Security Analysis Part I: Basics

Transcription

1 Security Analysis Part I: Basics Ketil Stølen, SINTEF & UiO October 2,

2 Objectives for Lectures on Security Analysis Classify security concepts Introduce, motivate and explain a basic apparatus for risk management in general and risk analysis in particular Relate risk management to system development Describe the different processes that risk management involve Motivate and illustrate model-driven security risk analysis (or security analysis, for short) Demonstrate the use of risk analysis techniques 2

3 Overview of today What is security? What is risk? What is risk management? What is the relationship to cyber security? What is CORAS? 3

4 What is Security Analysis? Security analysis is a specialized form of risk analysis focusing on security risks 4

5 What is Security? security confidentiality integrity availability accountability Only authorised actors have access to information Only authorised actors can change, create or delete information Authorised actors have access to information they need when they need it It is possible to audit the sequence of events in the system 5

6 Security is more than Technology Security solutions are available but what good is security if no one can use the systems? Security requires more than technical understanding Incidents often of non-technical origin Requires a uniform description of the system as a whole how it is used, the surrounding organisation, etc. 6

7 Security Part of System Development Security is traditionally added as an afterthought Solutions often reactive rather than proactive Security issues often solved in isolation Costly redesign Security not completely integrated Enforcing security only at the end of the development process by preventing certain behaviors...may result in a so useless system that the complete development effort would be wasted [Mantel'01]. It would be desirable to consider security aspects already in the design phase, before a system is actually implemented, since removing security flaws in the design phase saves cost and time [Jürjens'02]. 7

8 Oversettelse av Terminologi asset threat unwanted incident risk vulnerability consequence probability frequency treatment aktivum (noe med verdi) trussel uønsket hendelse risiko sårbarhet konsekvens sannsynlighet frekvens/hyppighet behandling 8

9 Many kinds of risk Contractual risk Economic risk Operational risk Environmental risk Health risk Political risk Legal risk Security risk What is Risk? 9

10 Definition of Risk from ISO Risk: Effect of uncertainty on objectives NOTE 1 An effect is a deviation from the expected positive and/or negative NOTE 2 Objectives can have different aspects (such as financial, health and safety, and environmental goals) and can apply at different levels (such as strategic, organization-wide, project, product and process) NOTE 3 Risk is often characterized by reference to potential events and consequences, or a combination of these NOTE 4 Risk is often expressed in terms of a combination of the consequences of an event (including changes in circumstances) and the associated likelihood of occurrence NOTE 5 Uncertainty is the state, even partial, of deficiency of information related to, understanding or knowledge of an event, its consequence, or likelihood 10

11 What is Risk Management? Risk management: Coordinated activities to direct and control an organization with regard to risk [ISO 31000:2009] Communicate and consult Establish the context Identify risks Estimate risks Evaluate risks Risk assessment Monitor and review Treat risks 11

12 Risk Analysis Involves Determining what can happen, why and how Systematic use of available information to determine the level of risk Prioritization by comparing the level of risk against predetermined criteria Selection and implementation of appropriate options for dealing with risk Communicate and consult Establish the context Identify risks Estimate risks Evaluate risks Treat risks Risk assessment Monitor and review 12

13 Terms Asset Vulnerability Threat Reduced risk Risk Need to introduce risk treatment 13

14 Terms Internet Infected PC Computer running Outlook Vulnerability Unwanted incident Worm - Infected twice per year - Infected mail send to all contacts Risk V Threat Install virus scanner Treatment 14

15 Definitions Asset: Something to which a party assigns value and hence for which the party requires protection Consequence: The impact of an unwanted incident on an asset in terms of harm or reduced asset value Likelihood: The frequency or probability of something to occur Party: An organization, company, person, group or other body on whose behalf a risk analysis is conducted Risk: The likelihood of an unwanted incident and its consequence for a specific asset Risk level: The level or value of a risk as derived from its likelihood and consequence Threat: A potential cause of an unwanted incident Treatment: An appropriate measure to reduce risk level Unwanted incident: An event that harms or reduces the value of an asset Vulnerability: A weakness, flaw or deficiency that opens for, or may be exploited by, a threat to cause harm to or reduce the value of an asset 15

16 Cyberspace, Cybersecurity and Cyber-risk What is new and what are the real challenges? 16

17 Background There are no established definitions of cyberspace or cybersecurity Many authoritative organizations have their own definitions EU, ISO, IEC, ITU-T, NIST, CNSS, The various definitions typically reflect different purposes or interests Information security Critical infrastructure protection Privacy and data protection Societal security Combating of cyber-crime and terrorism 17

18 Motivation and Goals Cybersecurity is a hot topic and a frequently used buzzword Stakeholders want to ensure cybersecurity and protection from cyberrisk At the same time there is lack of terminology consensus and method support Our aim: Define a terminology and identify challenges 18

19 Cyberspace The term cyberspace first appeared in science fiction (novel by William Gibson) 19

20 Cyber-system 20

21 Cyber-physical system 21

22 Summary 22

23 Cybersecurity 23

24 Cybersecurity is related to information security and infrastructure security But cybersecurity is not simply the combination of the two Information security is the protection of confidentiality, integrity and availability of information Infrastructure security and CIP is to prevent the disruption, disabling, destruction or malicious control of critical infrastructures 24

25 Summary 25

26 Cyber-risk 26

27 Summary CORAS 27

28 The Challenge of Measurement 28

29 The Challenge of Uncertainty 29

30 The Challenge of Aggregation 30

31 The Challenge of Black-swans (Nassim N. Taleb) 31

32 Security Analysis Using CORAS 32

33 Overview What is CORAS? Main concepts Process of eight steps Risk modeling Semantics Calculus Tool support Further reading 33

34 What is CORAS? CORAS consists of Method for risk analysis Language for risk modeling Tool for editing diagrams Stepwise, structured and systematic process Directed by assets Concrete tasks with practical guidelines Model-driven Models as basis for analysis Models as documentation of results Based on international standards 34

35 Mandatory Reading Mass Soldal Lund, Bjørnar Solhaug, Ketil Stølen: Chapter 3 "A Guided Tour of the CORAS Method" in the book "Model- Driven Risk Analysis: The CORAS Approach", Springer. The chapter can be downloaded freely. Mass Soldal Lund, Bjørnar Solhaug, Ketil Stølen: Risk Analysis of Changing and Evolving Systems Using CORAS, LNCS 6858, Springer. Pages Le Minh Sang Tran, Bjørnar Solhaug, Ketil Stølen. An approach to select cost-effective risk countermeasures exemplified in CORAS. SINTEF A24343, SINTEF ICT, July