1ACSAC 2002 © Mohammad al-Kahtani 2002

A Model for Attribute-Based User-Role Assignment

Mohammad A. Al-Kahtani Ravi Sandhu George Mason University SingleSignOn.net, Inc. & malkahta@gmu.edu George Mason University

sandhu@gmu.edu

2ACSAC 2002 © Mohammad al-Kahtani 2002

Presentation Roadmap

1. Introduction2. Problem Description3. Suggested Solution 4. Case Study 5. Expressing MAC

3ACSAC 2002 © Mohammad al-Kahtani 2002

Introduction

• Role-Based Access Control (RBAC): A proven alternative to DAC and MAC

• RBAC basic components:1. Users2. Roles3. Permissions

4ACSAC 2002 © Mohammad al-Kahtani 2002

Introduction

• Simplified RBAC Model

RoleHierarchy

Users

(UA) User

Assignment

(PA) Permission Assignment

RolesPermiss-ions

5ACSAC 2002 © Mohammad al-Kahtani 2002

Presentation Roadmap

1. Introduction2. Problem Description3. Suggested Solution4. Case Study 5. Expressing MAC

6ACSAC 2002 © Mohammad al-Kahtani 2002

Problem Description

• In RBAC, user-to-role assignment is done manually

• Many enterprises have huge customer bases: Banks Utilities companies Popular web sties

• Manual assignment becomes a formidable task

7ACSAC 2002 © Mohammad al-Kahtani 2002

Presentation Roadmap

1. Introduction2. Problem Description3. Suggested Solution4. Case Study 5. Expressing MAC

8ACSAC 2002 © Mohammad al-Kahtani 2002

Suggested Solution

• Modify RBAC to allow automatic user-role assignment

Introducing Authorization Rules

• Authorization rule structure:

Constraints

AttributesExpression

Roles

9ACSAC 2002 © Mohammad al-Kahtani 2002

Suggested Solution

• Rule-Based RBAC (RB-RBAC)

AttributesExpressions

Users

Roles

Permissions

Constraints

Attributesvalues

10ACSAC 2002 © Mohammad al-Kahtani 2002

Suggested Solution

• Attributes Values:

1. Stored locally

2. Provided by users

3. Other means

AttributesExpressions

Users

Roles

Permissions

Constraints

Attributesvalues

11ACSAC 2002 © Mohammad al-Kahtani 2002

Suggested Solution

• Attributes Expressions:

1. Expressed in RB-RBAC language

2. Constitute LHS of authorization rules

• RB-RBAC production rules are in BNF notation.

AttributesExpressions

Users

Roles

Permissions

Constraints

Attributesvalues

12ACSAC 2002 © Mohammad al-Kahtani 2002

Suggested Solution

• Constraints:

Future work

AttributesExpressions

Users

Roles

Permissions

Constraints

Attributesvalues

13ACSAC 2002 © Mohammad al-Kahtani 2002

Suggested Solution

• Seniority Levels Relations among authorization rules

• Rule i:

• Rule j:

Rulei is senior to Rulej

AttributesExpression

Roles

AttributesExpression

Roles

Logically implies

14ACSAC 2002 © Mohammad al-Kahtani 2002

Suggested Solution

• Seniority Levels Anomalies

1. Redundancy

Rule i is senior to Rule j

Rule i

Rule j

Role 1

Role 1 & Role 2

15ACSAC 2002 © Mohammad al-Kahtani 2002

Suggested Solution

• Seniority Levels anomalies

1. Redundancy

Rule i is senior to Rule j

Rule i

Rule j

Role 1

Role 2

Role 1 is senior to Role 2

16ACSAC 2002 © Mohammad al-Kahtani 2002

Suggested Solution

• Seniority Levels anomalies

2. Inconsistency

Rule i is senior to Rule j

Rule i

Rule j

Role 1

Role 2

Role 1 and 2 are mutually exclusive

17ACSAC 2002 © Mohammad al-Kahtani 2002

Presentation Roadmap

1. Introduction2. Problem Description3. Suggested Solution4. Case Study 5. Expressing MAC

18ACSAC 2002 © Mohammad al-Kahtani 2002

Case Study

• Online Entertainment Store

• Suggested rating system

• Attributes Age Country

Rating Levels Roles

Strict Child

Less Strict Juvenile

Liberal Adolescent

Graphic Adult

19ACSAC 2002 © Mohammad al-Kahtani 2002

Case Study

• Attributes: Age

1. Rule 1:: (Age 3) Child2. Rule 2:: (Age 11) Juvenile3. Rule 3:: (Age 16) Adolescent

4. Rule 4:: (Age 18) Adult

Age Role

3 Child

11 Juvenile

16 Adolescent

18 Adult

20ACSAC 2002 © Mohammad al-Kahtani 2002

Case Study

• Attributes: Country

1. Rule 1:: (Country IN {A..Z}) Juvenile 2. Rule 2:: (Country IN {{A..Z} – {Saudi, Sudan}}) Adolescent 3. Rule 3:: (Country IN {{A..Z} – {China, India, Saudi, Sudan, Egypt, Indonesia, Malaysia, Singapore}}) Adult

Country Role

Country in {A..Z} Juvenile

Country in {{A..Z} – {Saudi, Sudan}}

Adolescent

Country in {{A..Z}

– {China, India, Saudi, Sudan, Egypt, Indonesia, Malaysia, Singapore}}

Adult

21ACSAC 2002 © Mohammad al-Kahtani 2002

Case Study

• Authorization rules for the 2 attributes:

1. Rule 1:: (Age 3) AND (country IN {A..Z}) Child 2. Rule 2:: (Age 11) AND (country IN {A..Z}) Juvenile3. Rule 3:: (Age 16) AND (country IN {{A..Z} –   {Saudi, Sudan}}) Adolescent4. Rule 4:: (Age 18) AND (Country IN {{A..Z} – {China, India, Saudi, Sudan, Egypt, Indonesia, Malaysia, Singapore }}) Adult

22ACSAC 2002 © Mohammad al-Kahtani 2002

Presentation Roadmap

1. Introduction2. Problem Description3. Suggested Solution4. Case Study 5. Expressing MAC

23ACSAC 2002 © Mohammad al-Kahtani 2002

Expressing MAC

Adult

Adolescent

Juvenile

Child

Adult Write(AW)

Adolescent Write(DW)

Juvenile Write(JW)

Child Write(CW)

Security Lattice

Role Hierarchies

Adolescent Read (DR)

Juvenile Read (JR)

Child Read (CR)

Adult Read (AR)

24ACSAC 2002 © Mohammad al-Kahtani 2002

Expressing MAC

Authorization Rules:

Rule 1:: (Age 3) AND (country IN {A..Z}) CR AND CW

Rule 2:: (Age 11) AND (country IN {A..Z}) JR AND JW

Rule 3:: (Age 16) AND (country IN {{A..Z} – {Saudi, Sudan}})

DR AND DW

Rule 4:: (Age 18) AND (Country IN {{A..Z} –{China, India,

Saudi, Sudan, Egypt, Indonesia, Malaysia, Singapore}})

AR AND AW