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1、哈尔滨工业大学（威海）学士学位论文英文参考文献及翻译[原文]COMPUTERVIRUSESWhatarecomputerviruses?AccordingtoFredCohen’swell-knowndefinition,acomputervirusisacomputerprogramthatcaninfectothercomputerprogramsbymodifyingtheminsuchawayastoincludea(possiblyevolved)copyofitself.Notethataprogramdoesnothaveto
2、performoutrightdamage(suchasdeletingorcorruptingfiles)inordertobecalleda“virus”.However,Cohenusesthetermswithinhisdefinition(e.g.“program”and“modify”)abitdifferentlyfromthewaymostanti-virusresearchersusethem,andclassifiesasvirusessomethingswhichmostofuswouldnotconsiderviru
3、ses.Computervirusesarebitsofcodethatdamageoreraseinformation,files,orsoftwareprogramsinyourcomputer,muchlikevirusesthatinfecthumans,computervirusescanspread,andyourcomputercancatchaviruswhenyoudownloadaninfectedfilefromtheInternetorcopyaninfectedfilefromadiskette.Oncethevi
4、rusesisembeddedintoyourcomputer’sfiles,itcanimmediatelystarttodamageordestroyinformation,oritcanwaitforaparticulardateoreventtotriggeritsactivity.Whatarethemaintypesofviruses?Generally,therearetwomainclassesofviruses.ThefirstclassconsistsofthefileInfectorswhichattachthemse
5、lvestoordinaryprogramfiles.Theseusuallyinfectarbitrary.COMand/or.EXEprograms,thoughsomecaninfectanyprogramforwhichexecutionisrequested,suchas.SYS,.OVL,.PRG,&.MNUfiles.Fileinfectorscanbeeitherdirectactionorresident.Adirect-actionvirusselectsoneormoreotherprogramstoinfecteac
6、hothertimetheprogramwhichcontainsitisexecuted,andthereafterinfectsotherprogramswhen“they”areexecuted(asinthecaseoftheJerusalem)orwhencertainotherconditionsarefulfilled.TheViennaisanexampleofadirect-actionvirus.Mostothervirusesareresident.Thesecondclassissystemorboot-record
7、infectors:thoseviruses,whichinfectexecutablecode,foundincertainsystemareasonadiskthatarenotordinaryfiles.OnDOSsystems,thereareordinaryboot-sectorviruses,whichinfectonlytheDOSbootsectorondiskettes.ExamplesincludeBrain,Stoned,Empire,Azusa,andMichelangelo.Suchvirusesarealways
8、residentviruses.Finally,afewvirusesareabletoinfectboth(theTequilavirusisoneexample).There
