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Domain 5 - ISC2
CISSP - Security Architecture and Models
91
Computer Science
Professional
07/07/2011

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Term
Arithmetic Logic Unit (ALU)
Definition
performs arithmetic and logical operations in binary
Term
BUS
Definition
Computer elements connected via a group of conductors
Term
Three types of BUS
Definition
- Address
- Data
- Control
Term
Cache Memory
Definition
Small amount of very high speed RAM that holds instruction and data from primary memory that is likely to be used in the current operation, increases apparent RAM access time
Term
Random Access Memory
Definition
Memory where locations can be directly addressed and the data that is stored can be altered. It is volatile; lose power = lose data. Multi-phase clock signals used
Term
Dynmaic RAM (DRAM)
Definition
Data is stored in parasitic capacitance and needs to be refreshed – read and rewritten every few milliseconds. Uses a multi-phase clock signals.
Term
Static RAM (SRAM)
Definition
Uses latches to store the bits does not need refreshing. Single-phase clock signals used.
Term
Read Only Memory (ROM)
Definition
- Non-volatile storage where locations can be directly addressed
- Data can not be altered dynamically
- Data remains when power is lost
- Some ROMs can not be altered
Term
Erasable Programmable Read Only Memories (EPROMS) and Electrically Erasable Programmable Read Only Memories
(EEPROMS)
Definition
Other Flash type memories can be altered but slow data transfer compared to other types of memory
Term
Real or Primary Memory
Definition
Directly addressable by the CPU and is usually RAM
Term
Secondary Memory
Definition
- Non-volatile
- Slower
- Example Magnetic Disks
Term
Sequential Memory
Definition
Must be searched from beginning. ample – Magnetic Tape Drive
Term
Virtual Memory
Definition
Uses secondary memory in conjunction with primary memory to present the CPU with more virtual primary memory
Term
Programmable Logic Device
Definition
Integrated circuit with connections or internal logic gates that can be changed through programming. Examples of PLD are Read Only Memory (ROM) and Programmable Array Logic (PAL)
Term
Memory protection
Definition
Means to prevent one program from modifying the memory contents of another. Implemented by the Operating System or the Hardware.
Term
States of Operation
Definition
- Run or operating state
- Application or problem state (Non-privileged instruction – subset of instructions for user)
- Supervisory State (Privileged instructions – System Administrator may execute)
- Wait State (accessing slow memory)
Term
Register Addressing
Definition
Addressing registers within the CPU or registers in the primary memory
Term
Direct Addressing
Definition
Addressing a portion of primary memory with actual address of the memory
Term
Absolute Addressing
Definition
Addressing all of the primary memory space
Term
Indexed Addressing
Definition
Adding the memory address to and index register to then address memory location
Term
Implied Addressing
Definition
Internal register no need to supply the address
Term
Indirect Addressing
Definition
Address specified in the instruction contains final desired location
Term
Pipelining
Definition
Increases performance by overlapping the steps of instructions. Has three Phases; Fetch, Decode, & Execute
Term
Complex Instruction Set
Definition
Instructions perform many operations per instruction, based on taking advantage of longer fetch times
Term
Reduced Instruction Set
Definition
Simpler instruction that require less clock cycles to complete. Faster processors enable the fetch process to be done as quickly as decode and Execute
Term
Scalar Processor
Definition
Processor that executes one instruction at a time
Term
Superscalar Processor
Definition
Processor that enables concurrent execution of multiple instructions in the same pipeline
Term
Very Long Instruction Word Processor – VLIW
Definition
Processor in which a single instruction specifies more than one concurrent operation
Term
Multiprogramming
Definition
Executes two or more programs simultaneously on a single processor
Term
Multitasking
Definition
Executes two or more subprograms at the same time on a single processor
Term
Multiprocessor
Definition
Executes two or more programs at the same time on multiple processors
Term
Types of I/O
Definition
- Block devices (write blocks of data; hard disk)
- Character devices (not addressable; keyboard and printer)
Term
CPU operating states
Definition
Ready State
Problem State
Supervisory State
Wait State
Term
Direct Memory Access – DMA
Definition
Data is transferred directly to and from the memory bypassing the CPU
Term
Interrupt Processing
Definition
An external signal interrupts the normal program flow and requests service, when the service is complete the CPU restores the state of the original program, CPU can turn off interrupts
Term
1st Generation Lauguage
Definition
Machine language: Assembler – translates from assembly language to machine language.
