Chapter 11 — Security architecture and engineering: verification
Lesson map
Lesson 11 published. Map, example, EX041.
flowchart TD
N0["Learning outcomes"]
N1["11.1 After deployment"]
N2["11.2 Testing from each segment"]
N3["11.3 Recording results"]
N4["Synthesis"]
N0 --> N1 --> N2 --> N3 --> N4
N4 --> EX["Worked example"]
EX --> Q["Exercise EX041"]
Logical drawing
flowchart LR
N0["Learning outcomes"]
N1["11.1 After deployment"]
N2["11.2 Testing from each segment"]
N3["11.3 Recording results"]
N4["Synthesis"]
N0 --> N1 --> N2 --> N3 --> N4 --> Q["EX041"]
[Learning outcomes]
|
v
[11.1 After deployment]
|
v
[11.2 Testing from each segment]
|
v
[11.3 Recording results]
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v
[Synthesis]
|
v
[Worked example] --> [Exercise EX041]
Learning outcomes
You will (1) verify controls after deployment; (2) test from each segment; (3) record verification results.
11.1 After deployment
Grace applies the new rules at Elmfield on a Sunday. On Monday morning, Nadia verifies that the deployed configuration matches the design. She does not rely on the router's configuration screen alone, because what is configured and what actually happens can differ. She plans tests from each segment using a laptop she can move between ports and networks, with Grace's written approval. Verification checks the real behaviour that patients and staff will experience, not just the intent. She also books an hour with Grace to review the results together.
11.2 Testing from each segment
From the surgery segment, Nadia opens the X-ray viewer successfully and confirms she cannot reach card terminals. From reception, she confirms the cloud practice system works and the imaging server is unreachable. From the guest network, she reaches the internet but no internal devices. From the payment segment, she checks with the provider's test tool that terminals still process transactions. One test fails: the surgery printer cannot be reached from surgery PCs because it was placed in the reception segment. Grace moves it.
11.3 Recording results
Nadia records each test: date, segment, target, expected result, actual result and tester. The record shows the printer failure and its fix, followed by a passing retest. She adds the test list to Linden's change procedure so the same tests run after any future change at any practice. Recorded verification is evidence for auditors and the payment provider, and it shortens troubleshooting later because the team knows which flows worked on which date. The records are kept in a shared folder with the rule list and diagrams, so anyone investigating a later problem can compare against them.
Worked example
Nadia verifies Elmfield's segmentation by testing from four segments, finds a misplaced printer and records results for reuse.
Synthetic case. Tests and devices are synthetic.
Errors and limits
Tests at one time do not prove future behaviour. Moving a laptop between segments needs care.
Exercises
- EX041 — Why not the screen. Why not rely on the router's configuration screen? Rubric: 3 = configured and actual behaviour can differ;; 2 = behaviour;; 1 = vague;; 0 = none.
- EX042 — Guest test. What did the guest network test confirm? Rubric: 3 = internet only, no internal devices;; 2 = internet only;; 1 = vague;; 0 = none.
- EX043 — Failed test. Which test failed and why? Rubric: 3 = surgery printer unreachable; placed in reception segment;; 2 = printer;; 1 = vague;; 0 = none.
- EX044 — Reuse. How will the tests be reused? Rubric: 3 = added to the change procedure for future changes;; 2 = change procedure;; 1 = vague;; 0 = none.
Synthesis
Verification from every segment, with recorded results, confirms that controls behave as designed.
Continue studying — chapter 11 of 18
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