tasksubuntu12.04
ubuntu12.04 时间:2021-03-29 阅读:()
SEEDLabs–HeartbleedAttack1HeartbleedAttackLabCopyrightc2016WenliangDu,SyracuseUniversity.
ThedevelopmentofthisdocumentwaspartiallyfundedbytheNationalScienceFoundationunderAwardNo.
1303306and1318814.
ThisworkislicensedunderaCreativeCommonsAttribution-NonCommercial-ShareAlike4.
0InternationalLicense.
Ahuman-readablesummaryof(andnotasubstitutefor)thelicenseisthefollowing:Youarefreetocopyandredistributethematerialinanymediumorformat.
Youmustgiveappropriatecredit.
Ifyouremix,transform,orbuilduponthematerial,youmustdistributeyourcontributionsunderthesamelicenseastheoriginal.
Youmaynotusethematerialforcommercialpurposes.
1OverviewTheHeartbleedbug(CVE-2014-0160)isasevereimplementationawintheOpenSSLlibrary,whichen-ablesattackerstostealdatafromthememoryofthevictimserver.
Thecontentsofthestolendatadependonwhatisthereinthememoryoftheserver.
Itcouldpotentiallycontainprivatekeys,TLSsessionkeys,usernames,passwords,creditcards,etc.
ThevulnerabilityisintheimplementationoftheHeartbeatprotocol,whichisusedbySSL/TLStokeeptheconnectionalive.
Theobjectiveofthislabisforstudentstounderstandhowseriousthisvulnerabilityis,howtheattackworks,andhowtoxtheproblem.
TheaffectedOpenSSLversionrangeisfrom1.
0.
1to1.
0.
1f.
TheversioninourUbuntuVMis1.
0.
1.
2LabEnvironmentInthislab,weneedtosetuptwoVMs:onecalledattackermachineandtheothercalledvictimserver.
Weusethepre-builtSEEDUbuntu12.
04VM.
TheVMsneedtousetheNAT-Networkadapterforthenetworksetting.
ThiscanbedonebygoingtotheVMsettings,pickingNetwork,andclickingtheAdaptortagtoswitchtheadaptertoNAT-Network.
MakesurebothVMsareonthesameNAT-Network.
ThewebsiteusedinthisattackcanbeanyHTTPSwebsitethatusesSSL/TLS.
However,sinceitisillegaltoattackarealwebsite,wehavesetupawebsiteinourVM,andconducttheattackonourownVM.
Weuseanopen-sourcesocialnetworkapplicationcalledELGG,andhostitinthefollowingURL:https://www.
heartbleedlabelgg.
com.
Weneedtomodifythe/etc/hostsleontheattackermachinetomaptheservernametotheIPad-dressoftheserverVM.
Searchthefollowinglinein/etc/hosts,andreplacetheIPaddress127.
0.
0.
1withtheactualIPaddressoftheserverVMthathoststheELGGapplication.
127.
0.
0.
1www.
heartbleedlabelgg.
com3LabTasksBeforeworkingonthelabtasks,youneedtounderstandhowtheheartbeatprotocolworks.
Theheartbeatprotocolconsistsoftwomessagetypes:HeartbeatRequestpacketandHeartbeatResponsepacket.
ClientsendsaHeartbeatRequestpackettotheserver.
Whentheserverreceivesit,itsendsbackacopyofthereceivedmessageintheHeartbeatResponsepacket.
Thegoalistokeeptheconnectionalive.
TheprotocolisillustratedinFigure1.
SEEDLabs–HeartbleedAttack2Figure1:OverviewoftheHeartbeatProtocol3.
1Task1:LaunchtheHeartbleedAttack.
Inthistask,studentswilllaunchtheHeartbleedattackonoursocialnetworksiteandseewhatkindofdamagescanbeachieved.
TheactualdamageoftheHeartbleedattackdependsonwhatkindofinformationisstoredintheservermemory.
