Security_BG-1

CSE4701

Chapters 23 6e - 22 5e: Security

Prof. Steven A. Demurjian, Sr. Computer Science & Engineering Department

The University of Connecticut371 Fairfield Road, Box U-1155

Storrs, CT 06269-1155steve@engr.uconn.edu

http://www.engr.uconn.edu/~steve(860) 486 - 4818

The majority of these slides represent material that has been accumulated from various sources over the years.

A portion these slides are being used with the permission of Dr. Ling Lui, Associate Professor, College of Computing, Georgia Tech.

Security_BG-2

CSE4701

Overview Objective: Cover the wide range of Background

Concepts and Security Ideas Motivation: Importance, Concepts, and Issues Glossary of Security Terms Security Policy, Authentication, and Authorization Security in Java Access Control

Mandatory Access Control (MAC) Discretionary Access Control (DAC) Role-Based Access Control (RBAC)

DB Security, Cryptography, Security in Statistical DB Middleware Security Web Based Security Concluding Remarks

Security_BG-3

CSE4701

Motivation: General Concepts Authentication

Proving you are who you are Signing a Message Is Client who s/he Says they are?

Authorization Granting/Denying Access Revoking Access Does Client have Permission to do what s/he

Wants? Encryption

Establishing Communications Such that No One but Receiver will Get the Content of the Message

Symmetric Encryption and Public Key Encryption

Security_BG-4

CSE4701

Motivation: Type of Security Issues Legal and Ethical Issues

Information that Must be Protected Information that Must be Accessible HIPPA vs. Emergent Health Situations

Policy Issues Who Can See What Information When? Applications Limits w.r.t. Data vs. Users?

System Level Enforcement What is Provided by the DBMS? Programming

Language? OS? Application? Web Server? Client? How Do All of the Pieces Interact?

Multiple Security Levels/Organizational Enforcement Mapping Security to Organizational Hierarchy Protecting Information in Organization

Security_BG-5

CSE4701

Glossary of Protection and Security Terms Principal

Entity (Person/Process/etc.) to Which Authorizations are Granted

Can be a User, User Group, Program, Client, etc. Also Known as Subject

Protected Object Known Object whose Internal Structure is

Inaccessible Except by Protection System The Unit of Protection For Our Purposes:

Table, Column, Tuple Data and Meta-Data

Glossary from: Saltzer and Schroeder, “The Protection of Information in Computer Systems”, Proc. of IEEE, Vol. 63, No. 9, September 1975.

Security_BG-6

CSE4701

Glossary of Protection and Security Terms Access Control List

List of Principals (User, User Group, Process, …) Authorized to have Access to Some Object

For Every Object, Maintain Authorized Principals Easily Implemented in Algorithm/Typically in OS

Authenticate Verify Identity of Principal Making Request In OS - Equivalent to Logging on (ID, Password) May be More Complicated Based on Security

Needs Authorize

Grant Principal Access to Objects Granularity Ranges from Fine to Coarse Application Directed

Security_BG-7

CSE4701

Glossary of Protection and Security Terms Capability

Unforgeable Ticket as Proof of Authorization of Presenter (Principal) to Access Named Object

Ticket or Certificate Must be Presented at Each Access

Capability List List of Protected Objects which Likewise List

Authorized Principles Used in Conjunction with Tickets for

Authorization Certify

Verify Accuracy, Correctness, & Completeness of Security/Protection Mechanism

Critical for Select Domains (DoD, Banking, etc.)

Security_BG-8

CSE4701

Glossary of Protection and Security Terms Confinement

Restricting What a Process Can Do to with Authorized Objects

Similar in Concept to Sandbox of Java Domain

Objects Currently Accessed by Principal (De)Encryption

De(Encoding) of Data According to Transformation Key for Transmission/Storage

Reciprocal Activity - Many Different Options Grant

Authorize Access to Objects by Principals Who Can do What When

Security_BG-9

CSE4701

Glossary of Protection and Security Terms Password

Encrypted Character String to Authenticate Identity of Individual

Critical to Encrypt Also from Client to Login Server Client Types in Plain Text that is Encrypted Encrypted login Travels of Network Decrypted at Login Server and Verified

Permission Form of Allowed Access to Object (R, W, RW) Level of Access is System Dependent Unix File System has:

r, w, x for User, Group, and Other

Security_BG-10

CSE4701

Glossary of Protection and Security Terms Privacy

Ability to Decide Whether, When, and to Whom Information is Released

Is Anyone Intercepting Client/Server Communications?

Propagation Principal Passing on Authorization to Object to

Another Principal Current Term Today is “Delegation” Principal Must be Authorized to Delegate

Privileges to Another Principal Enforcement Mechanism

Centralized and Distributed “Code” Enforces Security Policy at Runtime

Security_BG-11

CSE4701

Glossary of Protection and Security Terms Protection & Security

Mechanisms and Techniques to Control Access to Information by Executing Programs

Enforcement Mechanism, Cryptography Algorithms, Database Security, etc.

