Lecture 1 (2).pdf

Computer System Security: Lecture 1 Dr Tahani Aljohani 1 Lecture 1 overview Computer Security Concepts Threats, Attacks, and Assets Security Functional Requirements Fundamental Security Design Principles Attack Surfaces and Attack Trees Computer Security...

Computer System Security: Lecture 1 Dr Tahani Aljohani 1 Lecture 1 overview Computer Security Concepts Threats, Attacks, and Assets Security Functional Requirements Fundamental Security Design Principles Attack Surfaces and Attack Trees Computer Security Strategy 2  Learning objectives Describe the key security requirements of confidentiality, integrity and availability Discuss the types security threats and attacks that must be dealt with Summarize the functional requirements for computer security Explain the fundamental security design principles Discuss the use of attack surfaces and attack trees Understand the principle aspects of a comprehensive security strategy 3 A definition of computer security Computer security: The protection afforded to an automated information system in order to attain the applicable objectives of preserving the integrity, availability and confidentiality of information system resources (includes hardware, software, firmware, information/data, and telecommunications) NIST EFt1995 oh I ÉJ In owl w 211 awl Cofidentiality Availability D Integrity 25611 mm Hw sw Firmware intodata telecommunications lanai an area 4  Three key objectives (the CIA triad) Confidentiality Key 1 us oumisse se moi on D privacy wsj b Data confidentiality: Assures that confidential information is not jiffIII disclosed to unauthorized individuals j Privacy: Assures that individual control or influence what a information may be collected and stored go.mxautism Data lab base um1 Google IntegrityIf Key 2 i Data integrity: assures that information and programs are changed only in a specified and authorized manner System integrity: Assures that a system performs its operationsfunTna in unimpaired manner sÉ so as Availability: assure that systems works promptly and Key 3 si ai authentication service is not denied to authorized users IAvailabilityy It on em 5 22h win an oxas Key Security Concepts D simi3 it 1 Data 2 Services 6 Other concepts to a complete security picture verified swim know Confident Trusted aetosy Aksum an a Authenticity: the property of being genuine and being able to be verified and trusted; confident in the validity of a transmission, or a message, or its originator Justinian's's www.t.sn im say twenty Accountability: generates the requirement for actions of an entity to be traced uniquely to that individual to support nonrepudiation, deference, fault isolation, etc. D fault nonreputations twos isolation deference www.sawiooses aiy d time em snows 7  obj1158lose 6 Is stasis b taxes in a was Cofidentiality was.ws s j Integrity Availability to sew writ is se Isaia b noisome at zih.owouss.su Cofidentiality msas l h p awesome're new.ws Availability p ease i xnxx.wsta.is simianassetown t Cofidentiality p Integrity p cost was siberian p web sues a a serviceauthentication Availability  Examples of security requirements: Confidentiality 1. Student grade information is an asset whose confidentiality is considered to be very high The US FERPA Act: grades should only be available to students, their parents, and their employers (when required for the job) 2. Student enrollment information: may have moderate confidentiality rating; less damage if enclosed 3. Directory information: low confidentiality rating; often available publicly 1. 2. 3. If Btf High Moderf SAW Loe 9  Examples of security requirements: Integrity Ka e e ren 1. A hospital patient’s allergy information Weg (high integrity data): a doctor should be able to trust that the info is correct and current If a nurse deliberately falsifies the data, the database should be restored to a trusted basis and the falsified information traced back to the person who did it K in a At1 2. An online newsgroup registration data:Mauling moderate level mmmm of integrity 3. An example ofMiggy low integrity requirement: anonymous online poll (inaccuracy is well understood) at hi a e 4 das s I Ea i n 10  Examples of security requirements: Availability 1. imma b availability requirement Iffy A system that provides authentication: high as it If customers cannot access resources, the loss of services could result in financial loss 2. Mulling A public website for a university: a moderate these availably requirement; not critical butmmmm causes waists embarrassment 3. An online telephone directory lookup: a low was unygg availability requirement because unavailability is mostly annoyance (there are alternative sources) 11 mysecurityischallenge insist or t 45.33mi Challenges of computer security 1. Computer security is not simple 2. One must consider potential (unexpected) attacks 1 a 3. Procedures used are often counter-intuitive security 4. Must decide where to deploy mechanisms 5. Involve algorithms and secret info (keys) serenata 6. A battle of wits between attacker / admin 7. It is not perceived on benefit until fails 8. Requires constant monitoring th 9. Too often an after-thought (not integral) was 10. Regarded as impediment to using system 12  ix s s w.ae manyanticantiaeprotoco integrity iman amie.am Anno reset mesingatrain amazons a Computer security terminology are encrypting was.am y evaximent minestrongnow mechanisms.es searitysi o.evssao oas soso.ae bias 14  Threat consequences Unauthorized disclosure: threat to confidentiality so Exposure (release data), interception, inference, intrusion 25 do threat to integrity Deception: 0 Masquerade, falsification (alter data), repudiation or Disruption: threat to integrity and availability Incapacitation (destruction), corruption (backdoor logic), M obstruction (infer with communication, overload a line) Usurpation: