CMU5XX-INFOSEC

Information Security for Industry

Session 1: Secure IS & Architecture

James Williams

jwilliams@staff.newman.ac.uk

Learning Objectives

  • Define the core concepts of Secure Information Systems (IS).
  • Deconstruct the CIA Triad (Confidentiality, Integrity, Availability) in a corporate context.
  • Analyze standard enterprise network architectures and defense-in-depth strategies.
  • Identify the primary components of an Information System (People, Process, Technology).
  • Evaluate the transition from perimeter defense to Zero Trust Architecture.

Seminar Structure (3 Hours)

Part 1: The Foundations of IS (1.5 hrs)
  • What is an Information System?
  • The CIA Triad and the McCumber Cube
  • Task 1: System Component Analysis
Part 2: Secure Architecture (1.5 hrs)
  • Defense in Depth vs Zero Trust
  • Network Segmentation and DMZs
  • Task 2: Architectural Review

Part 1: The Foundations of IS

Duration: 1.5 Hours

What is an Information System?

An IS is not just a server or a piece of software. It is a holistic ecosystem.

  • Technology: Hardware, software, databases, and networks.
  • People: Users, administrators, executives, and third-party vendors.
  • Process: The documented procedures (e.g., onboarding, data disposal) that dictate how the people interact with the technology.
  • A failure in any one of these pillars results in a total system failure.

The CIA Triad

The foundation of all security design.

  • Confidentiality: Preventing unauthorized disclosure (Encryption, Access Control).
  • Integrity: Preventing unauthorized modification (Hashing, Digital Signatures, File Integrity Monitoring).
  • Availability: Ensuring authorized access when needed (Redundancy, Backups, DDoS mitigation).
  • Trade-offs: Maximizing confidentiality (e.g., locking servers in a vault) inherently reduces availability. Security is about balancing these three based on business needs.

The McCumber Cube

A framework for evaluating information security comprehensively.

  • Dimension 1: Information States (Storage, Transmission, Processing).
  • Dimension 2: Security Goals (Confidentiality, Integrity, Availability).
  • Dimension 3: Countermeasures (Technology, Policy/Practices, Human Factors).
  • When assessing a system, you must check every intersection (e.g., "Do we have a *Policy* for the *Integrity* of data in *Transmission*?").

Introduction to Task 1

Security analysts must look beyond firewalls and code to see the entire business process.

We will analyze a common corporate system to identify the critical intersections of People, Process, and Technology.

Task 1: System Component Analysis

Timing: 45 minutes

Consider a hospital's Electronic Health Record (EHR) system.

  1. Identify one critical element for each of the three IS pillars: Technology, People, and Process.
  2. For each element identified, describe a specific threat that could compromise the Integrity of the patient data.
  3. Propose one countermeasure for each threat. Classify your countermeasures as either Technical, Administrative, or Physical.

15 Minute Break

Please return promptly for Part 2.

Part 2: Secure Architecture

Duration: 1.5 Hours

Defense in Depth (The Castle Approach)

Relying on multiple, independent layers of security controls.

  • If a hacker bypasses the perimeter firewall, they still have to beat the Intrusion Detection System (IDS).
  • If they beat the IDS, they still have to crack the database encryption.
  • The Perimeter Problem: Traditional architecture assumes the "inside" of the network is safe, and the "outside" (the internet) is dangerous. This fails completely when an employee clicks a phishing link and the attacker is already "inside."

Network Segmentation & DMZs

Limiting the blast radius of a breach.

  • Demilitarized Zone (DMZ): A subnetwork containing public-facing services (e.g., Web Servers, Email Relays). It is exposed to the internet, but strictly firewalled off from the internal corporate network.
  • VLANs: Logically dividing the internal network so the HR department cannot communicate with the Engineering department's servers, preventing lateral movement by malware (like ransomware).

Zero Trust Architecture (ZTA)

"Never Trust, Always Verify."

  • ZTA assumes the network is already compromised.
  • Location (being inside the corporate office or on the corporate VPN) grants zero implicit trust.
  • Every single request to every single resource must be authenticated and authorized based on dynamic context (User Identity + Device Health + Geolocation + Time of Day).
Practical Resource: NIST SP 800-207 Zero Trust Architecture

Introduction to Task 2

Migrating from a legacy "flat network" to a segmented or Zero Trust architecture is the most difficult challenge facing modern CISOs.

We will critique a legacy network design and propose architectural improvements.

Task 2: Architectural Review

Timing: 50 minutes

A regional law firm has a single "flat" internal network (10.0.0.0/16). The web server, the employee laptops, the WiFi access points, and the central file server holding confidential case files are all on this same subnet.

  1. Explain the exact sequence of events that would occur if a receptionist's laptop was infected with a self-propagating ransomware worm on this network.
  2. Design a segmented architecture for this firm. Define at least three distinct network zones (e.g., DMZ, Internal, Guest WiFi) and outline the firewall rules between them.

Summary & Next Steps

  • Security is a holistic discipline. Fixing the technology does not matter if the processes are broken or the people are untrained.
  • The traditional network perimeter is dead. Modern architecture focuses on Identity and Zero Trust.
Next Week: Cyber-Physical Systems & Critical Infrastructure