計算機英文文獻(xiàn)和翻譯

1、鄭州大學(xué)畢業(yè)設(shè)計外文科技文獻(xiàn)翻譯題目：計算機病毒指導(dǎo)教師：李正民職稱：副教授學(xué)生姓名：張永星學(xué)號：20052430239專業(yè)：計算機科學(xué)與技術(shù)院（系）：信息工程學(xué)院完成時間：2009年5月25日2009年05月25日COMPUTERVIRUSESWhatarecomputerviruses?AccordingtoFredCohen?swell-knowndefinition,acomputervirusisacomputerprogramthatcaninfectothercomputerprogramsbymodifyingtheminsuchawayastoincludea(possibl

2、yevolved)copyofitself.Notethataprogramdoesnothavetoperformoutrightdamage(suchasdeletingorcorruptingfiles)inordertobecalleda“virusHowever,Cohenusesthetermswithinhisdefinition(e.g.“program”and“modify)abitdifferentlyfromthewaymostianiiresearchersusethem,andclassifiesasvirusessomethingswhichmostofuswoul

3、dnotconsiderviruses.Computervirusesarebitsofcodethatdamageoreraseinformation,files,orsoftwareprogramsinyourcomputer,muchlikevirusesthatinfecthumans,computervirusescanspread,andyourcomputercancatchaviruswhenyoudownloadaninfectedfilefromtheInternetorcopyaninfectedfilefromadiskette.Oncethevirusesisembe

4、ddedintoyourcomputer?sfiles,itcanimmediatelystarttodamageordestroyinformation,oritcanwaitforaparticulardateoreventtotriggeritsactivity.Whatarethemaintypesofviruses?Generally,therearetwomainclassesofviruses.ThefirstclassconsistsofthefileInfectorswhichattachthemselvestoordinaryprogramfiles.Theseusuall

5、yinfectarbitrary.COMand/or.EXEprograms,thoughsomecaninfectanyprogramforwhichexecutionisrequested,suchas.SYS,.OVL,.PR,8.MNUfiles.Fileinfectorscanbeeitherdirectactionorresident.Adirect-actionvirusselectsoneormoreotherprogramstoinfecteachothertimetheprogramwhichcontainsitisexecuted,andthereafterinfects

6、otherprogramswhen“they”areexecuted(asinthecaseoftheJerusalem)orwhencertainotherconditionsarefulf川ed.TheViennaisanexampleofadirect-actionvirus.Mostothervirusesareresident.Thesecondclassissystemorboot-recordinfectors:thoseviruses,whichinfectexecutablecode,foundincertainsystemareasonadiskthatarenotordi

7、naryfiles.OnDOSsystems,thereareordinaryboot-sectorviruses,whichinfectonlytheDOSbootsectorondiskettes.ExamplesincludeBrain,Stoned,Empire,Azusa,andMichelangelo.Suchvirusesarealwaysresidentviruses.Finally,afewvirusesareabletoinfectboth(theTequilavirusisoneexample).Thereareoftencalledmultipartite“viruse

8、s,thoughtherehasbeencriticismofthisname;anothernameis-artnb-fiilevirus.Filesystemorclusterviruses(e.g.Dir-II)arethosethatmodifydirectorytableentriessothatthevirusisloadedandexecutedbeforethedesiredprogramis.Notethattheprogramitselfisnotphysicallyaltered;onlythedirectoryentryis.Someconsidertheseinfec

9、torstobeathirdcategoryofviruses,whileothersconsiderthemtobeasub-categoryofthefileinfectors.Whataremacroviruses?Manyapplicationsprovidethefunctionalitytocreatemacros.Amacroisaseriesofcommandstoperformsomeapplication-specifictask.Macrosaredesignedtomakelifeeasier,forexample,toperformsomeeverydaytasksl

10、iketext-formattingorspreadsheetcalculations.Macroscanbesavedasaseriesofkeystrokes(theapplicationrecordwhatkeysyoupress);ortheycanbewritteninspecialmacrolanguages(usuallybasedonrealprogramminglanguageslikeCandBASIC).Modernapplicationscombinebothapproaches;andtheiradvancedmacrolanguagesareascomplexasg

