Data and Applications Security Developments and Directions

1. Data and Applications Security Developments and Directions Dr. Bhavani Thuraisingham The University of Texas at Dallas Lecture #3 Access Control in Database Systems January 24, 2007

2. Outline • Discretionary Access Control in Relational Databases • Mandatory Access Control in Relational Databases • Security Constraints • Types of Access Control • Inference problem, Role-based, Temporal, Usage • Access Control in Other Databases • Objects, Federated • Current Trends in Access Control • Date Warehousing, Semantic Web, Privacy Control • Next Steps in Access Control

3. Access Control in Relational Databases:1975 - Present • Access Control policies were developed initially for file systems • E.g., Read/write policies for files • Access control in databases started with the work in System R and Ingres Projects • Access Control rules were defined for databases, relations, tuples, attributes and elements • SQL and QUEL languages were extended • GRANT and REVOKE Statements • Read access on EMP to User group A Where EMP.Salary < 30K and EMP.Dept <> Security • Query Modification: • Modify the query according to the access control rules • Retrieve all employee information where salary < 30K and Dept is not Security

4. Query Modification Algorithm • Inputs: Query, Access Control Rules • Output: Modified Query • Algorithm: • Given a query Q, examine all the access control rules relevant to the query • Introduce a Where Clause to the query that negates access to the relevant attributes in the access control rules • Example: rules are John does not have access to Salary in EMP and Budget in DEPT • Query is to join the EMP and DEPT relations on Dept # • Modify the query to Join EMP and DEPT on Dept # and project on all attributes except Salary and Budget • Output is the resulting query

5. Mandatory Access Control (MAC) in Databases: 1982- Present • Bell and LaPadula Policy adapted for databases • Read at or above your level and Write at your level; Granularity of classification: Databases, Relations, Tuples, Attributes, Elements • Security Architectures • Operating system providing mandatory access control and DBMS is untrusted with respect to MAC (e.g., SRI’s SeaView) • Trusted Subject Architecture where DBMS is trusted with respect to MAC (e.g., TRW’s ASD and ASD Views) • Integrity Lock where Trusted front-end computes checksums (e.g., MITRE’s MISTRESS Prototype) • Distributed Architecture where data is distributed according to security levels and access through trusted front-end (e.g., NRL’s SINTRA) Extended Kernel for Security Policy Enforcement such as constraints (e.g., Honeywell’s Lock Data Views)

6. Security Constraints / Access Control Rules • Simple Constraint: John cannot access the attribute Salary of relation EMP • Content-based constraint: If relation MISS contains information about missions in the Middle East, then John cannot access MISS • Association-based Constraint: Ship’s location and mission taken together cannot be accessed by John; individually each attribute can be accessed by John • Release constraint: After X is released Y cannot be accessed by John • Aggregate Constraints: Ten or more tuples taken together cannot be accessed by John • Dynamic Constraints: After the Mission, information about the mission can be accessed by John

7. Enforcement of Security Constraints User Interface Manager Constraint Manager Database Design Tool Constraints during database design operation Security Constraints Update Processor: Constraints during update operation Query Processor: Constraints during query and release operations Database Relational DBMS

8. Other Developments in Access Control • Inference Problem and Access Control • Inference problem occurs when users pose queries and deduce unauthorized information from the legitimate responses • Security constraint processing for controlling inferences • More recently there is work on controlling release information instead of controlling access to information • Temporal Access Control Models • Incorporates time parameter into the access control models • Role-based access control • Controlling access based on roles of people and the activities they carry out; Implemented in commercial systems • Positive and Negative Authorizations • Should negative authorizations be explicitly specified? How can conflicts be resolved?

9. Some Examples • Temporal Access Control • After 1/1/05, only doctors have access to medical records • Role-based Access Control • Manager has access to salary information • Project leader has access to project budgets, but he does not have access to salary information • What happens is the manager is also the project leader? • Positive and Negative Authorizations • John has write access to EMP • John does not have read access to DEPT • John does not have write access to Salary attribute in EMP • How are conflicts resolved?

10. Usage Control • Usage Control (UCON) Model goes beyond traditional access control • Developed by Sandhu et al • Consists of the following • Policies of authorizations, Obligations and Conditions • Authorization decisions are determined by policies of the subject, objects and right • Obligations are actions that are required to be performed before or during the access process • Conditions are environment restrictions that are required to be valid before or during the access process • Many policies can be expressed using UCON • Extensions being proposed for temporal usage control

11. Access Control in Other Types of Databases • Object Databases • Controlling access to classes, object instances, instance variables, method execution etc. • E.g., MCC’s ORION model both for discretionary security and mandatory security • Distributed Databases • Extend access control for relational databases to a distributed environment across the nodes • Federated Databases • Integrate security policies exported by the component database systems and form a federated policy • Deductive Databases • Logic for secure data and knowledge base systems – e.g., NTML Non-monotonic Typed Multilevel Logic

