Chapter 33 — Information security: safety and resilience | Engineering Information security

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Chapter 33 — Information security: safety and resilience

Lesson map

Lesson 33 published. Map, example, EX097.

flowchart TD
  N0["Learning outcomes"]
  N1["33.1 Resilience"]
  N2["33.2 Manual fallbacks"]
  N3["33.3 Exercises"]
  N4["33.4 Safety and integrity"]
  N0 --> N1 --> N2 --> N3 --> N4
  N4 --> EX["Worked example"]
  EX --> Q["Exercise EX097"]

Logical drawing

flowchart LR
  N0["Learning outcomes"]
  N1["33.1 Resilience"]
  N2["33.2 Manual fallbacks"]
  N3["33.3 Exercises"]
  N4["33.4 Safety and integrity"]
  N0 --> N1 --> N2 --> N3 --> N4 --> Q["EX097"]

[Learning outcomes]
    |
    v
[33.1 Resilience]
    |
    v
[33.2 Manual fallbacks]
    |
    v
[33.3 Exercises]
    |
    v
[33.4 Safety and integrity]
    |
    v
[Worked example] --> [Exercise EX097]

Learning outcomes

You will (1) plan for continued operation during incidents; (2) design manual fallbacks; (3) exercise resilience plans.

33.1 Resilience

Resilience means continuing essential work during disruption and recovering quickly. Lindiwe asks Saltmarsh's operations managers what must continue if systems fail: refrigerated medicine deliveries, payroll and customer communication. She builds a list of essential services with the systems each depends on. Prof. Hale explains that resilience planning starts from services the business cannot stop, not from systems, because several systems often support one service and one system can support several. Lindiwe records the services in a table with their dependent systems and the longest tolerable outage for each, as agreed with the managers.

33.2 Manual fallbacks

If dispatch fails, depots cannot print delivery lists. Lindiwe works with depot supervisors to design a manual fallback: a nightly printed list of the next day's deliveries kept in a locked cabinet, and paper confirmation forms entered later. For refrigerated loads, drivers carry independent temperature loggers that do not depend on the network. She learns that the best fallbacks are simple, practised and independent of the systems they replace. The supervisors test the printed list and paper forms during one quiet Sunday shift, and drivers find the forms easy to complete.

33.3 Exercises

Plans that are never exercised often fail. Lindiwe organises a tabletop exercise: ransomware has encrypted the dispatch server on a Monday morning. Managers walk through their actions. They discover that nobody knows where the printed lists are kept at one depot and that the incident contact list contains two people who have left. Prof. Hale notes that finding such problems in an exercise is exactly the purpose, and that every exercise should produce a short list of improvements. The improvements list has seven items.

33.4 Safety and integrity

Lindiwe returns to the safety concern from her first year: temperature records for medicines. During a cyber incident, records might be lost or altered. She recommends that drivers' independent loggers be read at delivery and their results kept separately, so evidence of safe temperatures survives a system compromise. The fleet manager accepts the recommendation. She learns that resilience for safety-related data needs independent evidence, not just backups of the same system. Lindiwe adds this requirement to the resilience plan, and the fleet team includes it in driver training.

Worked example

Lindiwe identifies essential services, designs printed and independent fallbacks, runs a ransomware tabletop exercise that exposes outdated contacts and protects temperature evidence independently.

Synthetic case. Plans and exercises are synthetic.

Errors and limits

A resilience plan that has never been exercised usually contains outdated details.

Exercises

EX097 — Essential services. Name one essential service identified. Rubric: 3 = refrigerated medicine deliveries;; 2 = one;; 1 = vague;; 0 = none.
EX098 — Exercise discovery. What did the exercise reveal? Rubric: 3 = missing printed lists location and outdated contacts;; 2 = partly correct;; 1 = vague;; 0 = none.
EX099 — Temperature evidence. How is temperature evidence protected? Rubric: 3 = independent loggers read at delivery;; 2 = partly correct;; 1 = vague;; 0 = none.

Continue studying — lesson 33 (chapter 33 of 50)

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