11、eneralpurposeprogramminglanguages.Whenthemacrolanguageallowsfilestobemodified,itbecomespossibletocreatemacrosthatcopythemselvesfromonefiletoanother.Suchself-replicatingmacrosarecalledmacroviruses.MostmacrovirusesrununderWordforWindows.Sincethisisaverypopularwordprocessor,itprovidesaneffectivemeansfo

12、rvirusestospread.MostmacrovirusesarewrittenusingthemacrolanguageWordBasic.WordBasicisbasedonthegoodoldBASICprogramminglanguage.However,ithasmany(hundredsof)extensions(forexample,todealwithdocuments:edit,replacestring,obtainthenameofthecurrentdocument,opennewwindow,movecursor,etc.).WhatisaTrojanhorse

13、program?Atypeofprogramthatisoftenconfusedwithvirusesisa,Trojanhorse?program.Thisisnotavirus,butsimplyaprogram(oftenharmful)thatpretendstobesomethingelse.Forexample,youmightdownloadwhatyouthinkisanewgame;butwhenyourunit,itdeletesfilesonyourharddrive.Orthethirdtimeyoustartthegame,theprogramE-mailyours

14、avedpasswordstoanotherperson.Note:simplydownloadafiletoyourcomputerwon?tactivateavirusorTrojanhorse;youhavetoexecutethecodeinthefiletotriggerit.Thiscouldmeanrunningaprogramfile,oropeningaWord/Exceldocumentinaprogram(suchasWordorExcel)thatcanexecuteanymacrosinthedocument.Whatkindoffilescanspreadvirus

15、es?Viruseshavethepotentialtoinfectanytypeofexecutablecode,notjustthefilesthatarecommonlycalledprogramfilesForexample,somevirusesinfectexecutablecodeinthebootsectoroffloppydiskorinsystemareasofharddrives.Anothertypeofvirus,knownasa“macrovirus,caninfectwordprocessingandspreadsheetdocumentsthatusemacro

16、s.Andit?spossibleforHTMLdocumentscontainingJavaScriptorothertypesofexecutablecodetospreadvirusesorothermaliciouscode.Sincevirusescodemustbeexecutedtohaveanyeffect,filesthatthecomputertreatsaspuredataaresafe.Thisincludesgraphicsandsoundfilessuchas.gif,.jpg,.mp3,.wav,.etc.,aswellasplaintextin.txtfiles

17、.Forexample,justviewingpicturefileswon?tinfectyourcomputerwithavirus.Theviruscodehastobeinaform,suchasan.exeprogramfileoraWord.docfilewhichthecomputerwillactuallytrytoexecute.Howdovirusesspread?ThemethodologyofvirusinfectionwasprettystraightforwardwhenfirstcomputervirusessuchasLehighandJerusalemstar

18、tedappearing.Avirusisasmallpieceofcomputercode,usuallyformseveralbytestoafewtensofbytes,thatcando,well,somethingunexpected.Suchvirusesattachthemselvestoexecutablefilesprograms,sothattheinfectedprogram,beforeproceedingwithwhatevertasksitissupposedtodo,callstheviruscode.Oneofthesimplestwaystoaccomplis

19、hthatistoappendtheviruscodetotheendofthefile,andinsertacommandtothebeginningoftheprogramfilethatwouldjumprighttothebeginningoftheviruscode.Afterthevirusisfinished,itjumpsbacktothepointoforiginationintheprogram.Suchviruseswereverypopularinthelateeighties.Theearlieronesonlyknewhowtoattachthemselvesto.

20、Comfiles,sincestructureofa.COMfileismuchsimplerthanthatofan.EXEfileyetanotherexecutablefileformatinventedforMS-DOSoperatingsystem.ThefirstvirustobecloselystudiedwastheLehighvirus.Itattacheditselftothefilethatwasloadedbythesystematboottime-COMMAND.COM.thevirusdidalotofdamagetoitshost,soafterthree-fou

21、rreplicationsitwasnolongerusable.Forthatreason,thevirusnevermanagedtoescapetheuniversitynetwork.Whenyouexecuteprogramcodethat?sinfectedbyavirus,theviruscodewillalsorunandtrytoinfectotherprograms,eitheronthesamecomputeroronothercomputersconnectedtoitoveranetwork.Andthenewlyinfectedprogramswilltrytoin

