“IHAVENOIDEAWHATI’MDOING”–ONTHEUSABILITYOFDEPLOYINGHTTPSKatharinaKrombholz, Wilfried Mayer,MartinSchmiedecker, EdgarWeippl

“IHAVENOIDEAWHATI’MDOING”

“IHAVENOIDEAWHATI’MDOING”

“IHAVENOIDEAWHATI’MDOING”

Motivationand Goals

• ExplorereasonsforTLSmisconfigurations– usabilityfromtheadministrator‘sperspective

• StudyTask:ConfigureHTTPSonApacheo HTTP->HTTPSo InteractionwithCAo Hardeningo Testingo Done!

source: (mis)adventures in setting up HTTPS by Yan Su https://www.youtube.com/watch?v=Q0VdlLG7t1w

UserStudy– TheExpert’sPerspective

• Labstudywith28knowledgeableparticipants• Expertinterviewswith7securityauditors

Let’sEncrypt

• EasestheinteractionwiththeCA• Hardeningandintegrationstillneedstobedoneat

leastonce• Ourstudyfocusesonintegrationandhardening

Methodology- DataCollection

1.Recruitment

Questionnaire

• N=117• Multiple choice• Top 30

candidates were invited to participate in the study

2.Lab

Study

• N=28• Think-aloud

protocol• Bash/browser

history• VM images

3.Post-Study

Questionnaire

• N=28• Open/closed-

ended questions

• Demographics, previous experience

4.Expert

Interviews

• N=7• Semi-

structured interviews

• Ecological validity

LabStudy- Participants

• N=28• Gender:2female,26male• Experiencedadmins:17• configuredTLSbefore:17

DataAnalysis

• Observationprotocols:Qualitativeanalysiswithopen/axial/selectivecoding

• Bash/browserhistory,Apachelogfiles:o Quantitativeanalysiso MetricsbasedonQualy’s SSLTest(gradesA-F)

• Statisticalsignificance

SecurityEvaluation

SecurityEvaluation

• Only4participantsdeployedanAgradeconfiguration(25%)

• 15deployedaBgradeconfiguration(67%)• 4participantsdidnotmanagetodeployanyvalid

configuration

SecurityEvaluation

• Only4participantsdeployedanAgradeconfiguration(25%)

• 15deployedaBgradeconfiguration(67%)• 4participantsdidnotmanagetodeployanyvalid

configuration

(Source: SSLPulse)

SecurityEvaluation

• 2participantsusedself-signedcertificates• Noparticipantschoseakeysizesmallerthan2048

fortheirRSAkey• forwardsecrecy:14• HSTSheaders:11• HPKP:2

TLSDeploymentModel

TLSDeploymentModelLet’s Encrypt

Perceptions of Usability

• Findingthebest-practiceworkflowishard(19)• Misleadingterminology(15)• Weakdefaultconfig (12)

OnlineSources

(P23)

OnlineSources

„Theconfigurationprocess isfiddlyandonehastogoogletonsofpages togetitright.Eventhenone

cannotbesuretohaveagoodconfigurationbecausevulnerabilitiesarediscoveredalmostonaregular

basis.“(P9)

OnlineSources

• Averagenumberofvisitedwebsites:60• Numberofvisitedwebsiteshadnoimpactonthe

quality oftheresultingconfiguration

OnlineSources

• Decision-makingprocessismostlybasedononlinesources

• Noin-depthunderstandingofunderlyingfundamentalso e.g.choosingciphersuites

Impactofpriorexperience

• Thereisanassociationbetweenpriorexperienceandqualityoftheresultingconfiguration

• Noevidencethatpreviousemploymentimpactsconfigurationquality

ConfusingFileStructureandTerminology

• Configuringvirtualhostandportistimeconsuming• Apacheconfig filesareperceivedasconfusingand

asadistractionfromthemaintask• Multipleconfigurationfilesandoptions

MoreUsabilityChallenges

• Higheffortforhardening• Confusion:IsthesitestillreachableviaHTTP?• Findingtherightbalancebetweensecurityand

compatibility

InterviewswithSecurityAuditors

• Goal:confirmtheecologicalvalidity ofourresults• Participants:7securityauditorsfromwell-respected

securityconsultingfirms

InterviewswithSecurityAuditors

• AuditingTLSconnectionso Activatedversions?o Activatedciphersuites?o Certrecognizedbywebbrowsers?o HSTS,keypinningetc.

• Tools:o Qualy’s SSLTesto NMapo Nessusmoduleso OpenVAS

ConfigurationsintheWild

• Configurationswithpoorciphers,nohardening,self-signedcertificates

• TwoauditorshadneverseenHTTPSpublickeypinningduringanaudit

Configurations intheWild

• Administratorswhoare“afraidofusingcrypto”• TLSdeploymentwasnotsufficientlystreamlinedin

companieso Multipleservers– updatedseparatelyo Varyingconfigurations

Compatibility

”Inmostcasesbackwardcompatibilityistheshow-stopperregardingproperTLSconfigurations” (E3)

• ..Sometimesjustamockargument• Butfindingthebestfitishard,evenforexperts

Compatibility

”Inmostcasesbackwardcompatibilityistheshow-stopperregardingproperTLSconfigurations” (E3)

• ..Sometimesjustamockargument• Butfindingthebestfitishard,evenforexperts

Suggestedimprovements

• Let’sEncrypt• Securitybydefault(Caddywebserver)• Compatibilityflags• Guidelines:deployeverythingthatdoesn’timpact

compatibility:e.g.HSTS• HTTPSshouldfullyreplaceHTTP• ConceptofhavingCAsisflawed

Conclusions

• ConfiguringTLSonApacheisachallengingtask,evenforexperiencedusersandweshouldtakethisserious!

• Administratorsstrugglewithimportantsecuritydecisions

• Concernsaremainlydrivenbycompatibility• Hardtofindreliableinformationsources

Questions?

Thankyou!