Revoke Remove Previously Authorized Access from

Principals Security Tools Must Promote Grant, Revoke, and

Authorize in a Dynamic Setting Ticket-Oriented

Each Principal Maintains List of Unforgeable Tickets Denoting Objects have been Authorized

Works with Capability Lists

Security_BG-12

CSE4701

DB Security Approach Software Engineers can Write Complex Programs

Limited by Intellectual Capabilities DB Designer Must Create Protection Scheme that

Can’t be Bypassed by Current and Future Software Users and DB Initiators

Users have Dedicated and Shared DB Items DB Items Shared by User Groups vs. DB Items

Globally Shared Users Spawn Clients that Access DB Items Clients May be Local or Remote (on Another

Machine Connected via Network) Protection System of DB Must Support Above

According to Organization’s Admin. Policy

Security_BG-13

CSE4701

Policy & Mechanism Security Policy Defines Rules for Authorizing Access

to Computer and Resources Who are Users? What are DB Items? What DB

Items are Available to Each User? Etc… For PHR – Patient Defines Policy

Protection Mechanisms Authenticate Access to DB Items, File and Memory Protection What is the Granularity of Access?

A Security Policy is an Organizations Strategy to Authorize Access to the DBMS DB Items Each Policy is Application Dependent Range from Full to Limited Access

Security Transcends DB as a Separate Research and Realization for All Types of Systems/Applications

Security_BG-14

CSE4701

Authentication User/Process Authentication

Is this User/Client Who It Claims to Be? Passwords More Sophisticated Mechanisms Need for Re-authentication

Authentication in Networks Is this Computer Who It Claims to Be?

File Downloading and Transferring Obtaining Network Services What is Java Promise? What Does Java Guarantee re.

Applets? What can Application do that Applet Can’t? DB Authentication

Uncontrolled Access (Select, Modify, etc.) Can be Limited (Authorized) requiring Authentication

Security_BG-15

CSE4701

Authorization Ability of Principals to Use Machines, Objects,

Resources, etc. Security Policy Defines Capabilities of Each Principal

Against Objects, Resources, etc. Authorization Mechanism Enforces Policy at Runtime External Authorization

User Attempts to Access Computer Authenticate Identify and Verify Authorizations

Internal Authorization Can Process Access a Specific Resource?

Database Authorization What Can Each User Do Against the DB? Select,

Insert, Update, Delete? Are Users Limited to Subsets of Tuples by Value?

Security_BG-16

CSE4701

User Authentication Combination of User ID and Password Universal for

Access to Computers However, Cannot Prevent …

Guessing of Passwords Stolen and Decrypted Passwords Masquerading of Intended User

Is User Who they are Supposed to be? What Extra Information Can User be Asked to Supply? What About Life Critical Situations – EMR’s Treating

Accident Victim? Past Invasion of Engineering Computing

yppasswd File Stolen/Decrypted S. Demurjian’s Sun Workstation Corrupted

Security_BG-17

CSE4701

Network Authentication Computers Must Interact with One Another

Classic Example, Transmitting E-Mail Msgs. Does Transferring Computer have Right to Store a

File on Another Computer? What About PHR Data Routed from Web to

Application to DB to EMR? Where is the Control? https? Encryption? Guarantee Unencrypted Data not Stored on the Way?

Viruses: Passive Penetrating Entity Software Module Hidden in Another Module When Container Executed, Virus Can Penetrate

and Wreak Havoc Worms: Active Penetrating Entity

Actively Seeks to Invade Machine

Security_BG-18

CSE4701

Core Security Capabilities of Java Sandbox and Applet Level Security

Downloaded Applets are Confined in a Targeted Portion of System During Execution

Execution of Untrusted Code in Trusted Way What is Sandbox?

Area of Web-Browser Dedicated to Applet Applet Limited to Sandbox to Prohibit Access to

Local Machine/Environment Utilizes Class Loader, Bytecode Verifier, and

Security Manager Three Components Maintain System Integrity How Does this Occur?

Why is this Relevant for BMI Applications? Pervasive Usage of Applets and Client Java Code

Security_BG-19

CSE4701

Core Security Capabilities of Java Class Loader - Only Load Correct Classes Bytecode Verifier - Classes in Correct Format

Both Don’t care Where the Code is from (compiled from Java or another PL – just is it correct)

Security Manager - Untrusted Classes Can’t Execute Dangerous Instructions nor Access Protected System Resources

Role of Security Managers Enforces Boundaries of Sandbox All Java Classes ask Manager for Permission to

Perform Certain Operations Implements/Imposes Appl. Security Policy Java Interface Class Implementable by Users Integrated with Exception Handling of Java

Security_BG-20

CSE4701

Recall Java Bytecode Verification:

Security_BG-21

CSE4701

Digital Signatures and JAR Files When Can Applets Become Applications?

Trusted Publisher (Originator of Applet) Signed Applet is Authenticated Java Security Manager May Allow Applet out of

Sandbox to be Application How is Information Transmitted and Exchanged?