threat to integrity Misappropriation (theft of service), misuse (hacker gaining unauthorized access) s asslideI HAD 16  are ins Mitu a r me serverscan cop I a aww communication pattren six msn.am very an nameruse tons in some agoprotectionmechanism authorized entity im soYourlabsystemso g listsso is ow i isone a Gradesail in X GT e six set a an Disabuse i systemcomponents titanosaurs a t disabusesissies two a backdoorlogic e as a time songs on corrupted so a on ti sa eeswitchas sa er si Es na um a Ioana Threat consequences (tabular form) 17  The scope of computer security outgianton outview ist er atan b b as assassin 18  Examples of threats oases Amina E 1 Is as mponent as Kim irons 1 Hw 2 sw 5 Data 4 communication 2 45524 y say g 19  take.rs ltw eirseillb rirseillb ISecurity functional requirements (FIPS IN 200) was 6816 security iwi in rirseilly Rey Functional Management Technical measures Access control; identification & authentication; system & communication protection; system & information integrity Management controls and procedures Awareness & training; audit & accountability; certification, accreditation, & security assessments; contingency planning; maintenance; physical & environmental protection; planning; personnel security; risk assessment; systems & services acquisition Overlapping technical and management Configuration management; incident response; media protection 20  Wh WH s Fundamental security design principles [1/4] Despite years of research, it is still difficult to design systems that comprehensively prevent security flaws But good practices for good design have been documented (analogous to software engineering) Economy of mechanism, fail-safe defaults, complete mediation, open design, separation of privileges, lease privilege, least common mechanism, psychological accountability, isolation, encapsulation, modularity, layering, least astonishment Ipradicis 21 Fundamental security design principles [2/4] ios Hackers it is a test sina.us smallsyseasier to test Economy of mechanism: the design of security measures should be as simple as possible Simpler to implement and to verify Fewer vulnerabilities Accesscontrolbasedon They all allow exceptAli wrong correct Accesscontrolbasedon They allDeniedexceptauthorized Fail-safe default: access decisions should be based on permissions; i.e., the default is lack of access Complete mediation: every access should checked against an access control system tote cashes I I É reading s minor as miss ing Open design: the design should be open rather than secret (e.g., encryption algorithms) what you need to be public makeit public 22 Fundamental security design principles [3/4] Isolation Dataempathy to set Public access should be isolated from critical resources (no connection between public and critical information) Users files should be isolated from one another (except when desired) Security mechanism should be isolated (i.e., preventing access to those mechanisms) Encapsulation: similar to object concepts (hide internal structures) based on oop Jodl Modularity: modular structure A gaim to owe functions components a 23  Fundamental security design principles [4/4] people Layering (defense in depth): use of multiple, usersroot a in overlapping protection approaches Least astonishment: a program or interface should always respond in a way that is least likely to astonish a user me ok as a Y IE I wi i n HELLO I 24 Fundamental security design principles dis wi d stay 46 win d c all twish J is p I 6 it int d int g p moss s bl u w Separation of privilege: multiple privileges should be needed to do achieve access (or complete a task) Least privilege: every user (process) should have the least privilege to perform a task www 214 N d car eww In HD to lung Least common mechanism: a design should minimize the function shared by different users (providing mutual security; reduce deadlock) Psychological acceptability: security mechanisms should not interfere unduly with the work of users asix main can em ti u ped Transparency 25  Attack surfaces testy Attack surface: the reachable and exploitable vulnerabilities in a system Open ports b Eg I Services outside a firewall I An employee with access to sensitive info 52 … Three categories Network attack surface (i.e., network vulnerability) Software attack surface (i.e., software vulnerabilities) Human attack surface (e.g., social engineering) Jose 3 I a category Attack analysis: assessing the scale and severity of threats 26  Attack trees A branching, hierarchical data structure that represents a set of potential vulnerabilities Objective: to effectively exploit the info available on attack patterns published on CERT or similar forums Security analysts can use the tree to guide design and strengthen countermeasures 27  thatstoredatunsafeplace document 1,444,14 1 Root objective root 2 Howtoachieveit areas ladies 3 g IKEA o new IDEA IDEA IDEA  Computer security strategy An overall strategy for providing security Policy (specs): what security schemes are supposed to do Assets and their values Potential threats Ease of use vs security ksystemforstudent rsecure itontomakeit Cost of security vs cost of failure/recovery 1policy on based requirement a pongto write me so Implementation/mechanism: how to enforce preserving aminimum mains amea snare race be and out by accessed thestudent toknow need p eople Prevention confidentiality sma 2thesystem no be asac avan availability Detection 2Mechanism Response a emotion up aBan Recovery sassurance Correctness/assurance: does it really work (validation/review) 29  Summary Security concepts Terminology Functional requirements Security design principles Security strategy 30 References Lecture slides prepared from Dr Lawrie Brown (UNSW@ADFA) for “Computer Security: Principles and Practice”, 1/e, by William Stallings and Lawrie Brown, Chapter 1 “Overview”. 31