Term
2nd Generation Lauguage
Definition
Assembly language: Disassembler – translates machine language to assembly
Term
3rd Generation Language
Definition
Fortran, BASIC, C languages: Compiler – translates high-level language to machine code.
Term
4th Generation Language
Definition
NATURAL, FOCUS, and database query languages: Decompiler – translates machine language into high-level language.
Term
5th Generation Language
Definition
Prolog, LISP and other Artificial Intelligence languages: Interpreter – translates high-level language one command at time to machine code.
Term
Operating System (OS)
Definition
Program or set of programs that controls the resources and operations of the computer
Term
Controller
Definition
O/S communicates with I/O through controller (i.e. disk controller)
Term
Open systems
Definition
Published specifications, subject to open review and evaluation, vulnerabilities exposed during review.
Term
Closed systems
Definition
Vendor proprietary usually not compatible with other systems, no open review, may have unexposed vulnerabilities
Term
Distributed Computing
Definition
Migration from central computing to the client server model, including desktops.
Term
Protection Domain
Definition
Execution of memory space assigned to each process. Protects from unauthorized modification and executional interference
Term
Trusted Computing Base (TCB)
Definition
Total Combination of protection mechanisms in hardware, software and firmware
Term
Security perimeter
Definition
Separates TCB from the rest of the system
Term
Trusted Path
Definition
Must exist for user to gain protected access to the TCB
Term
Security Kernel
Definition
Hardware, firmware and software (TCB) that implements the Reference Monitor
Term
Reference Monitor
Definition
System component that enforces access control of an object
Term
Security Kernel must
Definition
- Mediate all access
- Be protected from modification
- Be verified as correct
Term
Security Modes
Definition
1) High Mode of Operation – all users have a security clearance or authorization to access the information but not necessarily a need-to-know for all the information processed on the system (only some of the data).
2) Multi Level Operation - Permits two or more classification levels of information to be processed at the same time when all the users do not have the clearance of formal approval to access all the information being processed by the system
3) Dedicated – all users have the clearance or authorization and need-to-know to all data processed within the system.
4) Compartmented – all users have the clearance to access all the information processed by the system, but might not have the need-to-know and formal access approval.
5) Controlled – type of multilevel security limited level of trust in the systems hardware/software
6) Limited Access - minimum level of clearance is uncleared (no clearance) and sensitive but unclassified data
Term
Covert Channel
Definition
Unintended communication path between two resources that allows transfer of information in violation of security policy
Term
Time of Check to Time of Use (TOC/TOU)
Definition
Attack that exploits the difference in time between time security applied and time that service is used
Term
Maintenance Mode
Definition
Allows access only by privileged users
Term
Fault Tolerance
Definition
Allows component of system to fail and recover
Term
Fail Safe System
Definition
Processing is halted if component of system fails
Term
Fail Soft (resilient)
Definition
Non critical processing is halted if component of system fails
Term
Failover
Definition
Switching to duplicate or “hot” backup
Term
Cold Start
Definition
When the TCB and software may be inconsistent and outside intervention is required
Term
Trusted Network Interpretation (TNI)– Red Book
Definition
Addresses confidentiality and integrity in trusted computer/communications network systems
Term
Trusted Computer Security Evaluation Criteria – (TCSEC)
Definition
Part of rainbow series. Basic control objectives of Orange Book:
- Security Policy
- Assurance
- Accountability
Addresses:
- Confidentiality
- NOT Integrity
It looks specifically at the operating system and not other issues
Term
Information Technology Security Evaluation Criteria (ITSEC)
Definition
European Information Technology Security Evaluation Criteria. Addresses confidentiality and integrity and availability. Target of Evaluation (TOE), i.e. system to be evaluated. must have a security target – including security enforcing mechanisms and security policy. Separately evaluates functionality and assurance.
Term
Common Criteria
Definition
TCSEC, ITSEC and Canadian Trusted Computer Product Evaluation Criteria (CTCPEC) have evolved into one common criteria. Defines Protection Profile that specifies the security requirements and protections of the product to be evaluated.
Term
Certification
Definition
Evaluation of technical and non-technical security features to establish how the design meets the security requirements
Term
Accreditation
Definition
A formal declaration by a Designated Approving Authority (DAA) where a system is approved to operate in a security mode
Term
Phases of DITSCAP
Definition
- Definition – understanding of environment and architecture
- Verification – Verify compliance with System Security Authorization (While evolving)
- Validation - Validate compliance with System Security Authorization (final)
- Post Accreditation – continuing operation
Term
Types of NIACAP accreditation
Definition
- Site accreditation – evaluates application at self contained location
- Type accreditation – evaluates application at number of locations
- System accreditation - evaluates a major application or support system
Term
Information Security Models
Definition
- Access control models
- Integrity Models
- Information Flow Models
Term
Access Control Models
Definition
- Access Matrix
- Take-Grant
- Bell-Lapadula Confidentiality
- State Machine
Term
Access Matrix
Definition
Straight Forward provides access rights to subjects for objects.
