Overview of Information Security Elisa Bertino CERIAS and CS ECE Departments Purdue University Elisa Bertino Pag 1 Purdue University Outline Information Security basic concepts Privacy basic concepts and comparison with security Access control security policies and models Access control policies the matrix model and the safety problem discretionary access control mandatory access control role based and task based access control context based access control chinese wall access control Administration policies Elisa Bertino Pag 2 Purdue University Information Security Basic Concepts Elisa Bertino Pag 3 Purdue University Information Protection Why Information are an important strategic and operational asset for any organization Damages and misuses of information affect not only a single user or an application they may have disastrous consequences on the entire organization Additionally the advent of the Internet as well as networking capabilities has made the access to information much easier Elisa Bertino Pag 4 Purdue University Information Security Main Requirements Confidentiality Information Security Integrity Availability Elisa Bertino Pag 5 Purdue University Information Security Examples Consider a payroll database in a corporation it must be ensured that salaries of individual employees are not disclosed to arbitrary users of the database salaries are modified by only those individuals that are properly authorized paychecks are printed on time at the end of each pay period Elisa Bertino Pag 6 Purdue University Information Security Examples In a military environment it is important that the target of a missile is not given to an unauthorized user the target is not arbitrarily modified the missile is launched when it is fired Elisa Bertino Pag 7 Purdue University Information Security main requirements Confidentiality it refers to information protection from unauthorized read operations the term privacy is often used when data to be protected refer to individuals Integrity it refers to information protection from modifications it involves several goals Assuring the integrity of information with respect to the original information relevant especially in web environment often referred to as authenticity Protecting information from unauthorized modifications Protecting information from incorrect modifications referred to as semantic integrity Availability it ensures that access to information is not denied to authorized subjects Elisa Bertino Pag 8 Purdue University Information Security additional requirements Information Quality it is not considered traditionally as part of information security but it is very relevant Completeness it refers to ensure that subjects receive all information they are entitled to access according to the stated security policies Elisa Bertino Pag 9 Purdue University Classes of Threats Disclosure Snooping Trojan Horses Deception Modification spoofing repudiation of origin denial of receipt Disruption Modification Usurpation Modification spoofing delay denial of service Elisa Bertino Pag 10 Purdue University Goals of Security Prevention Prevent attackers from violating security policy Detection Detect attackers violation of security policy Recovery Stop attack assess and repair damage Continue to function correctly even if attack succeeds Elisa Bertino Pag 11 Purdue University Information Security How Information must be protected at various levels The operating system The network The data management system Physical protection is also important Elisa Bertino Pag 12 Purdue University Information Security Mechanisms Confidentiality is enforced by the access control mechanism Integrity is enforced by the access control mechanism and by the semantic integrity constraints Availability is enforced by the recovery mechanism and by detection techniques for DoS attacks an example of which is query flood Elisa Bertino Pag 13 Purdue University Information Security How Additional mechanisms User authentication to verify the identity of subjects wishing to access the information Information authentication to ensure information authenticity it is supported by signature mechanisms Encryption to protect information when being transmitted across systems and when being stored on secondary storage Intrusion detection to protect against impersonation of legitimate users and also against insider threats Elisa Bertino Pag 14 Purdue University Data vs Information Computer security is about controlling access to information and resources Controlling access to information can sometimes be quite elusive and it is often replaced by the more straightforward goal of controlling access to data The distinction between data and information is subtle but it is also the root of some of the more difficult problems in computer security Data represents information Information is the subjective interpretation of data Elisa Bertino Pag 15 Purdue University Data vs Information Data Physical phenomena chosen by convention to represent certain aspects of our conceptual and real world The meaning we assign to data are called information Data is used to transmit and store information and to derive new information by manipulating the data according to formal rules from P Brinch Hansen Operating Systems Principles Prentice Hall 1973 Elisa Bertino Pag 16 Purdue University Data vs Information Protecting information means to protect not only the data directly representing the information Information must be protected also against transmissions through Covert channels Inference It is typical of database systems It refers to the derivation of sensitive information from non sensitive data Elisa Bertino Pag 17 Purdue University Inference Example Name Sex Programme Units Grade Ave Alma F MBA 8 63 Bill M CS 15 58 Carol F CS 16 70 Don M MIS 22 75 Errol M CS 8 66 Flora F MIS 16 81 Gala F MBA 23 68 Homer M CS 7 50 Igor M MIS 21 70 Elisa Bertino Pag 18 Purdue University Inference Example Assume that there is a policy stating that the average grade of a single student cannot be disclosed however statistical summaries can be disclosed Suppose that an attacker knows that Carol is a female CS student By combining the results of the following legitimate queries Q1 SELECT Count FROM Students WHERE Sex F AND Programme CS Q2 SELECT Avg Grade Ave FROM Students WHERE Sex F AND Programme CS The attacker learns from Q1 that there is only one female student so the value 70 returned by Q2 is precisely her average grade Elisa