JAR: Archived (Compressed) Files Bundling of Code/Data into Java Archive Associated Digital Signature for Verification Transmission via Object Serialization

Again, for BMI Web Applications to PCs, PDAs, and Cells Pervasiveness of Technology and Potential for

Misuse and Information Release

Security_BG-22

CSE4701

Available Access Control Approaches Mandatory Access Control (MAC)

Bell/Lapadula Security Model Security Classification Levels for Data Items Access Based on Security Clearance of User

Role Based Access Control (RBAC) Govern Access to Information based on Role Users can Play Different Roles at Different Times

Responsibilities of Users Guiding Factor Facilitate User Interactions while Simultaneously

Protecting Sensitive Data Discretionary Access Control (DAC)

Richer Set of Access Modes - Govern Access to Information based on User Id

Discretionary Rules on Access Privileges Focused on Application Needs/Requirements

Security_BG-23

CSE4701

What are Key Access Control Concepts? Assurance

Are the Security Privileges for Each User Adequate to Support their Activities?

Do the Security Privileges for Each User Meet but Not Exceed their Capabilities?

Consistency Are the Defined Security Privileges for Each User

Internally Consistent? Least-Privilege Principle: Just Enough Access

Are the Defined Security Privileges for Related Users Globally Consistent? Mutual-Exclusion: Read for Some-Write for Others

Security_BG-24

CSE4701

Mandatory Access Control Bell-Lapadula Model [1976]

An Extension of the Access Matrix Model The Model is Based on Subject-Object Paradigm

Subjects: Active Elements Objects: Passive Elements

Four Access Modes/Categories Executable by Subjects on Objects Read-only or Read Append (Write without Read) Execute (Executes an Object/program) Read-Write or Write

Security_BG-25

CSE4701

Mandatory Security Mechanism Typical Security Classification Levels for

Subjects/programs and Objects/resources Top Secret (TS) and Secret (S) Confidential (C) and Unclassified (U)

Rules: TS is the Highest and U is the Lowest Level TS > S > C > U Security Levels:

C1 is Security Clearance Given to User U1 C2 is Security Classification Given to Object O1 U1 can Access O1 iff C1 C2 This is Referred to as the Domination of U1 Over O1

Security_BG-26

CSE4701

Operations Get access

Initiate access to object in the given mode Release access

Terminate access previously started by get Given access

grant an access mode on an object to a subject Rescind access

Revoke access previously granted with the “give” operation Create object

An object may be inactive or active; this takes an inactive object and adds to the object hierarchy

Delete object Deactivates an active object

Change subject security level Change object security level

Security_BG-27

CSE4701

Mandatory Security Mechanism Restriction (Axiom 1):

No Subject S Can Read an Object O if the Object’s Security Classification is Higher Than the Subject’s Security Clearance S Can Read O iff Clearance(S) Classification(O)

No Subject May Write an Object that has Lower Security Class than the Subject’s Security Clearance S Can Write O iff Clearance(S) Classification(O) This Prevents Information Flow from Higher

Classification to Lower Classification Levels Depending on the Desired MAC, Different Axioms

Can be Employed that Satisfy Different Criteria ofClearance Dominating Classification

Security_BG-28

CSE4701

Other Axioms Simple Security (SS) Property

Subject S may have Read(Write) Access to Object O iff Clearance of S Dominates the Classification of O

Star (*) Property A Subject Can Only Read Objects at or Above

their Level A Subject Can Only Write Objects at or Below

their Level Tranquility Principle

No Subject Can Modify Classification of Active Object

Security_BG-29

CSE4701

Mandatory Security Mechanism There are Numerous Security Properties Regarding the

Ability of a Subject S to Read (Write) an Object O These Properties Control the flow of Information from

Users to the Objects that they are allowed to Access Simple Security Property (Read Down – No Read Up)

No Subject S Can Read an Object O if the Object’s Security Classification is Higher Than the Subject’s Security Clearance

S Can Read O iff Clearance(S) Classification(O) This Insures that a Subject S cannot Read

Information Above his/her Security Level

TS S C U

User (S) Read Down

Security_BG-30

CSE4701

Mandatory Security Mechanism Simple Integrity Property (Write Down–No Write Up)

A Subject May Write an Object only if that Object is at or Below the Subject’s Security Clearance

S Can Write O iff Clearance(S) ≥ Classification(O) This Allows the Potential of Information Flow

from Higher Classification to Lower Classification Levels

This Prevents the Ability of a Subject S to Corrupt Data above its Security Level

Security Designer Must Choose their Poison!