Iftherehasnotbeenmuchactivityontheserver,youwillnotbeabletostealusefuldata.
Therefore,weneedtointeractwiththewebserveraslegitimateusers.
LetusdoitastheSEEDLabs–HeartbleedAttack3administrator,anddothefollowings:Visithttps://www.
heartbleedlabelgg.
comfromyourbrowser.
Loginasthesiteadministrator.
(UserName:admin;Password:seedelgg)AddBobyasfriend.
(GotoMore->MembersandclickBoby->AddFriend)SendBobyaprivatemessage.
Afteryouhavedoneenoughinteractionaslegitimateusers,youcanlaunchtheattackandseewhatinformationyoucangetoutofthevictimserver.
WritingtheprogramtolaunchtheHeartbleedattackfromscratchisnoteasy,becauseitrequiresthelow-levelknowledgeoftheHeartbeatprotocol.
Fortunately,otherpeoplehavealreadywrittentheattackcode.
Therefore,wewillusetheexistingcodetogainrst-handexperienceintheHeartbleedattack.
Thecodethatweuseiscalledattack.
py,whichwasoriginallywrittenbyJaredStafford.
Wemadesomesmallchangestothecodeforeducationalpurposes.
Youcandownloadthecodefromthelab'swebsite,changeitspermissionsotheleisexecutable.
Youcanthenruntheattackcodeasfollows:$.
/attack.
pywww.
heartbleedlabelgg.
comYoumayneedtoruntheattackcodemultipletimestogetusefuldata.
Tryandseewhetheryoucangetthefollowinginformationfromthetargetserver.
Usernameandpassword.
User'sactivity(whattheuserhasdone).
Theexactcontentoftheprivatemessage.
ForeachpieceofsecretthatyoustealfromtheHeartbleedattack,youneedtoshowthescreen-dumpastheproofandexplainhowyoudidtheattack,andwhatyourobservationsare.
3.
2Task2:FindtheCauseoftheHeartbleedVulnerabilityInthistask,studentswillcomparetheoutcomeofthebenignpacketandthemaliciouspacketsentbytheattackercodetondoutthefundamentalcauseoftheHeartbleedvulnerability.
TheHeartbleedattackisbasedontheHeartbeatrequest.
Thisrequestjustsendssomedatatotheserver,andtheserverwillcopythedatatoitsresponsepacket,soallthedataareechoedback.
Inthenormalcase,supposethattherequestincludes3bytesofdata"ABC",sothelengtheldhasavalue3.
Theserverwillplacethedatainthememory,andcopy3bytesfromthebeginningofthedatatoitsresponsepacket.
Intheattackscenario,therequestmaycontain3bytesofdata,butthelengtheldmaysay1003.
Whentheserverconstructsitsresponsepacket,itcopiesfromthestartingofthedata(i.
e.
"ABC"),butitcopies1003bytes,insteadof3bytes.
Theseextra1000typesobviouslydonotcomefromtherequestpacket;theycomefromtheserver'sprivatememory,andtheymaycontainotheruser'sinformation,secretkeys,password,etc.
Inthistask,wewillplaywiththelengtheldoftherequest.
First,let'sunderstandhowtheHeartbeatresponsepacketisbuiltfromFigure2.
WhentheHeartbeatrequestpacketcomes,theserverwillparsethepackettogetthepayloadandthePayloadlengthvalue(whichishighlightedinFigure2).
Here,thepayloadisonlya3-bytestring"ABC"andthePayloadlengthvalueisexactly3.
Theserverprogramwillblindlytakethislengthvaluefromtherequestpacket.
ItthenbuildstheresponsepacketbypointingtoSEEDLabs–HeartbleedAttack4Figure2:TheBenignHeartbeatCommunicationFigure3:TheHeartbleedAttackCommunicationthememorystoring"ABC"andcopyPayloadlengthbytestotheresponsepayload.
Inthisway,theresponsepacketwouldcontaina3-bytestring"ABC".
