Database Security and Authorization By Yazmin Escoto Rodriguez Christine Tannuwidjaja

Main Types of Security:  Enforce security of portions of a database against unauthorized access  - Database Security and Authorization Subsystem  Prevent unauthorized persons from accessing the system itself  - Access Control  Control the access to statistical databases  - Statistical Database Security  Protect sensitive data that is being transmitted via some type of communications  - Data Encryption

Database Security and Authorization Subsystem  Discretionary Security Mechanisms - concerned with defining, modeling, and enforcing access to information  Mandatory Security Mechanisms for Multilevel Security - requires that data items and users are assigned to certain security labels

Mandatory Access Control Elements: OBJECTS CLASSIFICATIONS -- class(o)-- SUBJECTS CLEARANCE --clear(s)-- Levels : Top Secret, Secret, Confidential, Unclassified

Mandatory Access Control Rules:  Simple Property: subject s is allowed to read data item d if clear(s) ≥ class(d)  *-property: subject s is allowed to write data item d if clear(s) ≤ class(d)  Simple Property protects information from unauthorized access  *-property protects data from contamination or unauthorized modification

Multilevel Security Databases- example Set up: we have: - subject x with clear(x) = TS - subject y with clear(y) = S - subject z with clear(z) = U Project NameTopicLocationTC Black, TSDatabases, TSLos Angeles, TSTS Silver, SSupply Chain, SNew York, SS Gold, UInventories, SAtlanta, SS Indigo, UTelecommunication, UAustin, UU

Multilevel Security Databases- example Project NameTopicLocationTC Black, TSDatabases, TSLos Angeles, TSTS Silver, SSupply Chain, SNew York, SS Gold, UInventories, SAtlanta, SS Indigo, UTelecommunication, UAustin, UU Project NameTopicLocationTC Silver, SSupply Chain, SNew York, SS Gold, UInventories, SAtlanta, SS Indigo, UTelecommunication, UAustin, UU

Multilevel Security Databases- example Project NameTopicLocationTC Black, TSDatabases, TSLos Angeles, TSTS Silver, SSupply Chain, SNew York, SS Gold, UInventories, SAtlanta, SS Indigo, UTelecommunication, UAustin, UU Project NameTopicLocationTC Gold, U-, U U Indigo, UTelecommunication, UAustin, UU

Multilevel Security Databases- example  subject z wants to insert the next tuple Project NameTopicLocationTC Black, TSDatabases, TSLos Angeles, TSTS Silver, SSupply Chain, SNew York, SS Gold, UInventories, SAtlanta, SS Indigo, UTelecommunication, UAustin, UU Silver, ULinear Programming, UOmaha, UU Polyinstantiation : the existence of multiple data objects with the same key

Multilevel Security Databases- example Project NameTopicLocationTC Gold, U-, U U Indigo, UTelecommunication, UAustin, UU  subject z wants to replace the null values with certain data items Project NameTopicLocationTC Black, TSDatabases, TSLos Angeles, TSTS Silver, SSupply Chain, SNew York, SS Gold, UInventories, SAtlanta, SS Indigo, UTelecommunication, UAustin, UU Gold, UMarkov Chain, UNew Jersey, UU

Security Relevant Knowledge Entity Relationship -- describes the structural part of the database Data Flow Diagram -- represents the functions the system should perform Classification Constraints To assign to security classifications concepts of schemas: - ones that classify items - ones that classify query results

System Object What is it? Entity type Specialization type Relationship type In security it is the target of protection Notation O(A 1..,A n ) - A i (i=1..N) is an attribute and is defined over domain D i Has an identity property (key attributes) A ⊆ (A 1,..,A n )

Multilevel Secure Application MAJOR QUESTION: Which way should the attributes and occurrences of O be assigned to proper security classifications? CLASSIFICATION RESULT: Security object O  multilevel security object O m Performed by means of security constraints

Graphical Extensions to the ER N X P (U)(Co)(S) [U..S][Co..TS] (TS) Secrecy Levels Ranges of Secrecy Levels Aggregation leading to TS (N..constant) Inference leading to Co Evaluation of predicate P Security dependency

SSN Name Dep Salary Title Function SSN Date Client Subject EmployeeProject Is Assigned to (0,N)(0,M) ER Diagram

Object Classification Constraints – Simple Constraints Let X be a set of attributes of security object O (X ⊆ {A 1,…,A n }) SiC (O(X))=C, (C ∈ SL) Results in a multilevel object O m (A 1, C 1,…, A n, C n,TC) where C i =C ∀ A i ∈ X, C i left unchanged for A i ∉ X Application to ER: - SiC(Is Assigned to,{Function},S) - assigns property Function of relationship “Is Assigned to” to a classification of secret.