TS S C U

User (S) Write Down

Security_BG-31

CSE4701

Mandatory Security Mechanism Liberal * Property (Write Up–No Write Down)

No Subject May Write an Object that has Lower Security Class than the Subject’s Security Clearance

S Can Write O iff Clearance(S) Classification(O) This Prevents Information Flow from Higher

Classification to Lower Classification Levels Such an Attempt can be Overt or Unintentional

Likewise, this Allows a Subject to Corrupt Information above its Level

TS S C U

User (S)Write Up

Security_BG-32

CSE4701

Mandatory Security Mechanism Strict * Property (Read/Write Equal)

A Subject May Only Read/Write an Object that has the Exact Same Security Class than the Subject’s Security Clearance

S Can Read/Write O iff Clearance(S) = Classification(O)

This Limits Information Flow to within a Level

TS S C U

User (S)

Read EqualWrite Equal

Security_BG-33

CSE4701

Using the Properties Security Policy is Typically a Combination of one

Read and one Write Property Simple Security + Simple Integrity Simple Security + Strict * (Write) Simple Security + Liberal * Strict * (Read) + Simple Integrity Strict * (Read) + Strict * (Write) Strict * (Read) + Liberal *

Objective: Security Engineer Must Choose the Most Appropriate Combination for their Application

Security_BG-34

CSE4701

A Classic Example Simple Security for Reads

See Information at User Clearance Level and Lower (Less Secure)

No Chance of Viewing TS Information Liberal * for Writes

Write Information at User Clearance Level and Above (More Secure)

No Chance of Releasing “S” Data to Lower Levels

TS S C U

User (S)

Write Up

Read Down

Security_BG-35

CSE4701

Other Axioms Discretionary Property (DS-property)

Every Current Access Must Be Present in the Access Matrix

For All Subjects S, Objects O, and the Access Mode M:

<S,o,m> B M M[s,o] Non-Accessibility of Inactive Objects

A Subject Cannot Read the Contents of an Inactive Object

Rewriting of Inactive Objects A Newly Activated Object is Assigned to an Initial

State Independent of the Previous Activation of the Object

Security_BG-36

CSE4701

Illustrating MAC Consider the EMPLOYEE Table Below with Two

Instances Notice Classifications on Each Tuple (TC) Notice Classifications on Each Attribute Value

Interpretation: Limit Who Can See Each Tuple and Values Focus on User Clearance w.r.t. Classifications

Security_BG-37

CSE4701

Illustrating MAC Whenever a User Attempts to Access a Table, the

Table is Filtered According to U’s Clearance First Set are for a User at Confidential Level Second Set is For a User at Unclassified Level

Security_BG-38

CSE4701

Security in Software Applications Extensive Published Research (Demurjian, et al) in

Last Ten Years for DAC/RBAC for OO Efforts in

Automatically Generatable and Reusable Enforcement Mechanisms

MAC/DAC/RBAC within Distributed Setting Premise:

Customizable Public Interface of Class Access to Public Interface is Variable and Based on

User Needs and Responsibilities Only Give Exactly What’s Needed and No More

Please see:www.engr.uconn.edu/~steve/DSEC/desc.html

Security_BG-39

CSE4701

What is Role Based Access Control (RBAC)?

Most OO Programming and Database Languages have a Single Public Interface that is Shared by All Users of OT/Class

Consequently, Public Interface Often Union of all Possible Methods Required by All Likely Users

Discretionary Access Control: Occurs at Type-Level Different Portions of Public Interface Available to

Different Users at Different Times Depending on User-Roles

Promote Potential Public Interface

Security_BG-40

CSE4701

Motivating Security for OO Paradigm OO Paradigm Provides Minimal Support via Public

Interface and Private Implementation Public Interface Represents UNION of all Possible

Privileges Needed by All Potential Users A Method in the Public Interface for One Specific

User Available to ALL Users Can Access to Public Interface be Customized? Can Individuals have Particular Access to Specific

Subsets of Public Interface? Can Access be Based on (Potentially) Dynamic

User Roles? Can Code be Automatically Generated to

Implement an Enforcement Mechanism? Role of OO Paradigm in Support a Generic,

Evolvable, Reusable Enforcement Mechanism?

Security_BG-41

CSE4701

Why is RBAC Needed? In Health Care, different professionals (e.g., Nurses

vs. Physicians vs. Administrators, etc.) Require Select Access to Sensitive Patient Data

Suppose we have a Patient Access Client Lois playing the Nurse Role would be Allowed to

Enter Patient History, Record Vital Signs, etc. Steve playing M.D. Role would be Allowed to do

all of a Nurse plus Write Orders, Enter Scripts, etc. Vicky playing Admin Role would be Allowed to

Enter Demographic/Insurance Info. Role Dictates Client Behavior

Security_BG-42

CSE4701

Why is RBAC Needed? Many Situations When Application Library Designer

(SWE) Could Utilize More Fine-Grained Control to Access of Public Interface

Tradeoff Between Developers and End-Users SWEs Have Different Roles Based on Their

Responsibilities Related to Cooperative Design on an Application

SWEs Should Only See Those Portions of the Application That They Need to See or That They Will Be Responsible for Implementing

End-users Must Be Limited in Their Interactions and Access Depending on Their Roles

Security_BG-43

CSE4701

Examples of Why RBAC is Needed In HTSS, the public interface for Items has methods

that read (for Scanner, I-Controller) and modify instances (only for I-Controller) Read Methods Targeted for Certain System

Functions (e.g., Scan Item) Update Methods Targeted for Others (e.g., as Item

is Scanned, Decrement Inventory Amount) In HCA, different health care professionals (e.g.,

Nurses vs. Physicians vs. Administrators, etc.) require select access to sensitive patient data Physician’s Write Scripts Nurses Enter Patient Data (Vitals + History) All Access Shared Medical Record Access is Limited Based on Role