22、fectyetmoreprograms.Whenyoushareacopyofaninfectedfilewithothercomputerusers,runningthefilemayalsoinfecttheircomputer;andfilesfromthosecomputersmayspreadtheinfectiontoyetmorecomputers.Ifyourcomputerifinfectedwithabootsectorvirus,thevirustriestowritecopiesofitselftothesystemareasoffloppydisksandharddi

23、sks.Thentheinfectedfloppydisksmayinfectothercomputersthatbootfromthem,andtheviruscopyontheharddiskwilltrytoinfectstillmorefloppies.Someviruses,knownas,multipartite?viruses,andspreadbothbyinfectingfilesandbyinfectingthebootareasoffloppydisks.Whatdovirusesdotocomputers?Virusesaresoftwareprograms,andth

24、eycandothesamethingsasanyotherprogramrunningonacomputer.Theaccrualeffectofanyparticularvirusdependsonhowitwasprogrammedbythepersonwhowrotethevirus.Somevirusesaredeliberatelydesignedtodamagefilesorotherwiseinterferewithyourcomputer?soperation,whileotherdon?tdoanythingbuttrytospreadthemselvesaround.Bu

25、teventheonesthatjustspreadthemselvesareharmful,sincetheydamagefilesandmaycauseotherproblemsintheprocessofspreading.Notethatvirusescan?tdoanydamagetohardware:theywon?tmeltdownyourCPU,burnoutyourharddrive,causeyourmonitortoexplode,etc.warningsaboutvirusesthatwillphysicallydestroyyourcomputerareusually

26、hoaxes,notlegitimateviruswarnings.ModernvirusescanexistonanysystemformMSDOSandWindow3.1toMacOS,UNIX,OS/2,WindowsNT.Someareharmless,thoughhardtocatch.TheycanplayajingleonChristmasorrebootyourcomputeroccasionally.Otheraremoredangerous.Theycandeleteorcorruptyourfiles,formatharddrives,ordosomethingoftha

27、tsort.Therearesomedeadlyonesthatcanspreadovernetworkswithorwithoutahost,transmitsensitiveinformationoverthenetworktoathirdparty,orevenmesswithfinancialdataon-line.What?sthestoryonviusesandE-mail?Youcan?tgetavirusjustbyreadingaplain-textE-mailmessageorUsenetpost.Whatyouhavetowatchoutforareencodedmess

28、agecontainingembeddedexecutablecode(i.e.,JavaScriptinHTMLmessage)ormessagethatincludeanexecutablefileattachment(i.e.,anencodedprogramfileoraWorddocumentcontainingmacros).InordertoactivateavirusorTrojanhorseprogram,youcomputerhastoexecutesometypeofcode.ThiscouldbeaprogramattachedtoanE-mail,aWorddocum

29、entyoudownloadedfromtheInternet,orsomethingreceivedonafloppydisk.There?snospecialhazardinfilesattachedtoUsenetpostsorE-mailmessages:they?renomoredangerousthananyotherfile.WhatcanIdotoreducethechanceofgettingvirusesfromE-mailTreatanyfileattachmentsthatmightcontainexecutablecodeascarefullyasyouwouldan

30、yothernewfiles:savetheattachmenttodiskandthencheckitwithanup-to-datevirusscannerbeforeopeningthefile.IfyouE-mailornewssoftwarehastheabilitytoautomaticallyexecuteJavaScript,Wordmacros,orotherexecutablecodecontainedinorattachedtoamessage,Istronglyrecommendthatyoudisablethisfeature.Mypersonalfeelingist

31、hatifanexecutablefileshowsupunexpectedlyattachedtoanE-mail,youshoulddeleteitunlessyoucanpositivelyverifywhatitis,Whoitcamefrom,andwhyitwassenttoyou.TherecentoutbreakoftheMelissaviruswasavividdemonstrationoftheneedtobeextremelycarefulwhenyoureceiveE-mailwithattachedfilesordocuments.JustbecauseanE-mai

32、lappearstocomefromsomeoneyoutrust,thisdoesNOTmeanthefileissafeorthatthesupposedsenderhadanythingtodowithit.SomeGeneralTipsonAvoidingVirusInfections1. Installanti-virussoftwarefromawell-known,reputablecompany.UPDATEitregularly,andUSEitregularly.Newvirusescomeouteverysingleday;ana-vprogramthathasn?tbe