SSN Name Dep Salary Title Function SSN Date Client Subject EmployeeProject Is Assigned to (0,N)(0,M) ER Diagram – classifying properties of security objects

Object Classification Constraints – Content-based Constraints Let A i be an attribute of security object O with domain D i, let P be a predicate defined on A i and let X ⊆ {A i,…,A n } CbC (O(X), P: A i θ a) = C or CbC (O(X), P: A i θ A j ) = C (θ ∈ {=,≠,,≤,≥}, a ∈ D i, i ≠ j, C ∈ SL) For any instance o of security object O(A 1,…,A n ) for which a predicate evaluates into true the transformation into o(a 1,c 1,…,a n,c n,tc) is performed Classifications are assigned in a way that c i = C in the case A i ∈ X, c i left unchanged otherwise Application to ER: - CbC (Employee, {SSN, Name}, Salary, ‘≥’, ‘100’, Co)) - represents the semantic that properties SSN and Name of employees with a salary ≥ 100 are treated as confidential information

SSN Name Dep Salary Title Function SSN Date Client Subject EmployeeProject Is Assigned to P (0,N)(0,M) ER Diagram – classifying properties of security objects

Object Classification Constraints – Complex Constraints Let O, O ’ be two security objects and the existence of an instance o of O is dependent on the existence of a corresponding occurrence o ’ of O ’ where the k values of the identifying property K’ of o’ are identical to k values of attributes of o (foreign key) Let P(O ’ ) be a valid predicate defined on o’ and let X ⊆ {A 1,…,A n } be an attribute set of O CoC (O(X), P(O ’ )) = C (C ∈ SL) For every instance o of security object O(A 1,…,A n ) for which a predicate evaluates into true in the related object o’ of O ’ the transformation into o(a 1,c 1,…,a n,c n,tc) is performed Classifications are assigned in a way that c i = C in the case A i ∈ X, c i left unchanged otherwise

Object Classification Constraints – Complex Constraints (con’t) Application to ER: - CoC (Is Assigned to, {SSN}, Project, Subject, ‘=‘, ‘Research’, S) - individual assignment data (SSN) is regarded as secret information in the case the assignment refers to a project with Subject = ‘Research’

SSN Name Dep Salary Title Function SSN Date Client Subject EmployeeProject Is Assigned to P P (0,N)(0,M) ER Diagram – classifying properties of security objects

Object Classification Constraints – Level-based Constraints Let level (A i ) be a function that returns the classification c i of the value of attribute Ai in object o(a 1,c 1,…,a n,c n,tc) of a multilevel security object O m Let X be a set of attributes of O m such that X ⊆ {A 1,…,A n } LbC (O(X)) = level (A i ) Result for every object o(a 1,c 1,…,a n,c n,tc) to the assignment c j = c i in the case A j ∈ X Application to ER: - LbC (Project, {Client}, Subject) - states that property Client of security object Project must always have the same classification as the property Subject of the Project

SSN Name Dep Salary Title Function SSN Date Client Subject EmployeeProject Is Assigned to P P (0,N)(0,M) ER Diagram – classifying properties of security objects

Query Result Classification Constraints – Association-based Constraints Let O (A 1,…A n ) be a security object with identifying property K Let X (X ⊆ {A 1,…,A n } (K ⋂ X = {}) be a set of attributes of O AbC (O (K,X)) = C (C ∈ SL) Results in the assignment of security level C to the retrieval result of each query that takes X together with identifying property K Application to ER: - AbC (Employee, {Salary}, Co) - the salary of an individual person is confidential - the value of salaries without the information which employee gets what salary is unclassified

SSN Name Dep Salary Title Function SSN Date Client Subject EmployeeProject Is Assigned to (0,N)(0,M) ER Diagram – classifying query results [Co]

Query Result Classification Constraints – Aggregation Constraints Let count(O) be a function that returns the number of instances referenced by a particular query and belonging to security object O (A 1,…,A n ) Let X (X ⊆ {A 1,…,A n }) be sensitive attributes of O AgC (O, (X, count(O) > n = C (C ∈ SL, n ∈ N) Result into the classification C for the retrieval result of a query in the case count(O) > n, i.e. the number of instances of O referenced by a query accessing properties X exceeds the value n

Query Result Classification Constraints – Aggregation Constraints (con’t) Application to ER: - AgC (Is Assigned to, {Title}, ‘3’, S) - the information which employee is assigned to what projects is regarded as unclassified - aggregating all assignments for a certain project and thereby inferring which team is responsible for what project is considered secret

SSN Name Dep Salary Title Function SSN Date Client Subject EmployeeProject Is Assigned to (0,N)(0,M) ER Diagram – classifying query results [Co] 3

Query Result Classification Constraints – Inference Constraints Let PO be the set of multilevel objects involved in a potential logical inference Let O, O ’ be two particular objects from PO with corresponding multilevel representation O (A 1,C 1,…,A n,C n,TC) and O ’ (A ’ 1,C ’ 1,…,A ’ n,C ’ n,TC ’ ) Let X ⊆ {A 1,…,A n } and Y ⊆ {A ’ 1,…,A ’ n }) IfC (O(X), O ’ (Y)) = C Results into the assignment of security level C to the retrieval result of each query that takes Y together with the properties in X

Query Result Classification Constraints – Inference Constraints (con’t) Application to ER: - IfC (Employee, {Dep}, Project, {Subject}, Co) - consider the situation where the information which employee is assigned to what projects is considered as confidential - from having access to the department an employee works for and to the subject of a project, users may infer which department may be responsible for the project and thus may conclude which employee are involved

SSN Name Dep Salary Title Function SSN Date Client Subject EmployeeProject Is Assigned to (0,N)(0,M) ER Diagram – classifying query results X [Co] 3

QUESTION?