Security_BG-44

CSE4701

public class PatientRecord { private: Data/Methods as Needed; public: write_medical_history(); write_prescription(); get_medical_history(); get_diagnosis(); set_payment_mode(); etc…

For MDsand Nurses

For MDs Only

For Admitting

RBAC for OO Public Interface is Union of All Privileges for All

Potential Users No Explicit way to Prohibit Access Customizable Public Interface of Class Access to Public Interface is Variable and Based on

User Needs and Responsibilities Only Give Exactly What’s Needed and No More

Security_BG-45

CSE4701

Sample RBAC Hierarchy for HCA

Users

Medical_Staff

Nurse Physcian

UR:Manager

UR:Staff_RN UR:Education

UR:Discharge_Plng

UR:Private UR:Attending

Support_Staff

Etc.

Technician

UR:Director

UR:Lab UR:Pharmacy

UR:Radiology

Security_BG-46

CSE4701

Sample RBAC Hierarchy for University

Users / \ +---+ +-----+ / \ non-academic-staff academic-staff / \ \ / \ \.... / \ \ / \ purchasing campus-police ... dept-staff registrar-staff ... / \ ... ... / \ grade-recording transcript-issuing

Security_BG-47

CSE4701

Sample RBAC Hierarchy for Portal

Users

Medical_Staff

Clinical Researcher Basic User

UR: Poster

UR: ForumLeader

UR: DataAnalyst UR: EdMaterials

UR: etc…

Patients

Etc.

Provider

UR: BasicPHR

UR: Nurse UR: OccTher

UR: Physician

Security_BG-48

CSE4701

NIST RBAC Standard http://csrc.nist.gov/groups/SNS/rbac/ Formalized in 1992 (Ferraiolo and Kuhn) Based on Work by Sandhu, et al. Lot’s of Health Care Related Case Studies:

http://csrc.nist.gov/groups/SNS/rbac/case_studies.html Please Visit the Site … May be Applicable Applications ….

Briefly, Let’s Review …

Security_BG-49

CSE4701

RBAC Model Variants http://csrc.nist.gov/groups/SNS/rbac/documents/towards-

std.pdf Transition from Essential Features to Complex Model

Security_BG-50

CSE4701

Level 1 and Level 2 Level 1: Three States and UA/PA Level 2: Add in Role Hierarchy Look on R State

Security_BG-51

CSE4701

Example Role Hierarchies

Security_BG-52

CSE4701

Constrained RBAC – with SOD

Security_BG-53

CSE4701

Constrained RBAC – with SOD

Security_BG-54

CSE4701

Discretionary Access Control Discretionary

Grant Privileges to Users, Including the Capabilities to Access Specific Data Items in a Specific Mode

Available in Most Commercial DBMSs Aspects of DAC

User’s Identity Predefined Discretionary “Rules” Defined by the

Security Administrator Focus on Two Variants of this Model

Access Matrix Model Lampson’s Protection System

Role Delegation and Delegation Authority Detail DAC in SQL2

Security_BG-55

CSE4701

What is Role Delegation? Role Delegation, a User-to-User Relationship, Allows

an Original User (OU) to Transfer Responsibility for a Particular Role to a Delegated User (DU)

Two Major Types of Delegation Administratively-directed Delegation has an

Administrative Infrastructure Outside the Direct Control of a User Mediates Delegation

User-directed Delegation has an User (Playing a Role) Determining If and When to Delegate a Role to Another User

In Both, Security Administrators Still Oversee Who Can Do What When w.r.t. Delegation

Delegation Vital in Health Care: Provider on-Call, Emergent Situations, DCP …

Security_BG-56

CSE4701

Why is Role Delegation Important? Many Different Scenarios Under Which Privileges

May Want to be Passed to Other Individuals Large organizations often require delegation to

meet demands on individuals in specific roles for certain periods of time

True in Many Different Sectors Health Care Financial Services Engineering Academic Setting

Key Issues: Who Controls Delegation to Whom? How are Delegation Requirements Enforced?

Security_BG-57

CSE4701

What Can be Delegated? Authority to Do the Task, Carries the Least

Responsibility Necessary to Execute the Task, but Does Mean the Delegated User Can Execute the Delegated Task or Role.

Responsibility to Do a Task Implies Accountability and a Vested Interest that a Task or Role Can Be Executed Properly.

Duty to Perform a Task Implies that the Delegated User is Obligated to Execute the Given Task.