WecanlaunchtheHeartBleedattacklikewhatisshowninFigure3.
Wekeepthesamepayload(3bytes),butsetthePayloadlengtheldto1003.
TheserverwillagainblindlytakethisPayloadlengthvaluewhenbuildingtheresponsepacket.
Thistime,theserverprogramwillpointtothestring"ABC"andcopy1003bytesfromthememorytotheresponsepacketasapayload.
Besidesthestring"ABC",theextra1000bytesarecopiedintotheresponsepacket,whichcouldbeanythingfromthememory,suchassecretactivity,logginginformation,passwordandsoon.
OurattackcodeallowsyoutoplaywithdifferentPayloadlengthvalues.
Bydefault,thevalueissettoaquitelargeone(0x4000),butyoucanreducethesizeusingthecommandoption"-l"(letterell)SEEDLabs–HeartbleedAttack5or"--length"asshowninthefollowingexamples:$.
/attack.
pywww.
heartbleedlabelgg.
com-l0x015B$.
/attack.
pywww.
heartbleedlabelgg.
com--length83Yourtaskistoplaywiththeattackprogramwithdifferentpayloadlengthvaluesandanswerthefollow-ingquestions:Question2.
1:Asthelengthvariabledecreases,whatkindofdifferencecanyouobserveQuestion2.
2:Asthelengthvariabledecreases,thereisaboundaryvaluefortheinputlengthvari-able.
Atorbelowthatboundary,theHeartbeatquerywillreceivearesponsepacketwithoutattachinganyextradata(whichmeanstherequestisbenign).
Pleasendthatboundarylength.
Youmayneedtotrymanydifferentlengthvaluesuntilthewebserversendsbackthereplywithoutextradata.
Tohelpyouwiththis,whenthenumberofreturnedbytesissmallerthantheexpectedlength,thepro-gramwillprint"ServerprocessedmalformedHeartbeat,butdidnotreturnanyextradata.
"3.
3Task3:CountermeasureandBugFixToxtheHeartbleedvulnerability,thebestwayistoupdatetheOpenSSLlibrarytothenewestversion.
Thiscanbeachievedusingthefollowingcommands.
Itshouldbenotedthatonceitisupdated,itishardtogobacktothevulnerableversion.
Therefore,makesureyouhavenishedtheprevioustasksbeforedoingtheupdate.
YoucanalsotakeasnapshotofyourVMbeforetheupdate.
#sudoapt-getupdate#sudoapt-getupgradeTask3.
1TryyourattackagainafteryouhaveupdatedtheOpenSSLlibrary.
Pleasedescribeyourobser-vations.
Task3.
2TheobjectiveofthistaskistogureouthowtoxtheHeartbleedbuginthesourcecode.
ThefollowingC-stylestructure(notexactlythesameasthesourcecode)istheformatoftheHeartbeatrequest/responsepacket.
struct{HeartbeatMessageTypetype;//1byte:requestortheresponseuint16payload_length;//2byte:thelengthofthepayloadopaquepayload[HeartbeatMessage.
payload_length];opaquepadding[padding_length];}HeartbeatMessage;Thersteld(1byte)ofthepacketisthetypeinformation,andthesecondeld(2bytes)isthepayloadlength,followedbytheactualpayloadandpaddings.
Thesizeofthepayloadshouldbethesameasthevalueinthepayloadlengtheld,butintheattackscenario,payloadlengthcanbesettoadifferentvalue.
Thefollowingcodesnippetshowshowtheservercopiesthedatafromtherequestpackettotheresponsepacket.
SEEDLabs–HeartbleedAttack6Listing1:ProcesstheHeartbeatrequestpacketandgeneratetheresponsepacket1/*Allocatememoryfortheresponse,sizeis1byte2*messagetype,plus2bytespayloadlength,plus3*payload,pluspadding4*/56unsignedintpayload;7unsignedintpadding=16;/*Useminimumpadding*/89//Readfromtypefieldfirst10hbtype=*p++;/*Afterthisinstruction,thepointer11*pwillpointtothepayload_lengthfield*.