33、enupdatedforseveralmonthswillnotprovidemuchprotectionagainstcurrentviruses.2. Inadditiontoscanningforvirusesonaregularbasis,installan,onaccess?scanner(includedinmostgooda-vsoftwarepackages)andconfigureittostartautomaticallyeachtimeyoubootyoursystem.Thiswillprotectyoursystembycheckingforviruseseachti

34、meyourcomputeraccessesanexecutablefile.3. Virusscansanynewprogramsorotherfilesthatmaycontainexecutablecodebeforeyourunoropenthem,nomatterwheretheycomefrom.TherehavebeencasesofcommerciallydistributedfloppydisksandCD-ROMsspreadingvirusinfections.4. Anti-virusprogramsaren?tverygoodatdetectingTrojanhors

35、eprograms,sobeextremelycarefulaboutopeningbinaryfilesandWord/Exceldocumentsfromunknownor,dubious?sources.Thisincludespostsinbinarynewsgroups,downloadsfromweb/ftpsitesthataren?twell-knownordon?thaveagoodreputation,andexecutablefilesunexpectedlyreceivedasattachmentstoE-mail.5. Beextremelycarefulabouta

36、cceptingprogramsorotherfliesduringon-linechatsessions:thisseemstobeoneofthemorecommonmeansthatpeoplewindupwithvirusorTrojanhorseproblems.Andifanyotherfamilymembers(especiallyyoungerones)usethecomputer,makesuretheyknownottoacceptanyfileswhileusingchat.6. Doregularbackups.SomevirusesandTrojanhorseprog

37、ramswilleraseorcorruptfilesonyourharddriveandarecentbackupmaybetheonlywaytorecoveryourdata.Ideally,youshouldbackupyourentiresystemonaregularbasis.Ifthisisn?tpractical,atleastbackupfilesyoucan?taffordtoloseorthatwouldbedifficulttoreplace:documents,bookmarkfiles,addressbooks,importantE-mail,etc.Dealin

38、gwithVirusInfectionsFirst,keepinmindNick?sFirstLawofComputerVirusComplaints“Justbecauseyourcomputerisactingstrangelyoroneofyourprogramsdoesn?tworkright,thisdoesnotmeanthatyourcomputerhasavirus.”1. Ifyouhaven?tusedagood,upto-dateanti-virusprogramonyourcomputer,dothatfirst.Manyproblemsblamedonvirusesa

39、reactuallycausedbysoftwareconfigurationerrorsorotherproblemsthathavenothingtodowithavirus.2. Ifyoudogetinfectedbyavirus,followthedirectioninyouranti-virusprogramforcleaningit.Ifyouhavebackupcopiesoftheinfectedfiles,usethosetorestorethefiles.Checkthefilesyourestoretomakesureyourbackupsweren?tinfected

40、.3. forassistance,checkthewebsiteandsupportserviceforyouranti-virussoftware.Note:ingeneral,drasticmeasuressuchasformattingyourharddriveorusingFDISKshouldbeavoided.Theyarefrequentlyuselessatcleaningavirusinfection,andmaydomoreharmthangoodunlessyou?reveryknowledgeableabouttheeffectsoftheparticularviru

41、syou?redealingwith.計算機病毒什么是計算機病毒？按照FredCohen的廣為流傳的定義，計算機病毒是一種侵入其他計算機程序中的計算機程序，他通過修改其他的程序從而將（也可能是自身的變形）的復(fù)制品嵌入其中。注意一個程序之所以成為“病毒”，并非一定要起徹底的破壞作用（如刪除或毀壞文件）。然而，Cohen在他的定義（即“程序”和“修改”）中使用的“病毒”這個術(shù)語與大多數(shù)反病毒研究人員使用的“病毒”術(shù)語有些差別，他把一些我們多數(shù)人認(rèn)為不是病毒的東西也歸類為病毒。計算機病毒是一些能破壞或刪除計算機中的信息、文件或程序的代碼。正如感染人體的病毒一樣，計算機病毒能夠擴散。當(dāng)你的計算機從互聯(lián)