Our Focus: Delegate Authority Only

Security_BG-58

CSE4701

Delegation/Pass on Delegation Authorities When Establishing Privileges (by the Security Officer)

there must be the Ability to Define: Delegation Authority (DA)

Recall:Security Officer can Delegate a Role to User DA Means that the Security Officer Can Delegate the

Authority to Delegate to another User Role Can be Delegated by one User to Another However, Delegation Authority Cannot

Pass-on Delegation Authority (PODA) PODA Augments DA to Allow the Delegation Authority

to Also be Delegated as Part of the Delegation of a Role to a User

Security_BG-59

CSE4701

Example - Role Delegation General DoBest Delegates his Role CDR_CR1

(Commander, Crisis 1) to Colonel DoGood with DA, where DoBest, CDR_CR1, and DoGood defined as:

OU: [DoBest, [ct, ], T]UR: [CDR_CR1, [01dec00, 01dec01], T]UA: [DoBest, CDR_CR1, [01dec00, 01dec01]]DA: YesPODA: Yes

After Delegation:

DU: [DoGood, [01dec00, 01jun01], T]UA: [DoGood, CDR_CR1, [01dec00, 01jun01]]

Security_BG-60

CSE4701

Example - Role Delegation Now, Colonel DoGood wishes to re-delegate

CDR_CR1 to Major CanDoRight, which can be defined as:

DU: [DoGood, [01dec00, 01jun01], T]UR: [CDR_CR1, [01dec00, 01dec01], T]UA: [DoGood, CDR_CR1, [01dec00, 01jun01]]DA: YesPODA: No

After Delegation:

DU: [CanDoRight, [01jan01, 01feb01], T]UA: [CanDoRight, CDR_CR1, [01dec00, 01jun01]]

Security_BG-61

CSE4701

Role Delegation Revocation Rules User-to-User Delegation Authority Rule

A User (OU or DU) Who is a Current Member of a Delegatable Role (DUR), Can Delegate that User Role to Any User that Meets the Prerequisite Conditions of the Role: DU Receiving the Role is Not a Member of the Role; OU or DU is Identified As Having Delegation Authority

for the Role; DU Meets the Mandatory Access Control Constraints

(MACC).

Security_BG-62

CSE4701

Role Delegation Revocation Rules Delegation Revocation Authorization Rule:

An Original User Can Revoke Any Delegated User From a User Role in Which the OU Executed the Delegation.

This is a Stricter Interpretation than [Zhan01], Which Allows Any OU of a Role Revocation Authority Over a DU in the Delegation Path.

In Addition, a Security Administrator Can Revoke Any Delegation.

Cascading Revocation Rule: Whenever an OU or DU in the delegation path is

revoked, all DUs in the path are revoked.

Security_BG-63

CSE4701

Monotonicity and Permanence Definition: Monotonicity Refers to the State of

Control the OU Possesses After Role Delegation Monotonic Delegation Means That the OU

Maintains Control of the Delegated Role Non-monotonic Means That the OU Passes the

Control of the Role to DU Definition: Permanence Refers to Delegation in

Terms of Time Duration Permanent Delegation is When a DU Permanently

Replaces the OU Temporary Delegation Has an Associated Time

Limit With Each Role

Security_BG-64

CSE4701

Totality and Administration Definition: Totality Refers to How Completely the

Permissions Assigned to the Role Are Delegated Partial Delegation Refers to the Delegation of a

Subset of the Permissions of the Role Total Delegation Refers to the Situation All of the

Permissions of the Role Are Delegated Definition: Administration Refers to how Delegation

will be Administered User Directed is when the User Controls all

Aspects of Delegation Administrator-Directed (Third party, Agent-

directed) is when Control is with the Security Officer

Security_BG-65

CSE4701

Revocation Definition: Cascading Revocation Refers to the

Indirect Revocation of All DUs When the OU Revokes Delegation or Administration Revokes the OU’s Delegated Role

Definition: Grant-Dependency Revocation Refers to Who Has Authority to Revoke a DU Grant-Dependent Revocation Only Allow the OU

to Revoke the Delegated Role Grant-Independent Revocation Allows Any

Original Member of the DUR to Revoke a Delegated Role

Security_BG-66

CSE4701

Database Security Approach Software Engineers can Write Complex Programs

Limited by Intellectual Capabilities DB Designer Must Create Protection Scheme that

Can’t be Bypassed by Current and Future Software Users and DB Initiators

Users have Dedicated and Shared DB Items DB Items Shared by User Groups vs. DB Items

Globally Shared Users Spawn Clients that Access DB Items Clients May be Local or Remote (on Another

Machine Connected via Network) Protection System of DB Must Support Above

According to Organization’s Admin. Policy

Security_BG-67

CSE4701

Database Security Types of Security

Database Security is Mainly Related with Access Rights to the Database

Database Security Involves Issues Such as Governmental or Corporate Level of Policies Privacy and Confidentiality Requirements

For Example - Consider a Medicine Prescription Physician or PA Only One Authorized to Write Drug,

Dosage, Refills, Generic vs. Brand, etc. Pharmacist by Law Can Enter Script, Replace Brand

with Generic, Alter “Refills” - Can’t Change the Med By Law - Protect the Script per Patient (MD/Insurance)

Access Control is Mechanism to Prevent Unauthorized Access to Databases

Security_BG-68

CSE4701

Database Security Database Administrator (DBA) has the Privileged

Commands to Perform the Following on Databases Account Creation Privilege Granting Privilege Revocation Security Level Assignments

Elements of the Security Model Subjects (Principals) Objects (Data) Access Methods (How to Use) Policies (Application Dictated) Authorizations (Who Can Do What) Authentication and Enforcement (Runtime)