1213//Readfromthepayload_lengthfield14//fromtherequestpacket15n2s(p,payload);/*Functionn2s(p,payload)reads16bits16*frompointerpandstorethevalue17*intheINTvariable"payload".
*/181920pl=p;//plpointstothebeginningofthepayloadcontent2122if(hbtype==TLS1_HB_REQUEST)23{24unsignedchar*buffer,*bp;25intr;2627/*Allocatememoryfortheresponse,sizeis1byte28*messagetype,plus2bytespayloadlength,plus29*payload,pluspadding30*/3132buffer=OPENSSL_malloc(1+2+payload+padding);33bp=buffer;3435//Enterresponsetype,lengthandcopypayload36*bp++=TLS1_HB_RESPONSE;37s2n(payload,bp);3839//copypayload40memcpy(bp,pl,payload);/*plisthepointerwhich41*pointstothebeginning42*ofthepayloadcontent*/4344bp+=payload;4546//Randompadding47RAND_pseudo_bytes(bp,padding);4849//thisfunctionwillcopythe3+payload+paddingbytes50//fromthebufferandputthemintotheheartbeatresponse51//packettosendbacktotherequestclientside.
52OPENSSL_free(buffer);SEEDLabs–HeartbleedAttack753r=ssl3_write_bytes(s,TLS1_RT_HEARTBEAT,buffer,543+payload+padding);55}PleasepointouttheproblemfromthecodeinListing1andprovideasolutiontoxthebug(i.
e.
,whatmodicationisneededtoxthebug).
Youdonotneedtorecompilethecode;justdescribehowyoucanxtheprobleminyourlabreport.
Moreover,pleasecommentonthefollowingdiscussionsbyAlice,Bob,andEvaregardingthefunda-mentalcauseoftheHeartbleedvulnerability:Alicethinksthefundamentalcauseismissingtheboundarycheckingduringthebuffercopy;Bobthinksthecauseismissingtheuserinputvalidation;Evathinksthatwecanjustdeletethelengthvaluefromthepackettosolveeverything.
4SubmissionStudentsneedtosubmitadetailedlabreporttodescribewhattheyhavedoneandwhattheyhaveobserved.
Reportshouldincludetheevidencestosupporttheobservations.
Evidencesincludepackettraces,screendumps,etc.
References[1]Heartbleedattack-Implementation:https://alexandreborgesbrazil.
les.
wordpress.
com/2014/04/hearbleedattackversiona1.
pdf[2]Heartbleedattack-Interestingexplanation:http://xkcd.
com/1354/
ThedevelopmentofthisdocumentwaspartiallyfundedbytheNationalScienceFoundationunderAwardNo.
1303306and1318814.
ThisworkislicensedunderaCreativeCommonsAttribution-NonCommercial-ShareAlike4.
0InternationalLicense.
Ahuman-readablesummaryof(andnotasubstitutefor)thelicenseisthefollowing:Youarefreetocopyandredistributethematerialinanymediumorformat.
Youmustgiveappropriatecredit.
Ifyouremix,transform,orbuilduponthematerial,youmustdistributeyourcontributionsunderthesamelicenseastheoriginal.
Youmaynotusethematerialforcommercialpurposes.
1OverviewTheHeartbleedbug(CVE-2014-0160)isasevereimplementationawintheOpenSSLlibrary,whichen-ablesattackerstostealdatafromthememoryofthevictimserver.
Thecontentsofthestolendatadependonwhatisthereinthememoryoftheserver.
Itcouldpotentiallycontainprivatekeys,TLSsessionkeys,usernames,passwords,creditcards,etc.
ThevulnerabilityisintheimplementationoftheHeartbeatprotocol,whichisusedbySSL/TLStokeeptheconnectionalive.
Theobjectiveofthislabisforstudentstounderstandhowseriousthisvulnerabilityis,howtheattackworks,andhowtoxtheproblem.
