Symmetric mode - the processors are handed work as needed. Think load balancing.

Asymmetric mode - at least one processor is dedicated solely to a specific task or application.

Cooperative multitasking - required processes to voluntarily release the resources they were using.

Preemptive multitasking - the operating system controls how long a process can use a resource (time sharing).

Develop better code that releases memory properly.

Use a garbage collector program that identifies unused memory and forces its release.

A combination of RAM and the use of secondary (nonvolatile) storage like the computer's hard drive, external drives or CD-ROMs.

• Ring 0 - Operating system kernel
• Ring 1 - Remainder of OS
• Ring 2 - Drivers/utilities
• Ring 3 - Apps/software and user activity
  

They are terms used when talking about protection mechanisms for OSs. Processes can only exchange data through well-defined APIs). No API interface = no communication between layers/programs.

A communication channel between a program or a user and the kernel.

The code in it cannot bust out of it and no other process can bust in

1. It must provide isolation for the tamperproof processes.

2. It must be invoked for every access attempt and be impossible to circumvent.

3. It must be small enough to be completely and comprehensively tested and verified.

One that prevents information from flowing from a higher security level to a lower one.

Of the following security models, which one is informal and used more as a framework?

Bell-LaPadula

Biba

Clark-Wilson

It is used to describe the behavior of a system to different inputs. It will ensure the system that uses this model will be in a secure state at all times – boot up, command execution, shut down and even failing!  Such a system will only allow a change of state after (a) authorization is checked and (b) consequence of this change (still secure state after change?) is checked - think conditional statements "if condition then update".

A subject cannot write data to an object with a higher integrity level.

1. Prevent unauthorized users from making modifications.

2. Prevent authorized users from making improper modifications.

3. Maintain internal and external consistency.

Users (subjects)

Transformation procedures (TPs)

Constrained data items (CDIs)

Unconstrained data item s (UDIs)

Integrity verification procedures (IVPs)

A model that protects confidentiality by defining upper and lower bounds of access (need to know) in a MAC based, clearance based approach.

For example based on your clearance your least upper bound may allow you to read a file, your greatest lower bound may NOT allow you to write to it.

The types of users directly or indirectly connection to the system.

The type of data (classification levels, compartments, and categories) processed on the system.

The clearance levels, need to know, and formal access approvals the users will have.

This mode permits two or more classification levels of information to be processed at the same time when not all of the users have the clearance or formal approval to access all the information being processed by the system.

The user cannot access all the data on the system, only what they are cleared to access.

Compartmented security requires the user to have a clearance level that dominates all data on the system.

Multilevel security only requires the user to have clearance to access the data with which they will be working.

A. Verified protection - the highest level of assurance

B. Mandatory protection

C. Discretionary protection

D. Minimal security - lowest level of assurance. Systems that are rated at this level have failed to meet the criteria for the higher divisions

Security policy - must be explicit, well defined and enforced

Identification - Subjects must be uniquely identified

Labels - Access control labels must be associated properly with objects

Documentation - Must be provided (test, design and spec docs, user guides and manuals)

Accountability - Audit data must be captured

Life-cycle assurance - software, hardware and firmware must be able to be tested individually

Continuous protection - security mechanisms and the whole system must perform predictably, acceptably and continuously.

C1 - Discretionary Security Protection - access control is based on individuals and/or groups.

C2 - Controlled Access Protection (higher rating than C1) - Logical access control mechanisms. Object reuse must also be invoked.

B1 - Labeled Security - data objects must contain a classification label and each subject must have a clearance level.

B2 - Structured Protection - system must not allow covert channels. A trusted path must exist for logon and authentication processes. Operator and administration functions are separated within the system for more trusted and protected operational functionality.

B3 - Security Domains - more grainular protection mechanisms and unecessary code is removed. The reference monitor plays a key role in this raiting.

EAL1 - Functionally tested

EAL2 - Structurally tested

EAL3 - Methodically tested and checked

EAL4 - Methodically designed, tested and reviewed

EAL5 - Semiformally designed and tested

EAL6 - Semiformally verified design and tested

EAL7 - Formally verified design and tested

Storage - processes are able to communicate through some type of storage space on the system.

Timing - processes are able to relay information by modulating its use of system resources.

These deal with the sequence steps systems use to complete tasks. It takes advantage of the dependency on the timing of events in multitasking operating systems.

Example: If an attacker can get in between the authentication and the open of a file and exchange the non-critical file that is opened with a sensitive one, he is able to view the protected content.

When multiple processes compete for the same resource.

Example: If an attacker disturbs the order successfully, he/she could be authorized before authenticated.

The operating system should apply software locks to the items it will use while carrying out its "checking" tasks.

Proper programming that includes bounds checking (input validation).