Systems Engineering & Modeling (194)
Common Criteria ISO 15408 - Structured methodology for
documenting security requirements, documenting and
validating ****
A SECURITY PRODUCT MAY BE CERTIFIED
Defines a protection profile that specifies the security
requirements and protections of a product that is to be evaluated.
Organized around TCB entities. Evaluation Assurance Levels
(EAL)
- EAL0 –Inadequate assurance
- EAL1 –Functionally tested
- EAL2 –Structurally tested
- EAL3 –Methodically tested and checked
- EAL4 –Methodically designed, tested and reviewed
- EAL5 –Semi formally designed and tested
- EAL6 –Semi formally verified design and tested
- EAL7 –Formally verified design and tested
Target of Evaluation (TOE): the product
Protection Profile (PP): set of security requirements for a category
of products that meet specific consumer security needs
Security Target (ST): identifies the security properties of TOE
Security Functional Requirements (SFRs): Specific individual
security functions
Engineering Principles for IT Security (194)
NIST SP 800-27
Initiation; need expressed, purpose documented, impact
assessment
Development/Acquisition; system designed, purchased,
programmed, developed or constructed.
Implementation; system tested and installed, certification
and accreditation
Operation/Maintenance; performs function, security
operations, audits
Disposal; disposition of information, HW and SW
Physical controls are your first line of defense, and people are
your last.
ISO/IEC 21827:2008 SSE-CMM (Maturity Model)
(196)
BIGGEST JUMP IN MATURITY MODEL? 2 – 3. FROM
REACTIVE TO PROACTIVE
Loads & runs binary programs, schedules task swapping,
allocates memory & tracks physical location of files on computers
hard disk, manages IO/OP requests from software, & translates
them into instructions for CPU
Common System Components (198)
Primary Storage – is a temporary storage area for data entering
and leaving the CPU
Random Access Memory (RAM) – is a temporary holding place
for data used by the operating systems. It is volatile; meaning if it
is turned off the data will be lost. Two types of RAM are dynamic
and static. Dynamic RAM needs to be refreshed from time to time
or the data will be lost. Static RAM does not need to be refreshed.
Read-Only Memory (ROM) – is non-volatile, which means when a
computer is turned off the data is not lost; for the most part ROM
cannot be altered. ROM is sometimes referred to as firmware.
Erasable and Programmable Read-Only Memory (EPROM) is non-
volatile like ROM, however EPROM can be altered.
Process states:
- Stopped; process finishes or must be terminated
- Waiting; the process is ready for continued execution but
is waiting for a device or access request
- Running; executes on the CPU and keeps going until it
finishes, its time slice expires, or it is blocked
- Ready; process prepared to execute when CPU ready
Multitasking – execute more than one task at the same
time
Multiprocessing – more than one CPU is involved.
Multi-Threading: execute different parts of a program
simultaneously
Single state machine – operates in the security environment at
the
highest level of classification of the information within the
computer. In other words, all users on that system must have
clearance to access the info on that system.
Multi-state machine – can offer several security levels without risk
of compromising the system’s integrity.
CICS – complex instructions. Many operations per instruction. Less
number of fetches
RISC – reduced instructions. Simpler operations per instruction.
More fetches.
Software
1 GL: machine language (used directly by a computer)
2GL: assembler
3GL: FORTRAN. Basic pl/1 and C++
4GL: Natural / focus and SQL
5GL: Prolog, lisp artificial intelligence languages based on logic
Segmentation – dividing a computer’s memory into segments.
Protection Keying – Numerical values, Divides physical memory
up into particular sized blocks, each of which has an associated
numerical value called a protection key.
Paging – divides memory address space into even size blocks
called pages. To emulate that we have more RAM than we have.
SYSTEM KERNAL KNOWS THE LOCATION OF THE PAGE FILE
DEP, Data Execution Prevention – a system-level
memory protection feature that is built into the OS
DEP prevents code from being run from data pages
such as the default heap, stacks, and memory pools.
The ITIL Core includes five publications addressing the overall life
cycle of systems. ITIL as a whole identifies best practices that an
organization can adopt to increase overall availability, and the
Service Transition publication addresses configuration
management and change management processes.
- Service Strategy
- Service Design
- Service Transition
- Service Operations
- Continuous Service Improvement
Types of Security Models (210)
Defining allowed interactions between subjects (active parties) and
objects (passive parties) at a particular moment in time.
State Machine Model – describes a system that is always secure
no matter what state it is in. If all aspects of a state meet the
requirements of the security policy, that state is considered
secure. A transition occurs when accepting input or producing
output. A transition always results in a new state (also called a
state transition). A secure state machine model system always
boots into a secure state, maintains a secure state across all
transitions, and allows subjects to access resources only in a
secure manner compliant with the security policy.
Information Flow Model – focuses on the flow of information.
Information flow models are based on a state machine model. The
Bell-LaPadula and Biba models are both information flow models.
Information flow models don’t necessarily deal with only the
direction of information flow; they can also address the type of
flow. Information flow models are designed to prevent
unauthorized, insecure, or restricted information flow, often
between different levels of security (these are often referred to as
multilevel models). The information flow model also addresses
covert channels by specifically excluding all non-defined flow
pathways.
Noninterference Model – is loosely based on the information flow
model. However, instead of being concerned about the flow of
information, the noninterference model is concerned with how the
actions of a subject at a higher security level affect the system
state or the actions of a subject at a lower security level. Basically,
the actions of subject A (high) should not affect the actions of
subject B (low) or even be noticed by subject B. The
noninterference model can be imposed to provide a form of
protection against damage caused by malicious programs such as
Trojan horses. Southerland Model
Techniques for Ensuring CIA
Confinement – to restrict the actions of a program. Simply put,
process confinement allows a process to read from and write to
only certain memory locations and resources. This is also known
as sandboxing.
Bounds – a process consist of limits set on the memory addresses
and resources it can access. The bounds state the area within
which a process is confined or contained.
Isolation – When a process is confined through enforcing access
bounds that process runs in isolation. Process isolation ensures
that any behavior will affect only the memory and resources
associated with the isolated process.