TheaffectedOpenSSLversionrangeisfrom1.
0.
1to1.
0.
1f.
TheversioninourUbuntuVMis1.
0.
1.
2LabEnvironmentInthislab,weneedtosetuptwoVMs:onecalledattackermachineandtheothercalledvictimserver.
Weusethepre-builtSEEDUbuntu12.
04VM.
TheVMsneedtousetheNAT-Networkadapterforthenetworksetting.
ThiscanbedonebygoingtotheVMsettings,pickingNetwork,andclickingtheAdaptortagtoswitchtheadaptertoNAT-Network.
MakesurebothVMsareonthesameNAT-Network.
ThewebsiteusedinthisattackcanbeanyHTTPSwebsitethatusesSSL/TLS.
However,sinceitisillegaltoattackarealwebsite,wehavesetupawebsiteinourVM,andconducttheattackonourownVM.
Weuseanopen-sourcesocialnetworkapplicationcalledELGG,andhostitinthefollowingURL:https://www.
heartbleedlabelgg.
com.
Weneedtomodifythe/etc/hostsleontheattackermachinetomaptheservernametotheIPad-dressoftheserverVM.
Searchthefollowinglinein/etc/hosts,andreplacetheIPaddress127.
0.
0.
1withtheactualIPaddressoftheserverVMthathoststheELGGapplication.
127.
0.
0.
1www.
heartbleedlabelgg.
com3LabTasksBeforeworkingonthelabtasks,youneedtounderstandhowtheheartbeatprotocolworks.
Theheartbeatprotocolconsistsoftwomessagetypes:HeartbeatRequestpacketandHeartbeatResponsepacket.
ClientsendsaHeartbeatRequestpackettotheserver.
Whentheserverreceivesit,itsendsbackacopyofthereceivedmessageintheHeartbeatResponsepacket.
Thegoalistokeeptheconnectionalive.
TheprotocolisillustratedinFigure1.
SEEDLabs–HeartbleedAttack2Figure1:OverviewoftheHeartbeatProtocol3.
1Task1:LaunchtheHeartbleedAttack.
Inthistask,studentswilllaunchtheHeartbleedattackonoursocialnetworksiteandseewhatkindofdamagescanbeachieved.
TheactualdamageoftheHeartbleedattackdependsonwhatkindofinformationisstoredintheservermemory.
Iftherehasnotbeenmuchactivityontheserver,youwillnotbeabletostealusefuldata.
Therefore,weneedtointeractwiththewebserveraslegitimateusers.
LetusdoitastheSEEDLabs–HeartbleedAttack3administrator,anddothefollowings:Visithttps://www.
heartbleedlabelgg.
comfromyourbrowser.
Loginasthesiteadministrator.
(UserName:admin;Password:seedelgg)AddBobyasfriend.
(GotoMore->MembersandclickBoby->AddFriend)SendBobyaprivatemessage.
Afteryouhavedoneenoughinteractionaslegitimateusers,youcanlaunchtheattackandseewhatinformationyoucangetoutofthevictimserver.
WritingtheprogramtolaunchtheHeartbleedattackfromscratchisnoteasy,becauseitrequiresthelow-levelknowledgeoftheHeartbeatprotocol.
Fortunately,otherpeoplehavealreadywrittentheattackcode.
Therefore,wewillusetheexistingcodetogainrst-handexperienceintheHeartbleedattack.
Thecodethatweuseiscalledattack.
py,whichwasoriginallywrittenbyJaredStafford.
Wemadesomesmallchangestothecodeforeducationalpurposes.
Youcandownloadthecodefromthelab'swebsite,changeitspermissionsotheleisexecutable.
Youcanthenruntheattackcodeasfollows:$.
/attack.
pywww.
heartbleedlabelgg.
comYoumayneedtoruntheattackcodemultipletimestogetusefuldata.
Tryandseewhetheryoucangetthefollowinginformationfromthetargetserver.