Security_BG-69

CSE4701

Available Security Approaches Mandatory Access Control (MAC)

Bell/Lapadula Security Model Security Classification Levels for Data Items Access Based on Security Clearance of User

Discretionary Access Control (DAC) Richer Set of Access Modes - Govern Access to

Information based on User Id Discretionary Rules on Access Privileges Focused on Application Needs/Requirements

User-Role Based Security (URBS) Govern Access to Information based on Role Users can Play Different Roles at Different Times

Responsibilities of Users Guiding Factor Facilitate User Interactions while Simultaneously

Protecting Sensitive Data

Security_BG-70

CSE4701

Discretionary Access Control Discretionary

Grant Privileges to Users, Including the Capabilities to Access Specific Data Items in a Specific Mode

Available in Most Commercial DBMSs Aspects of DAC

User’s Identity Predefined Discretionary “Rules” Defined by the

Security Administrator Focus on Two Variants of this Model

Access Matrix Model Lampson’s Protection System

Detail DAC in SQL2

Security_BG-71

CSE4701

Access Matrix Model Proposed by Harrison, Ruzzo, and Ullman, 1976 Basic Concepts are

S: Set of Subjects (Principals) O: Set of Objects (Data Items) A: The Access Matrix (Who can do What)

Rows Correspond to the Subjects Columns Correspond to the Objects

We’ll see a Variant of this in Lampson

Security_BG-72

CSE4701

Access Matrix Model Conditions Associated with Access Authorization

Data-Dependent Specifying Constraints on the Value of Accessed Data

Time-Dependent Specifying Constraints on the Time When an Access

can Take Place Context-Dependent

Specifying Constraints on Combinations of Data Which can be Accessed

History-Dependent: Specifying Constraints Dependent on Previously

Performed Accesses

Security_BG-73

CSE4701

O1 …. Oi …. Omobject

subject

S1S2….

Sn

A[S1,O1] A[S1,Oi] A[S1,Om]

A[S2,O1] A[S2,Oi] A[S2,Om]

A[Sn,O1] A[Sn,Oi] A[Sn,Om]

Access Matrix Model An Example

Object Types: Relations, Views, Rows (records), Columns,

Operations Subject Types:

Users, Accounts, Programs

Security_BG-74

CSE4701

Access Modes Access Modes

Read, Write, Append, and Execute Authorization

A[S,O] is an Entry in the Access Matrix A[S,O] can be Authorized to One or More

Operations Mechanisms

<create> <subject Si > - Add a Row create> <object Oj> - Add a Column <destroy> <subject Si > - Remove a Row <destroy> <object Oj> - Remove a Column <enter> <operation x into A[Si, Oj] <delete> <operation x from A[Si, Oj]

Security_BG-75

CSE4701

DAC in SQL2 SQL2 Uses the Concept of Authorization Identifier

User Group (could be Single User) References a Set of User Accounts

DBA Must Provide Selective Access by each User to Every Relation in the DB Based on Account

Two Levels of Privilege Assignment Account Level - DBA Manages the Accounts for to

Authorize Users to Different DBs Relation/Table Level - Controlling Access to Each

Relation or View in a DB Objective

Manage and Administer Design/Realize the Security Policy

Security_BG-76

CSE4701

Privileges in SQL Allocated at a Relation Level

SELECT Privilege - Gives Account Retrieval Access

MODIFY Privilege Gives Account Ability to Change the Database Subdivided into Insert, Update, and Delete Insert and Update can be Specialized on Different

Attributes of Relation REFERENCES Privilege

Gives Account the Ability re. Integrity Constraints Can be Restricted to Certain Attributes of Relation

Commands to both GRANT and REVOKE are Supported

Security_BG-77

CSE4701

Example Schema Consider Two Database Tables:

EMPLOYEE (NAME, SNN, BDATE, ADDRESS, SET, SALARY,

DNO) DEPARTMENT

(D#, DNAME, MGRSNN) Consider Four Accounts/Users:

U1, U2, U3 and U4 Limit U1 to be Able to Create Schema In SQL

GRANT CREATETAB TO U1; In SQL2

CREATE SCHEMA EXAMPLE AUTHORIZATION U1; U1 Can Create Tables In Schema EXAMPLE

Security_BG-78

CSE4701

SQL Examples Suppose U1 Wants to Grant U2 the Ability to Insert

and Delete into EMPLOYEE and DEPARTMENT U1 Wants to Disallow Ability of U2 to Propagate

(Delegate) Insert/Delete to Other Users GRANT INSERT, DELETE ON EMPLOYEE,

DEPARTMENT TO U2; Suppose U1 Wants to Grant U3 the Ability to Select

from EMPLOYEE and DEPARTMENT U1 Allows U3 to Propagate to Other Users

GRANT SELECT ON EMPLOYEE TO U3 WITH GRANT OPTION;

Now, U3 can: GRANT SELECT ON EMPLOYEE TO U4; U4 Cannot Propagate/Delegate this Privilege

Security_BG-79

CSE4701

SQL Examples Suppose U1 Wants to REVOKE U3 the Ability to

Select from EMPLOYEE and DEPARTMENT REVOKE SELECT ON EMPLOYEE TO U3;

Database Must Also Cascade this Revoke to U4 Since U3 No Longer has the Ability to Grant

Cascading Revokes Can be Complicated as Privileges are Defined

Consider 100 Users and DB with 20 Tables and Ability to Grant/Revoke Becomes Complex

Consequently, Propagation/Delegation are Usually Only Given Very Carefully

Critical to Document Security Policy for Each Application!

