Chapter 8 — Computer architecture

Lesson map

Lesson 08 published. Map, example, EX022.

flowchart TD
  N0["Learning outcomes"]
  N1["8.1 Assets from architecture"]
  N2["8.2 Firmware and trust"]
  N3["8.3 Supply chain"]
  N4["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4
  N4 --> EX["Worked example"]
  EX --> Q["Exercise EX022"]

Logical drawing

flowchart LR
  N0["Learning outcomes"]
  N1["8.1 Assets from architecture"]
  N2["8.2 Firmware and trust"]
  N3["8.3 Supply chain"]
  N4["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4 --> Q["EX022"]

[Learning outcomes]
    |
    v
[8.1 Assets from architecture]
    |
    v
[8.2 Firmware and trust]
    |
    v
[8.3 Supply chain]
    |
    v
[Synthesis]
    |
    v
[Worked example] --> [Exercise EX022]

Learning outcomes

You will (1) map system components to governance assets; (2) understand where controls act in hardware and firmware; (3) include supply chain in risk scope.

8.1 Assets from architecture

Nadia studies how computers are built from processors, memory, storage and input-output devices, all controlled by firmware and operating systems. For governance, she learns to treat these layers as assets with owners. An asset inventory, required by ISO/IEC 27001:2022 through its Annex A controls, must list not only servers and laptops but also the control-system devices at substations. Without knowing what exists, Ardwell cannot assess risk or demonstrate that controls apply to everything in scope. She lists each layer with its owner and records which team updates the record when equipment changes.

8.2 Firmware and trust

Firmware runs before the operating system and is rarely updated. Nadia learns that if firmware is compromised, operating system controls can be bypassed. She adds firmware version tracking to Ardwell's asset records and proposes that procurement require vendors to provide signed updates. Prof. Brenner notes that governance often stops at the operating system because firmware is invisible, yet NIST SP 800-53 Rev. 5 includes controls on system and firmware integrity, which give a basis for asking vendors the right questions. She drafts the clause.

8.3 Supply chain

Every hardware component arrives through a supply chain. Nadia lists Ardwell's suppliers for control-system devices and notes which provide security updates and for how long. Two older devices are past their vendor's support period, so new vulnerabilities will not be fixed. She records this as a risk with options: replace, isolate or accept with compensating monitoring. She learns that supply chain risk management is part of the Govern function in NIST CSF 2.0, linking architecture knowledge to board-level oversight. She adds it to the register.

Worked example

Nadia adds control-system devices and firmware to the inventory, requires signed updates and records unsupported devices as a risk.

Synthetic case. Devices and suppliers are synthetic; standards cited are real.

Errors and limits

Inventories go stale. Vendor support dates change.

Exercises

• EX022 — Inventory scope. What must Ardwell's asset inventory include beyond servers and laptops?
  Show marking criteria

  Rubric: 3 = control-system devices at substations;; 2 = OT devices;; 1 = vague;; 0 = none.
• EX023 — Firmware risk. Why does compromised firmware matter?
  Show marking criteria

  Rubric: 3 = it can bypass operating system controls;; 2 = bypass;; 1 = vague;; 0 = none.
• EX024 — Unsupported options. Which options exist for the two unsupported devices?
  Show marking criteria

  Rubric: 3 = replace, isolate or accept with monitoring;; 2 = three options;; 1 = vague;; 0 = none.

Synthesis

Architecture knowledge extends governance to firmware, devices and the supply chain.

Continue studying — chapter 08 of 50

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