Usernameandpassword.
User'sactivity(whattheuserhasdone).
Theexactcontentoftheprivatemessage.
ForeachpieceofsecretthatyoustealfromtheHeartbleedattack,youneedtoshowthescreen-dumpastheproofandexplainhowyoudidtheattack,andwhatyourobservationsare.
3.
2Task2:FindtheCauseoftheHeartbleedVulnerabilityInthistask,studentswillcomparetheoutcomeofthebenignpacketandthemaliciouspacketsentbytheattackercodetondoutthefundamentalcauseoftheHeartbleedvulnerability.
TheHeartbleedattackisbasedontheHeartbeatrequest.
Thisrequestjustsendssomedatatotheserver,andtheserverwillcopythedatatoitsresponsepacket,soallthedataareechoedback.
Inthenormalcase,supposethattherequestincludes3bytesofdata"ABC",sothelengtheldhasavalue3.
Theserverwillplacethedatainthememory,andcopy3bytesfromthebeginningofthedatatoitsresponsepacket.
Intheattackscenario,therequestmaycontain3bytesofdata,butthelengtheldmaysay1003.
Whentheserverconstructsitsresponsepacket,itcopiesfromthestartingofthedata(i.
e.
"ABC"),butitcopies1003bytes,insteadof3bytes.
Theseextra1000typesobviouslydonotcomefromtherequestpacket;theycomefromtheserver'sprivatememory,andtheymaycontainotheruser'sinformation,secretkeys,password,etc.
Inthistask,wewillplaywiththelengtheldoftherequest.
First,let'sunderstandhowtheHeartbeatresponsepacketisbuiltfromFigure2.
WhentheHeartbeatrequestpacketcomes,theserverwillparsethepackettogetthepayloadandthePayloadlengthvalue(whichishighlightedinFigure2).
Here,thepayloadisonlya3-bytestring"ABC"andthePayloadlengthvalueisexactly3.
Theserverprogramwillblindlytakethislengthvaluefromtherequestpacket.
ItthenbuildstheresponsepacketbypointingtoSEEDLabs–HeartbleedAttack4Figure2:TheBenignHeartbeatCommunicationFigure3:TheHeartbleedAttackCommunicationthememorystoring"ABC"andcopyPayloadlengthbytestotheresponsepayload.
Inthisway,theresponsepacketwouldcontaina3-bytestring"ABC".
WecanlaunchtheHeartBleedattacklikewhatisshowninFigure3.
Wekeepthesamepayload(3bytes),butsetthePayloadlengtheldto1003.
TheserverwillagainblindlytakethisPayloadlengthvaluewhenbuildingtheresponsepacket.
Thistime,theserverprogramwillpointtothestring"ABC"andcopy1003bytesfromthememorytotheresponsepacketasapayload.
Besidesthestring"ABC",theextra1000bytesarecopiedintotheresponsepacket,whichcouldbeanythingfromthememory,suchassecretactivity,logginginformation,passwordandsoon.
OurattackcodeallowsyoutoplaywithdifferentPayloadlengthvalues.
Bydefault,thevalueissettoaquitelargeone(0x4000),butyoucanreducethesizeusingthecommandoption"-l"(letterell)SEEDLabs–HeartbleedAttack5or"--length"asshowninthefollowingexamples:$.
/attack.
pywww.
heartbleedlabelgg.
com-l0x015B$.
/attack.
pywww.
heartbleedlabelgg.
com--length83Yourtaskistoplaywiththeattackprogramwithdifferentpayloadlengthvaluesandanswerthefollow-ingquestions:Question2.
1:Asthelengthvariabledecreases,whatkindofdifferencecanyouobserveQuestion2.
2:Asthelengthvariabledecreases,thereisaboundaryvaluefortheinputlengthvari-able.
Atorbelowthatboundary,theHeartbeatquerywillreceivearesponsepacketwithoutattachinganyextradata(whichmeanstherequestisbenign).
