Principles of Security Model Slide ke-12 Mata Kuliah: Keamanan Jaringan oleh Setio Basuki

  Principles of Security Model

Slide ke-12 Mata Kuliah: Keamanan Jaringan

Course Objectives

  Security Models, Subjects and

Objects, Understanding System

Security and Evaluation, Common

Flaws and Security Issue.

  

Security Models

• In information security, models provide a way to formalize security policies.
• – Provide an explicit set of rules that a computer can follow to implement the

  fundamental security concepts, processes,

  and procedures that make up a security policy.

  developers can be sure their

• In this way,

  

Security Models (Cont.)

• You’ll explore

  several security models in

  the following sections: 1. Trusted computing base.

  2. State machine model.

  3. Take-Grant model.

  4. Access control matrix.

  

Security Models (Cont.)

• You’ll explore

  several security models in

  the following sections: 6. Biba.

  7. Clark-Wilson.

  

8. Brewer and Nash model (also known as

Chinese Wall).

  Trusted Computing Based (TCB)

• Trusted computing base (TCB) as a

Combination of hardware, software

  and controls that work together to form a trusted base, to enforce your security policy.

  Trusted Computing Based (TCB)

  

State Machine Model

• It is based on the Computer Science definition of a Finite State Machine (FSM).

  

Take Grant Model (1)

• The Take-Grant model employs a directed graph to dictate how rights can be

  passed from one subject to another or from a subject to an object.

• Simply put, a

  subject with the grant right can grant another subject or another Take Grant Model (2)

  

Access Control Matrix (1)

• An access control matrix is

  a table of

subjects and objects that indicates the

  actions or functions that each subject can perform on each object.

• Each column of the matrix is an

  access control list (ACL). Each row of the matrix Access Control Matrix (2)

  

Bell-LaPadula Model (1)

• The U.S. Department of Defense (DoD) developed the Bell-LaPadula model in the 1970s to address concerns about protecting classified information .

  

Bell-LaPadula Model (2)

• There are

  : Three Basic Properties he Simple Security Property states that a subject

• – T

  may Not Read Information at a Higher Sensitivity Level (no read up).

• – The * (star) Security Property states that a subject

  may Not Write Information to an Object at a Lower Sensitivity Level (no write down). This is also known as the confinement property .

  Bell-LaPadula Model (3)

  

Biba Model (1)

• For many nonmilitary organizations

  , in this case integrity is more important than confidentiality.

• The Biba model was designed after the Bell-LaPadula model.

  Bell-LaPadula model addresses

• – Where the

  confidentiality , the Biba model addresses

  Biba Model (2)

• Here are the

  Basic Properties of the

  Biba model state machine:

  states that a

• – The Simple Integrity Property

  

subject cannot read an object at a lower

integrity level (no read down).

• – The * (star) Integrity Property states that a

  subject cannot modify an object at a higher

  Biba Model (3)

  

Clark-Wilson Model (1)

• Although the Biba model works in commercial applications, another model was designed in 1987 specifically for the commercial environment.
• The

  Clark-Wilson model uses a Multifaceted Approach to enforcing data

  

Clark-Wilson Model (2)

• Clark-Wilson defines the following

  items and procedures :

  1. A constrained data item (CDI) is any data item

whose integrity is protected by the security

model.

  2. An unconstrained data item (UDI) is any data item that is not controlled by the security model.

  

Clark-Wilson Model (3)

• Clark-Wilson defines the following items and procedures:

  only procedures that are allowed to modify a CDI. The limited access to CDIs through TPs forms the backbone of the Clark-Wilson integrity model.

  

Brewer and Nash Model (1)

• This model was created to permit access

  controls to change dynamically based on a user’s previous activity.

• Individuals are only allowed to access data that is not in conflict with data they accessed previously.

  Brewer and Nash Model (2)

Objects and Subjects Systems • Closed and Open System

• Technique for Ensuring Confidentiality, Integrity, and Availability.
• Trust and Assurance.

  

Objects and Subjects Systems

• Systems are designed and built according to one of two differing philosophies:

  and .

• –Closed Open Systems
• A Closed System is designed to work

  well with a narrow range of other systems, generally all from the same manufacturer.

  

Closed System (1)

• Closed systems are

  Harder To Integrate

  with unlike systems, but they can be more secure.

• – A Closed System often comprises proprietary hardware and software that does not incorporate industry standards.

  Closed System (2)

• In many cases,

  attacking a closed system is harder than launching an attack on an open system.

• – In addition to the lack of known vulnerable components on a closed system, it is often

  necessary to possess more in-depth

  knowledge of the specific target system to

  Open System (1)

• • Open Systems , on the other hand, are

  designed using agreed-upon industry standards.

• Open systems are much easier to

  integrate with systems from different

  manufacturers that support the same

  

Open System (2)

• Open systems are generally

  far easier to integrate with other open systems.

• – The openness makes them more

  vulnerable to attack , and their widespread availability makes it possible for attackers to find plenty of potential targets.

  Techniques for Ensuring Confidentiality, Integrity, and Availability.

• Confinement.
• Bounds.
• Isolation.

  

Confinement

• Process confinement

  allows a process to read from and write to only certain memory locations and resources .

• – If a process attempts to initiate an action beyond its granted authority, that action

  will be denied .

  

Bounds

• Each Process

  that runs on a system is

  assigned an authority level that tells the

  operating system what the process can do.

• The bounds of a

  Process Consist of Limits Set on the memory addresses and

  

Isolation

• When a process is confined through enforcing access bounds, that process runs in isolation .
• – These three concepts (

  confinement, ) make designing bounds, and isolation secure programs and operating systems more difficult, but they also make it possible to

  

Trust and Assurance (1)

• A Trusted System

  is one in which all protection mechanisms Work Together to process sensitive data for many types of users while maintaining a stable and secure computing environment.

• Assurance

  is simply defined as the

  Continually

Maintained, Updated, and Reverified

.

  

Trust and Assurance (2)

• Assurance must be

  

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