Highlights of Database Security

1. Highlights of Database Security Csci - 5708 Compiled by - Jayant Gupta

2. Outline • Discretionary Access Control • Authorization Graph Model • Extension to Authorization Graph Model • Trojan Horse Attack • Mandatory Access Control • Bell-Lapadula Model • Multi-Level Relational Model • Statistical Database Security

3. Discretionary Access Control • Authorization Graph ModelORSystem R Authorization Model • Tuple (g, s, p, t, go) User s granted privilege by user g on tablet With permissionp Having grant option defined by “go”

4. Authorization Graph Example GRANT select ON account TO Anja AT A WITH GRANT OPTION (implicit System) GRANT select ON account TO Bill AT A WITH GRANT OPTION (executed by Anja) GRANT select ON account TO Cain AT A WITH GRANT OPTION (executed by Anja) GRANT select ON account TO Didi AT A WITH GRANT OPTION (executed by Bill) GRANT select ON account TO Didi AT A WITH GRANT OPTION (executed by Cain) GRANT select ON account TO Bill AT A WITH GRANT OPTION (executed by Didi) REVOKE select ON account FROM Bill AT ACASCADE (executed by Anja) DBMS Security

5. Authorization Graph Example GRANT select ON account TO Anja AT A WITH GRANT OPTION (implicit System) GRANT select ON account TO Bill AT A WITH GRANT OPTION (executed by Anja) GRANT select ON account TO Cain AT A WITH GRANT OPTION (executed by Anja) GRANT select ON account TO Didi AT A WITH GRANT OPTION (executed by Cain) GRANT select ON account TO Didi AT A WITH GRANT OPTION (executed by Bill) GRANT select ON account TO Bill AT A WITH GRANT OPTION (executed by Didi) DBMS Security

6. Authorization Graph REVOKE select ON account FROM Cain AT ACASCADE (executed by Anja) Masters Project - Plan B

7. Extension Non cascading REVOKE.

8. Authorization Graph Source: Database Security and Access Control Methods: A brief overview, Kriti, InduKashyap, IJERT, 2(5), May 2013

9. Revoke Without Cascade With Cascade Source: Database Security and Access Control Methods: A brief overview, Kriti, InduKashyap, IJERT, 2(5), May 2013

10. Trojan Horse Attack-Initial State Source: Database Security and Access Control Methods: A brief overview, Kriti, InduKashyap, IJERT, 2(5), May 2013

11. Trojan Horse Attack-Finished State Source: Database Security and Access Control Methods: A brief overview, Kriti, InduKashyap, IJERT, 2(5), May 2013

12. Mandatory Access Control Bell-Lapadula Model

13. Bell-Lapadula Model • Simple security property • No read-up/Read down • Star Property • No write-down/Write up

14. Bell-Lapadula Model Source: Database Security and Access Control Methods: A brief overview, Kriti, InduKashyap, IJERT, 2(5), May 2013

15. Mandatory Access Control and Role-Based Access Control for Multilevel Security (cont’d.) Source:Elmasri, R.Navathe B. Fundamentals of database systems. Pearson. 7th Ed. • Simple security property • Subject S not allowed read access to object O unless class(S) ≥ class(O) • Star property • Subject not allowed to write an object unless class(S) ≤ class(O) • Prevent information from flowing from higher to lower classifications • Attribute values and tuples considered as data objects

16. Polyinstantiation User with clearance ‘C’ UPDATE EMPLOYEE SETJob_performance = ‘Excellent’ WHERE Name=‘Smith’; Figure 30.2 A multilevel relation to illustrate multilevel security (a) The original EMPLOYEE tuples (b) Appearance of EMPLOYEE after filtering for classification C users (c) Appearance of EMPLOYEE after filtering for classification U users (d) Polyinstantiation of the Smith tuple Source:Elmasri, R.Navathe B. Fundamentals of database systems. Pearson. 7th Ed. Pg 1136.

17. 30.5 Introduction to Statistical Database Security Figure 30.3 The PERSON relation schema for illustrating statistical database security Source:Elmasri, R.Navathe B. Fundamentals of database systems. Pearson. 7th Ed. • Statistical databases used to provide statistics about various populations • Users permitted to retrieve statistical information • Must prohibit retrieval of individual data • Population: set of tuples of a relation (table) that satisfy some selection condition

18. Introduction to Statistical Database Security (cont’d.) Source:Elmasri, R.Navathe B. Fundamentals of database systems. Pearson. 7th Ed. Pg 1147. Only statistical queries are allowed

19. Introduction to Statistical Database Security (cont’d.) Source:Elmasri, R.Navathe B. Fundamentals of database systems. Pearson. 7th Ed. • Preventing the inference of individual information • Provide minimum threshold on number of tuples • Prohibit sequences of queries that refer to the same population of tuples • Introduce slight noise or inaccuracy • Partition the database • Store records in groups of minimum size

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