category:Trojan horses| ]] [[Category:Social engineering (computer security)]] [[Category:Spyware]] [[Category:Web security exploits]]'