Pleasendthatboundarylength.
Youmayneedtotrymanydifferentlengthvaluesuntilthewebserversendsbackthereplywithoutextradata.
Tohelpyouwiththis,whenthenumberofreturnedbytesissmallerthantheexpectedlength,thepro-gramwillprint"ServerprocessedmalformedHeartbeat,butdidnotreturnanyextradata.
"3.
3Task3:CountermeasureandBugFixToxtheHeartbleedvulnerability,thebestwayistoupdatetheOpenSSLlibrarytothenewestversion.
Thiscanbeachievedusingthefollowingcommands.
Itshouldbenotedthatonceitisupdated,itishardtogobacktothevulnerableversion.
Therefore,makesureyouhavenishedtheprevioustasksbeforedoingtheupdate.
YoucanalsotakeasnapshotofyourVMbeforetheupdate.
#sudoapt-getupdate#sudoapt-getupgradeTask3.
1TryyourattackagainafteryouhaveupdatedtheOpenSSLlibrary.
Pleasedescribeyourobser-vations.
Task3.
2TheobjectiveofthistaskistogureouthowtoxtheHeartbleedbuginthesourcecode.
ThefollowingC-stylestructure(notexactlythesameasthesourcecode)istheformatoftheHeartbeatrequest/responsepacket.
struct{HeartbeatMessageTypetype;//1byte:requestortheresponseuint16payload_length;//2byte:thelengthofthepayloadopaquepayload[HeartbeatMessage.
payload_length];opaquepadding[padding_length];}HeartbeatMessage;Thersteld(1byte)ofthepacketisthetypeinformation,andthesecondeld(2bytes)isthepayloadlength,followedbytheactualpayloadandpaddings.
Thesizeofthepayloadshouldbethesameasthevalueinthepayloadlengtheld,butintheattackscenario,payloadlengthcanbesettoadifferentvalue.
Thefollowingcodesnippetshowshowtheservercopiesthedatafromtherequestpackettotheresponsepacket.
SEEDLabs–HeartbleedAttack6Listing1:ProcesstheHeartbeatrequestpacketandgeneratetheresponsepacket1/*Allocatememoryfortheresponse,sizeis1byte2*messagetype,plus2bytespayloadlength,plus3*payload,pluspadding4*/56unsignedintpayload;7unsignedintpadding=16;/*Useminimumpadding*/89//Readfromtypefieldfirst10hbtype=*p++;/*Afterthisinstruction,thepointer11*pwillpointtothepayload_lengthfield*.
1213//Readfromthepayload_lengthfield14//fromtherequestpacket15n2s(p,payload);/*Functionn2s(p,payload)reads16bits16*frompointerpandstorethevalue17*intheINTvariable"payload".
*/181920pl=p;//plpointstothebeginningofthepayloadcontent2122if(hbtype==TLS1_HB_REQUEST)23{24unsignedchar*buffer,*bp;25intr;2627/*Allocatememoryfortheresponse,sizeis1byte28*messagetype,plus2bytespayloadlength,plus29*payload,pluspadding30*/3132buffer=OPENSSL_malloc(1+2+payload+padding);33bp=buffer;3435//Enterresponsetype,lengthandcopypayload36*bp++=TLS1_HB_RESPONSE;37s2n(payload,bp);3839//copypayload40memcpy(bp,pl,payload);/*plisthepointerwhich41*pointstothebeginning42*ofthepayloadcontent*/4344bp+=payload;4546//Randompadding47RAND_pseudo_bytes(bp,padding);4849//thisfunctionwillcopythe3+payload+paddingbytes50//fromthebufferandputthemintotheheartbeatresponse51//packettosendbacktotherequestclientside.
52OPENSSL_free(buffer);SEEDLabs–HeartbleedAttack753r=ssl3_write_bytes(s,TLS1_RT_HEARTBEAT,buffer,543+payload+padding);55}PleasepointouttheproblemfromthecodeinListing1andprovideasolutiontoxthebug(i.
e.