42、網(wǎng)上下載一個被感染的文件，或者從磁盤上復(fù)制一個被感染的文件時，你的計算機就會染上病毒。而一旦病毒進入到你的計算機文件中，它就能馬上破壞或摧毀其中的信息，或者等到某個特殊的日期或事件來臨時才觸發(fā)其破壞活動。個人計算機病毒主要有哪些類型？一般來說，主要存在著兩類計算機病毒。第一類由文件感染型病毒組成，他們將自身依附在普通的程序文件上。這些病毒通常感染任意的.COM?口/或EXEi件，盡管有些也感染具有執(zhí)行功能的文件，如.SYS,.OVL,.PRG和.MNUt件.文件感染型病毒又可分為“立即執(zhí)行型”和“駐留型”。立即執(zhí)行型病毒在含有它的程序每次執(zhí)行是都對其他的一個或多個文件進行感染，而駐留型病毒在被

43、感染的程序第一次執(zhí)行時先將自己隱藏在內(nèi)存中的某個地方，以后當(dāng)其他程序執(zhí)行或當(dāng)某些其他程序特定條件滿足時就對它們進行感染（就像耶路撒冷病毒一樣）。維也納病毒是立即執(zhí)行型病毒的一個例子，大多數(shù)其他病毒則是駐留型病與。第二類病毒是系統(tǒng)病毒或引導(dǎo)區(qū)記錄感染型病毒，這些感染可執(zhí)行代碼的病毒出現(xiàn)在磁盤的某些系統(tǒng)區(qū)中，而不是普通文件中。在DOSS統(tǒng)中，常見的引導(dǎo)扇區(qū)病毒和主引導(dǎo)記錄病毒，前者只感染DOaI導(dǎo)扇區(qū)，后者感染硬盤的主引導(dǎo)記錄和軟盤的DOS8I導(dǎo)扇區(qū)。第二類病毒的例子包括大腦病毒、大麻病毒、帝國病毒、Azusa以及米開郎基羅病毒等，此類病毒通常為駐留型病毒。另外，有些病毒能感染上述兩種對象（如蒸儲

44、酒病毒就是一個例子），這些病毒常稱為“多成分”病毒（盡管這個名字曾遭到過批評），它們的另一個名字是“引導(dǎo)區(qū)和文件型”病毒。文件系統(tǒng)型病毒或“簇”病毒（如Dir-II病毒）是那種修改文件目錄表項并且在文件裝入、執(zhí)行前就被裝入和執(zhí)行的病毒。注意，程序本身實際上并沒有被修改，只是目錄項被修改。有些人把這種感染型病毒看作是第三類病毒，而另一些人把它看作是文件感染型病毒的子類。什么是宏病毒？許多應(yīng)用程序都提供了創(chuàng)建宏的功能。宏是一個完成特定應(yīng)用任務(wù)的命令序列。設(shè)計宏的目的是使諸如文本格式化或電子表格計算這樣的日常工作更為簡單。宏可以保存成一系列擊鍵（即應(yīng)用程序記錄你按了哪些鍵），或者它們能夠用某些特殊的

45、宏語言像通用程序設(shè)計語言一樣復(fù)雜。當(dāng)宏語言允許文件被修改時，就有可能建立能將自身從一個文件復(fù)制到另一個文件上的宏。這種具有自復(fù)制功能的宏稱作宏病毒。大多數(shù)的宏病毒都是在Windows的Word軟件中運行的，因為Word是一種流行的字處理器，它為病毒的擴散提供了有效的途徑。大部分的宏病毒是用WordBasic宏語言編寫的。WordBasic基于以前的性能良好的BASIC編程語言，然而它有很多（幾百種）擴展功能（如下列文件處理功能：編輯、替換字符串、獲取當(dāng)前文檔的名字、打開一個新的窗口、移動光標(biāo)等）。什么是特洛伊木馬程序?通常與病毒想混淆的一種程序是特洛伊木馬程序,0它不是病毒，僅僅是扮作其他東西