12. Access Control in Databases: Current Trends (1996 – Present) • Data Warehousing • Controlling access to aggregate information in the Warehouse • Multimedia Database Systems • Geospatial Information Systems • Web Databases • E-Commerce and Knowledge Management, Collaboration/Workflow • Semantic Web • XML, RDF, Information Integration • Dependable Databases • Real-time/Embedded Database Systems • Sensor/Stream Database Systems

13. Data Warehouse: Data correlating Employees With Travel patterns and Projects Users Query the Warehouse Could be any DBMS e.g., relational Oracle DBMS for Employees Sybase DBMS for Projects Informix DBMS for Travel Data Warehouse Challenge: Controlling access to the Warehouse and at the same time enforcing the access control policies enforced by the back-end Database systems Data Data Data

14. Enforcing Access Control for Data Mining Algorithms • Query the data and extract information previously unknown\ • Whenever data is accessed check the access control rules • Examine the access control rules to determine whether the mined information can be released to the user • Extensions to the Inference problem

15. Access Control for Multimedia Databases • Access Control for Text, Images, Audio and Video • Granularity of Protection • Text • John has access to Chapters 1 and 2 but not to 3 and 4 • Images • John has access to portions of the image • Access control for pixels? • Video and Audio • John has access to Frames 1000 to 2000 • Jane has access only to scenes in US • Security constraints • Association based constraints • E.g., collections of images are classified

16. Access Control for Web Databases • Secure web data management issues include: • Extending traditional security mechanisms for web databases • Access control models • Integrating security policies • Secure query, indexing and transaction management strategies • Security impact for integrating heterogeneous databases • Security specific for the web • Security for unstructured databases such as multimedia, XML and RDF documents • Security impact on Ontology management • Privacy violations due to data mining • Protecting intellectual property, e-payment systems

17. Secure Semantic Web • According to Tim Berners Lee, The Semantic Web supports • Machine readable and understandable web pages • Layers for the semantic web: Security cuts across all layers • Challenge: Not only integrating the layers for the semantic web, but also ensuring secure interoperability Logic, Proof and Trust S E C U R I T Y P R I V A C Y Rules/Query Other Services RDF, Ontologies XML, XML Schemas URI, UNICODE

18. XML Security • Some ideas have evolved from research in secure multimedia/object data management • Access control and authorization models • Protecting entire documents, parts of documents, propagations of access control privileges; Protecting DTDs vs Document instances; Secure XML Schemas • Update Policies and Dissemination Policies • Secure publishing of XML documents • How do you minimize trust for third party publication • Use of Encryption • Inference problem for XML documents • Portions of documents taken together could be sensitive, individually not sensitive

19. Security and Ontologies • Access control for Ontologies • Who can access which parts of the Ontologies • E.g, Professor can access all patents of the department while the Secretary can access only the descriptions of the patents in the patent ontology • Can we apply the research on secure metadata management for secure ontology management? • Ontologies for Security Applications • Use ontologies for specifying security/privacy policies • Integrating heterogeneous policies may involve integrating ontologies and resolving inconsistencies

20. Privacy Constraints / Access Control Rules • Privacy constraints processing • Simple Constraint: an attribute of a document is private • Content-based constraint: If document contains information about X, then it is private • Association-based Constraint: Two or more documents taken together is private; individually each document is public • Release constraint: After X is released Y becomes private • Augment a database system with a privacy controller for constraint processing

21. Integrated Architecture for Privacy Constraint Processing User Interface Manager XML Database Design Tool Constraints during database design operation Constraint Manager Privacy Constraints Update Processor: Constraints during update operation Query Processor: Constraints during query and release operations Relational DBMS Database

22. Federated Data Management Systems for National Security and Privacy Federated Data Mining/Federated Security Policy Export Export Data/Policy Data/Policy Export Data/Policy Component Component Data/Policy for Data/Policy for Agency A Agency C Component Data/Policy for Agency B

23. Other Policies • Trust Policies • To what extent do you trust the source of the data • How can trust be propagated • Adding trust value to each piece of data • A trusts B and B trusts C, does this mean A trusts C? • A department head sends messages to all the faculty; however he/she may not trust a particular person • Developing a language to specify trust • Integrity Policies • Maintaining the quality of the data • Adding an attribute to each piece of data to specify the quality • Quality also depends on how much you trust the source • Algebra for data quality

24. Access Control in Databases: Next Steps • Access Control in Databases will continue to be very important • We also need to examine alternatives • We need new kinds of access control models • 1975 models may not be suitable for emerging applications such as semantic web, e-commerce and stream data management • Role-based access control has become very popular and is implemented now in commercial systems. What variations of this model are appropriate for emerging applications? • End-to-end security is critical • We cannot have secure databases and have insecure networks and middleware; Composability • Flexible security policies • Confidentiality, Authenticity, Completeness, Integrity, Trust, Privacy, Data Quality, etc.