Security_BG-80

CSE4701

SQL Examples Suppose that U1 wants to Give Back to U3 a Limited

Capability to SELECT from EMPLOYEE Also Allow U3 to be able to Propagate U1 First Creates a View

create view U3_EMP as

select NAME, BDATE, ADDRESS

from EMPLOYEE

where DNO = 5; U1 Now Grants the View

GRANT SELECT ON U3_EMP TO U3 WITH GRANT OPTION;

U1 Can also Grant Limited Update GRANT UPDATE ON EMPLOYEE (SAL) TO U4;

Security_BG-81

CSE4701

Cryptography Information can be Encoded Using a Key it is Written

(or Transferred) -- Encryption Information is then Decoded Using a Key When it is

Read (or Received) -- Decryption Very Widely Used for Secure Network Transmission Mathematical Basis - Prime Number Generation

plaintext ciphertext

encryption

decryption

Security_BG-82

CSE4701 plaintext plaintext

EncryptEncrypt DecryptDecrypt

Ke Kd

C = EKe(plaintext)

More on Cryptography

InvaderInvaderSide information plaintext

Security_BG-83

CSE4701

Cryptographic Systems

Conventional orSymmetric Systems

Modern Systems

Private Key Public Key• Ke and Kd are

essentially the same • Ke and Kd are

private• Ke is public• Kd is private

Cryptographic Systems

Security_BG-84

CSE4701

Statistical Databases are used to Produce Statistics on Various Populations Individual Information is Considered Confidential Users May be Allowed to Access Statistical

Information on the Population, i.e., Applying Statistic Functions to a Population of Tuples

Techniques for Protecting Privacy of Individual Information Solutions are Illustrated by Examples:

Suppose we are Allowed to Retrieve Only the Statistical Information Over this Relation by Using SUM, AVG, MIN, MAX, COUNT, Etc.

Vital for Epidemiology and other Clinical Research

Person(name, ssn, income, address,city, state, zip, sex, last_degree)

Statistical Database Security

Security_BG-85

CSE4701

select COUNT(*) from Personwhere last_degree = “ph.D.”and sex = “F”and city = “Calgary”and state = “Alberta”;

select AVG(income) from Personwhere last_degree = “ph.D.”and sex = “F”and city = “Calgary”and state = “Alberta”;

Q1: find the total number of women who have ph.D. and live in Calgary, Alberta.

Q1: find the average income of women who have ph.D. and live in Calgary, Alberta.

Example of Statistical DB Consider Q1 and Q2:

Suppose Mary Black is a Ph.D who Lives in Calgary and we want to know her Income, which is Prohibited If Query Q1 Returns One Tuple, then the Result of Q2 is

the Income of Mary Otherwise we May Issue a Number of Subsequent Queries

Using MAX and MIN, we May Easily Obtain a Close Range of Mary’s Income

Security_BG-86

CSE4701

The Issue is that Even with Statistical DB Limits, it is Possible to Infer and Discern Confidential Info.

Suppose the Query Writer (Connie) also Lives in Calgary and has a Ph.D.

Consider Q3 (left) and Q4 (right) below:

Since Connie Knows her Own Income, by Calculating Q4 - (Q3 - Connie’s Income), She Determinds Mary’s Income

select SUM(income) from Personwhere last_degree = “ph.D.”and sex = “F”and city = “Calgary”and state = “Alberta”;and name <> “Mary”

select SUM(income) from Personwhere last_degree = “ph.D.”and sex = “F”and city = “Calgary”and state = “Alberta”and name <> “Connie”;

Example Two of Statistical DB

Security_BG-87

CSE4701

Statistical Database Security Thus, having Just Aggregate Operations Can Allow

the Confidentiality of DB to be Breached A Number of Restrictions can be used to Reduce the

Possibility of Deducing Individual Information from Statistical Queries: Statistical Queries are not Permitted if the Number

of Tuples in the Population Specified by the Selection Condition Falls Below Some Threshold

Restricting the Number of Tuples in the Intersection of Subsequent Query Results

Prohibiting Sequences of Queries that Refer Repeatedly to the Same Population of Tuples

While these can help - it may Still Possible to Deduce Information and Breach Confidentiality!

Security_BG-88

CSE4701

Concluding Remarks Security in DB is Part of an Overall Security Strategy

Definition of Security Requirements Realization of Security at Application Level Integration of Security from User to OS to DB Rigorous Definition of Security Policy Dynamic Nature of Security Privileges Enforcement of Defined Privileges at Application

and DB Levels Overall, Security in Today’s World Integral Part of

Everyday Life - Some Key Concerns Confidentiality of an Individuals Data Identity Theft Protecting National Infrastructure