缓冲区溢出实验说明

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1、IntroductionThisassignmenthelpsyoudevelopadetailedunderstandingofthecallingstackorganizationonanIA32processor.Itinvolvesapplyingaseriesofbufferoverflowattacksonanexecutablefilebufbombinthelabdirectory.Note:Inthislab,youwillgainfirsthandexperiencewith

2、oneofthemethodscommonlyusedtoexploitsecurityweaknessesinoperatingsystemsandnetworkservers.Ourpurposeistohelpyoulearnabouttheruntimeoperationofprogramsandtounderstandthenatureofthisformofsecurityweaknesssothatyoucanavoiditwhenyouwritesystemcode.Wedono

3、tcondonetheuseoftheseoranyotherformofattacktogainunauthorizedaccesstoanysystemresources.Therearecriminalstatutesgoverningsuchactivities.LogintheServerEveryonehasanaccountonourServer,theaddressis10.13.75.177,andusernameisstu+yourstudentnumber(ex:stu04

4、72001),thedefaultpasswordiscsapp2007.Youcangettheaccesswithputty.Startbycopyingbuflab-handout.tartoa(protected)directoryinwhichyouplantodoyourwork.Thengivethecommand“tarxvfbuflab-handout.tar”.Thiswillcauseanumberoffilestobeunpackedinthedirectory:MAKE

5、COOKIE:Generatesa“cookie”basedonyourname.BUFBOMB:Thecodeyouwillattack.SENDSTRING:Autilitytohelpconvertbetweenstringformats.AlloftheseprogramsarecompiledtorunonLinuxmachines.Inthefollowinginstructions,wewillassumethatyouhavecopiedthethreeprogramstoapr

6、otectedlocaldirectory,and9thatyouareexecutingtheminthatlocaldirectory.GetyourcookieAcookieisastringofeighthexadecimaldigitsthatis(withhighprobability)uniquetoyourname.Youcangenerateyourcookiewiththemakecookieprogramgivingyournameastheargument.Forexam

7、ple:unix>./makecookiebovik0x78327b66TheBUFBOMBProgramTheBUFBOMBprogramreadsastringfromstandardinputwithafunctiongetbufhavingthefollowingCcode:1intgetbuf()2{3charbuf[12];4Gets(buf);5return1;6}ThefunctionGetsissimilartothestandardlibraryfunctiongets—it

8、readsastringfromstandardinput(terminatedby‘’orend-of-file)andstoresit(alongwithanullterminator)atthespecifieddestination.Inthiscode,thedestinationisanarraybufhavingsufficientspacefor12characters.NeitherGetsnorgetshasanywaytodeterminewhetherthereise