,whatmodicationisneededtoxthebug).
Youdonotneedtorecompilethecode;justdescribehowyoucanxtheprobleminyourlabreport.
Moreover,pleasecommentonthefollowingdiscussionsbyAlice,Bob,andEvaregardingthefunda-mentalcauseoftheHeartbleedvulnerability:Alicethinksthefundamentalcauseismissingtheboundarycheckingduringthebuffercopy;Bobthinksthecauseismissingtheuserinputvalidation;Evathinksthatwecanjustdeletethelengthvaluefromthepackettosolveeverything.
4SubmissionStudentsneedtosubmitadetailedlabreporttodescribewhattheyhavedoneandwhattheyhaveobserved.
Reportshouldincludetheevidencestosupporttheobservations.
Evidencesincludepackettraces,screendumps,etc.
References[1]Heartbleedattack-Implementation:https://alexandreborgesbrazil.
les.
wordpress.
com/2014/04/hearbleedattackversiona1.
pdf[2]Heartbleedattack-Interestingexplanation:http://xkcd.
com/1354/
- tasksubuntu12.04相关文档
- 谈判ubuntu12.04
- 濮阳市政府采购招标文件编号:PC[2017]164----豫盛华采字GK第102号货物类公开招标文件项目名称:物联网实训室设备
- individualubuntu12.04
- TXubuntu12.04
- 语料ubuntu12.04
- updatedubuntu12.04
速云：深圳独立服务器,新品上线,深港mpls免费体验,多重活动!
速云怎么样?速云是一家国人商家。速云商家主要提供广州移动、深圳移动、广州茂名联通、香港HKT等VDS和独立服务器。目前，速云推出深圳独服优惠活动，机房为深圳移动机房，购买深圳服务器可享受5折优惠，目前独立服务器还支持申请免费试用，需要提交工单开通免费体验试用，次月可享受永久8折优惠，也是需工单申请哦！点击进入：速云官方网站地址活动期限至 2021年7月22日速云云服务器优惠活动：活动1：新购首月可...
georgedatacenter39美元/月$20/年/洛杉矶独立服务器美国VPS/可选洛杉矶/芝加哥/纽约/达拉斯机房/
georgedatacenter这次其实是两个促销，一是促销一款特价洛杉矶E3-1220 V5独服，性价比其实最高；另外还促销三款特价vps，georgedatacenter是一家成立于2019年的美国VPS商家，主营美国洛杉矶、芝加哥、达拉斯、新泽西、西雅图机房的VPS、邮件服务器和托管独立服务器业务。georgedatacenter的VPS采用KVM和VMware虚拟化，可以选择windows...
UCloud：美国云服务器,洛杉矶节点大促,低至7元起/1个月
ucloud美国云服务器怎么样?ucloud是国内知名云计算品牌服务商家，目前推出全球多地机房的海外云服务器。UCloud主打的优势是海外多机房，目前正在进行的2021全球大促活动参与促销的云服务器机房就多达18个。UCloud新一代旗舰产品快杰云服务器已上线洛杉矶节点，覆盖北美和亚太地区，火热促销中， 首月低至7元，轻松体验具备优秀性能与极高性价比的快杰云服务器。点击进入：ucloud美国洛杉矶...
ubuntu12.04为你推荐
-
美国互联网瘫痪网络中断会对美国军力造成什么影响蓝色骨头手机谁有崔健执导的电影《蓝色的骨头》。关键字关键词编故事www.kkk.comwww.kkk103.com网站产品质量有保证吗罗伦佐娜手上鸡皮肤怎么办,维洛娜毛周角化修复液百度指数词什么是百度指数抓站工具一起来捉妖神行抓妖辅助工具都有哪些？汴京清谈都城汴京，数百万家，尽仰石炭，无一燃薪者的翻译莱姿蔓不蔓不枝的蔓是什么意思长房娇为什么我的乳晕颜色会越来越深呢？