46、的程序（常常是有害的）。例如，你可能下載了你認(rèn)為是新游戲的東西，但當(dāng)你運行它時，它刪除了你硬盤上的文件?；蛘弋?dāng)你第三次運行該游戲時，該程序把你保存了的密碼發(fā)送給其他人。注意：僅僅把一個文件下載到你計算機不會激活病毒或特洛伊木馬程序。你必須執(zhí)行文件中的代碼才能出觸發(fā)它。這意味著運行一個程序文件或打開一個可以執(zhí)行文檔中的宏的程序（如Word或Excel）中的Word/Excel文檔。哪些文件可以傳播計算機病毒？計算機病毒有感染任何可執(zhí)行代碼的潛力，不僅僅是通常叫做“程序文件”的文件。例如，某些計算機病毒感染軟盤引導(dǎo)區(qū)或硬盤系統(tǒng)區(qū)域的可執(zhí)行代碼。另外有一種叫做“宏”的計算機病毒，可以感染使用宏的字處

47、理程序和電子表格程序。包括JavaScript和其他可執(zhí)行類型代碼的HTMLC檔也可能傳播計算機病毒或其他惡意代碼。因為計算機病毒代碼必須被執(zhí)行才能實現(xiàn)任何感染，所以被計算機當(dāng)作純數(shù)據(jù)的文件是安全的。這包括.gif、.jpg、.mp3、.wav等圖形和聲音文件，也包括以.txt為擴展名的簡單文本文件。例如，只查看圖片不會使計算機感染病毒。病毒代碼必須存在于一個形式中，像計算機實際上可執(zhí)行的.exe程序文件或Word和.doc文件。計算機病毒是如何傳播的？當(dāng)初的病毒（如LehighandJerusalem病毒）開始出現(xiàn)的時候，病毒感染的的方法是非常直截了當(dāng)?shù)?。一個病毒是一小段計算機代碼，通常是幾

48、個到幾十個字節(jié)，它們能做一些意想不到的事情。比如，這些病毒將自身依附到可執(zhí)行文件（即程序）上面，這樣，被感染的程序在執(zhí)行它自身的任務(wù)前首先調(diào)用病毒代碼。實現(xiàn)這種目的的一個最簡單的方法是將病毒代碼附加文件的尾部，并且在程序文件的開頭處插入一條命令，使得控制正好能跳到病毒代碼的開始處，在病毒代碼被執(zhí)行完以后，控制又跳回到程序的初始點。這種病毒在80年代后期很常見。早期的病毒只知道附加到.COM文件上，因為他的結(jié)構(gòu)比MS-DOSM乍系統(tǒng)的另一種可執(zhí)行文件格式一一.EXE文件更簡單。第一個被人們深入研究的病毒是Lehigh病毒，它把自身附加到啟動時由系統(tǒng)裝入的文件COMMAND.COM病毒對宿主程序能

49、帶來很多破壞，因為這些程序在經(jīng)過三、四次復(fù)制以后就不可再使用。正因如此，病毒無法從大學(xué)的網(wǎng)絡(luò)上消除干凈。當(dāng)你執(zhí)行一個感染了病毒的程序代碼時，病毒程序也將進行并試圖感染本計算機過通過網(wǎng)絡(luò)相連的其他計算機上的其他程序。最新感染的程序?qū)⒃噲D感染更多的程序。當(dāng)你與其他計算機用戶共享一個感染文件的拷貝時，運行該文件也可以感染他們的計算機。并且，這些計算機中的文件也可能把病毒傳染給更多的計算機。如果你的餓計算機已經(jīng)感染了引導(dǎo)區(qū)病毒，該病毒試圖把自身的拷貝寫到軟盤的系統(tǒng)區(qū)域。然后，感染了的軟盤可能感染用它們引導(dǎo)的其他計算機，而硬盤上的病毒拷貝將試圖感染更多的軟盤。一些病毒，也叫做“多部分”病毒，既可以通過感染可以通過感染軟盤的引導(dǎo)扇區(qū)來傳播。計算機病毒對計算機做什么？病毒是軟件程序，它所做的事情與計算機上運行的任何其他程序所做的事情相同。任何一個特別病毒的實際效果取決于編寫病毒的程序員是如何編寫的。有些病毒有意設(shè)計為損壞文件和妨礙計算機的運行，也有一些病毒只傳播自己而不做其他任何事情。但即使只傳播自己的病毒也是有害的，因為它們在傳播過程中損壞文件，還可能引起其他問題。注意病毒不會對硬件造成任何損壞：它們不會徹底損壞你的CPU也不會燒壞你的硬盤，引起你的顯示器爆炸等。關(guān)于