Security Architecture and Design

Chapter 4Part 1

Pages 297 to 319

Bugs and Flaws

• Security Bug– Vulnerability in the software

• Security Flaw– Vulnerability in the architecture or design

• About 50%-50%

Today’s Environment

• Security bug and flaws account for the majority of compromises

• We are better at protecting the perimeter with Firewalls, IPS, etc.

• More demands for functionality has made software more complex

• As complexity increases security decreases

Approaches

• Bake Security In from the start– From Architecture to Design to Implementation to

Testing– Correct approach

• Bolt Security on at the end– Often not enough time– Much harder to do

Security

• “The security that a product provides must be evaluated based upon the availability, integrity, and confidentiality that it claims to provide.”

• Need to really understand how technology works to determine the proper level of security that is truly in place.

Waterfall Model

• Architect the system• Write Specification Requirements• Design• Implement = code• Test• Deploy

System Architecture

• Conceptually understand the system structure and behavior and its relationship to its environment

• Outline the main goals the system must achieve

• Big picture

System Architecture

• Architectural Description for a software intensive system– ISO/IEC/IEEEE 42010

• Security needs to be considered while architecting the system

Stakeholder

• Stakeholder – Individual, team, or organization with interest in the system

• View – representation of the system from a particular perspective

• “The architect needs to capture the goals that the system is supposed to accomplish for each stakeholder.”

Computer Architecture

• Computer hardware• Operating system• Network

Computers

Buses

• Most systems today have 64-bit address and data buses

CPU

Registers

• PC (Program Counter) – address of next instruction

• General Registers – Hold data• Special Registers– SP (Stack pointer)– PSW (Program Status Word)• Bit of negative result • Bit for Zero result

PSW

• Bit for mode– User mode (where applications run)– Privileged (Kernel, Supervisor) mode for Operating

System• I/O

Stack Pointer

• Local Variables• Return Address• Parameters• Local Variable• Return Address• Parameters

Multicore Processor

Multiprocessing (See page 311)

Process

• Program loaded in memory• Multiprogramming OS – more than one

process (program) can be loaded in memory (See page 319)

• Preemptive multitasking – time sharing

Figure 4-6 on Page 314

Process Table

Interrupts

• Timer• Device – When a device needs to

communicate with the CPU – Disk completed I/O operation

Interrupts

Threads

• Instructions generated by a process when it has a specific activity that needs to be carried out by the operating system.

• Microsoft Word– Open a file– Print a document– Save a file

Mulithreading

Code Injection Attack

• Attacker injects instructions into a running process.

• Keylogger, send out malware, • If running at privilege mode• OWASP Top Ten– https://

www.owasp.org/index.php/Top_10_2013-Top_10– A9 Using Components with Known Vulnerabilities

Process Scheduling

• Responsibility of the operating system• Process priorities– Low priority background process– High priority process hogging the system

resources• Denial of Services attack

Software Deadlock

• A has resources 1 and requests 2• B has resource 2 and requests 1