- Access Rights – Read, write and execute
- Subject – can be a person or a program
- Objects – file or storage device
- Columns - are called Access Control Lists
- Rows - are capability lists
- Supports Discretionary Access Control
- Triple - Subjects capability is defined by a triple (object, rights, random#)
- The random number prevents spoofing
Term
Take-Grant Model
Definition
Uses a directed graph to specify the rights a subject can transfer to an object or take from another subject.
Term
Bell-Lapadula
Definition
Confidentiality model
- Developed to formalize the US Department of Defense multilevel security policy
- Only deals with confidentiality does not deal with integrity or availability
- Based on Government Classification – Unclassified, Sensitive But Unclassified (SBU), Confidential, Secret, Top Secret
- Must have need to know
- A Trusted Subject can violate the *property
- Does not address client/server model
- Based on State Machine Concept
- Starts at secure state and transitions from one state to another.
- The initial state must be secure and the transitions result in a secure state
Term
Simple Security Property (ss Property)
Definition
Bell-Lapadula Security State meaning no reading from lower subject to higher object (No Read Up)
Term
(*) Star security Property
Definition
Bell-Lapadula Security State meaning no writing from higher subject to lower object (No write Down)
Term
Discretionary Security Property
Definition
Bell-Lapadula Security State that uses Access Matrix to specify discretionary access control
Term
Content Dependent
Definition
Discretionary access decisions based on data contained in the object data.
Term
Context Dependent
Definition
Discretionary access based on subject or object attributes to make these decisions (i.e. job role, earlier accesses, and file creation dates and times).
Term
Weakness of Bell-Lapadula Modell
Definition
- Does not address covert channels
- Does not address modern systems that use file sharing and server
- Does not define secure state transition
- Based on multilevel security does not address other policy types
Term
Integrity Models
Definition
- Biba
- Clark-Wilson
Term
Simple Integrity Axiom
Definition
No reading of lower object from higher subject (No Read Down)
Term
(*) Star Integrity Axiom
Definition
No writing from lower subject to higher object (No write Up)
Term
3rd Integrity Axiom
Definition
A subject at a lower level of integrity can not invoke a subject at a higher level of integrity
Term
Biba Integrity Model
Definition
Integrity defined by three goals
1) Data protected from modification by unauthorized users
2) Data protected from unauthorized modification by authorized users
3) Data is internally and externally consistent.
Developed in 1977 as an integrity add on to Bell-Lapadula
- Lattice Based uses less than or equal to relation
- A lattice structure is a set with a least upper bound (LUB) and a greatest lower bound (GLB)
- Lattice represents a set of integrity classes (IC) and an ordered relationship
- Lattice = (IC, , LUB, GUB)
Term
Clark-Wilson Integrity Model
Definition
Contains two elements: well formed transaction and separation of duties.
- Developed in 1987 for use in real-world commercial environment
- Addresses the three integrity goals
- Constrained Data Item (CDI) – A data Item whose integrity is to be preserved
- Integrity Verification Procedure (IVP) – confirms that all CDIs have integrity
- Transformation Procedure (TP) – transforms a CDI from one integrity state to another integrity state
- Unconstrained Data Item – data items outside of the control area of the modeled environment
- Requires Integrity Labels
Term
Information Flow Models
Definition
- Each object and subject is assigned security class and value; info is constrained to flow in directions that are permitted by the security policy.
- Based on state machine and consists of objects, state transitions and lattice (flow policy) states.
- Object can be a user
- Each object is assigned a security class and value
- Information is constrained to flow in the directions permitted by the policy
Term
Non-interference Model
Definition
Actions of group A using commands C are not seen by users in Group B using commands D
Term
Composition Theories
Definition
When smaller systems are combined they must maintain the component system security properties
Term
External Constructs
Definition
1) Cascading – one systems input is the output of another
2) Feedback – one systems output is input to another system and returned as input to the first system
3) Hookup – a system that communicates with another system and external entities
Term
Internal Constructs
Definition
- Intersection
- Union
- Difference
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