CS475 – Network and Information Security Lecture 1 Introduction Elias Athanasopoulos [email protected]
Whatisthiscourseallabout?
• Understandthefundamentalconceptsofsecurityinsoftware,systems,andthenetwork
• Broadrangeofsecuritytopics• Noverydeepdives• Hands-onexperience
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Whyitsocomplicated?
• Systemshavedifferentbuildinglayers– Hardware,Software,Network,Protocols
• Heavyinterractionandinterconnection– InternetofThings
• People
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Ourtopics
• AppliedCrypto• SoftwareSecurity• NetworkSecurity• WebSecurity• MobileSecurity• AnonymityandPrivacy
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Conceptsofdifferenttopicsinterractwitheachother!
Resources• Nosingletextbooktocovereverything,thetopicisrapidly
changing• Iwillprovidemanyresourcesonaper-lecturebasis
(papers,articles,software,etc.)• Somesuggested(free)material:
– HandbookofAppliedCryptography,http://cacr.uwaterloo.ca/hac/
– SecurityEngineering,http://www.cl.cam.ac.uk/~rja14/book.html
• Somesuggested(nonfree)material:– IntroductiontoComputerSecurity,byMichaelT.Goodrichand
RobertoTamassia(ISBN-13:978-0321512949,ISBN-10:0321512944)
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Whatiscomputersecurity?“Computersecurity,alsoknownascybersecurity orITsecurity,istheprotectionofcomputer systemsfromthetheft ordamage totheirhardware,softwareorinformation,aswellasfromdisruption ormisdirection oftheservicestheyprovide.”
Gasser,Morrie(1988).BuildingaSecureComputerSystem(PDF).VanNostrandReinhold.p. 3.ISBN 0-442-23022-2,https://ece.uwaterloo.ca/~vganesh/TEACHING/S2014/ECE458/building-secure-systems.pdf)
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Whatiscomputersecurity?• Apropertythataffectssystems– Hardware,software,network
• Degradingthispropertyleadstobadthings– Theft,damage,disruption,misdirection
• Degradingthispropertyisdeliberate– Anattackerdegradesthesecurityofasystemonpurpose
Suggestedreadhttps://www.cs.columbia.edu/~smb/blog/2017-09/2017-09-01.html
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Example1
• Anapplicationneedstotransmitsensitivedata– Submittingapassword– Sendingapersonalmessage
• Justreadingsensitivedataisenoughtobreaksecurity– Leakthepassword,orthepersonalmessage
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Example2
• Anapplicationneedstotransmitsensitivedata– Submitthedetailsofafinancialtransaction– Submitthecastingofavote
• Modifyingthesensitivedatacanbreakthesecurity–Modifythefinancialtransaction,orthevote
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SecurityRequirements
• FromExample1and2,wecanseethatsecuritycanimplyseveraldifferent sub-properties
• Differentapplicationshavedifferentsecurityrequirements,whichcanbegrouped– Confidentiality,Integrity,Availability,Authentication,Non-repudiation,Accounting,Privacy
– Suggestedreference:https://www.ietf.org/rfc/rfc2828.txt
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Confidentiality
Thepropertythatinformationisnotmadeavailableordisclosedtounauthorizedindividuals,entities,orprocesses(i.e.,toanyunauthorizedsystementity)
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Integrity
Dataintegrity:Thepropertythatdatahasnotbeenchanged,destroyed,orlostinanunauthorizedoraccidentalmannerSystemintegrity:Assuresthatasystemperformsitsintendedfunctioninanunimpairedmanner,freefromdeliberateorinadvertentunauthorizedmanipulationofthesystem
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Availability
Thepropertyofasystemorasystemresourcebeingaccessibleandusableupondemandbyanauthorizedsystementity,accordingtoperformancespecificationsforthesystem;i.e.,asystemisavailableifitprovidesservicesaccordingtothesystemdesignwheneverusersrequestthem
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CIA• Confidentiality
– Thepropertythatinformationisnotmadeavailableordisclosedtounauthorizedindividuals,entities,orprocesses(i.e.,toanyunauthorizedsystementity)
• Integrity– Dataintegrity:Thepropertythatdatahasnotbeenchanged,destroyed,or
lostinanunauthorizedoraccidentalmanner– Systemintegrity:Assuresthatasystemperformsitsintendedfunctioninan
unimpairedmanner,freefromdeliberateorinadvertentunauthorizedmanipulationofthesystem
• Availability– Thepropertyofasystemorasystemresourcebeingaccessibleandusable
upondemandbyanauthorizedsystementity,accordingtoperformancespecificationsforthesystem;i.e.,asystemisavailableifitprovidesservicesaccordingtothesystemdesignwheneverusersrequestthem
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AnExample
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Confidentiality:Badguyscannotseemessages
Integrity: Badguyscannotchange
messages
Availability: Thesystemisoperational
System/ServiceCommunication
Example1– Confidentiality
• Anapplicationneedstotransmitsensitivedata– Submittingapassword– Sendingapersonalmessage
• Justreadingsensitivedataisenoughtobreaksecurity– Leakthepassword,orthepersonalmessage
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Example2– Integrity
• Anapplicationneedstotransmitsensitivedata– Submitthedetailsofafinancialtransaction– Submitthecastingofavote
• Modifyingthesensitivedatacanbreakthesecurity–Modifythefinancialtransaction,orthevote
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AdditionalRequirements
• Non-repudiation– Onepartyofatransactioncannotdenyhavingreceivedatransactionnorcantheotherpartydenyhavingsentatransaction
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AdditionalRequirements
• AccessControl– Identification• IclaimIamJohnSmith(i.e.,bysubmittingausername)
– Authentication• SystemverifiesthatIamJohnSmith(e.g.,throughpassword)
– Authorization• AsJohnSmithIamauthorizedtoperformaparticularaction(i.e.,postamessage)
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Privacy
Therightofanentity(normallyaperson),actinginitsownbehalf,todeterminethedegreetowhichitwillinteractwithitsenvironment,includingthedegreetowhichtheentityiswillingtoshareinformationaboutitselfwithothers
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SecurityContext
• ThreatModel– Listtheattacker’scapabilities– Listtheattacker’sgoal– Often,listthedefensesthatareinplace– Often,listtheaffectedrisksofthetargetsystemusingsecurityrequirements(CIA)
“Securityisn’tascalar.Itdoesn’tmakesensetoask‘IsdeviceXsecure?’withoutacontext:‘secureagainstwhomandinwhatenvironment?’”
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ExampleThreatModel
• PassiveMan-in-the-Middle– Anattackerthatcanpassivelymonitornetworkpacketsexchangedbetweentwoparties
– Attackerwantstorevealtheconversation– ConversationisencryptedusingthecryptosystemX
– ConfidentialitycanbeaffectedifattackercanbreakcryptosystemX
– Integrity,andAvailabilitycannotbeaffected
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Ethics
• Thecoursehasmanyoffensiveparts• Usingtheoffensivepartinthewildisstrictlyforbidden
• Ourgoalistounderstandattacksforbuildingbetterdefenses
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