Chapter 11: Principles of Security Models, Design, and Capabilities Flashcards
In information security, what is the purpose of a model?
It provides a way to formalize security policies.
What is the Trusted Computing Base, or TCB?
From the “Orange Book”, a combination of hardware, software, and controls that work together to form a trusted base to enforce your security policy.
It’s the only portion of a computer system that can be trusted to adhere to and enforce the security policy.
What is the security perimeter of a system?
An imaginary boundary that separates the TCB from the rest of the system.
What is a trusted path?
A secure channel created from the TCB to the rest of the system.
What is a reference monitor or kernel?
The part of the TCB that validates access to every resource prior to granting access requests.
What is the State Machine Model?
It describes a system that is always secure no matter what state it is in.
What is the Information Flow Model?
A model that focuses on the flow of information. Based on a state machine model. Designed to prevent unauthorized, insecure, or restricted information flow, often between different levels of security.
What is a Noninterference Model?
Loosely based on the Information Flow Model. Basically concerned with insuring that actions at a higher security level don’t affect anything at lower security model to avoid allowing objects or users at a lower security state from making inferences about the higher security state.
What is the Take-Grant model?
A model that employs a directed graph to distate how rights can be passed from one subject to another or from a subject to an object.
What is an Access Control Matrix?
A table of subjects and objects that indicate the actions or functions that each subject can perform on each object. Each column is an ACL. Each row is a capabilities list.
What is involved in constructing an ACL?
Implementing an environment that can create and manage lists of subjects and objects
Crafting a function that can return the type associated with an object
What is the Bell-LaPadula model?
A multilevel model that’s usually limited to unclassified, sensitive but unclassified, confidential, secret, and top-secret. A subject with any level of clearance can access resources at or below its clearance level, but at the higher levels, need to know applies.
What is the Simple Security Property?
A subject may not read information at a higher sensitivity level (no read up)
What is the * (star) Security Property?
A subject may not write information to an object a alower sensitivity level (no write down). AKA the confinement property.
What is the Discretionary Security Property
The system uses an access matrix to enforce discretionary access control.
Of the CIA triad, what does Bell-LaPadula address?
Only confidentiality. It does nothing for Integrity or Availability.
What three issues does the Biba model address?
Prevent modification of objects by unauthorized subjects
Prevent unauthorized modifications of objects by authorized subjects
Protect internal and external object consistency.
Biba provides integrity where Bell-LaPadula does not.
What is the Clark-Wilson Model?
Defines each data item and allows modifications only through a small set of programs. Subjects don’t have direct access to objects. Objects can only be accessed by programs. If you aren’t supposed to access the object, you aren’t given access to the program.
What is the Brewer and Nash Model?
AKA Chinese Wall.
What is a subject?
A user or process that makes a request to access a resource.
What is an object?
The resource a user or process accesses.