Chapter 7 — Security architecture and engineering: data and telemetry
Lesson map
Lesson 07 published. Map, example, EX025.
flowchart TD
N0["Learning outcomes"]
N1["7.1 Sensitive data"]
N2["7.2 Useful telemetry"]
N3["7.3 Protecting logs"]
N4["Synthesis"]
N0 --> N1 --> N2 --> N3 --> N4
N4 --> EX["Worked example"]
EX --> Q["Exercise EX025"]
Logical drawing
flowchart LR
N0["Learning outcomes"]
N1["7.1 Sensitive data"]
N2["7.2 Useful telemetry"]
N3["7.3 Protecting logs"]
N4["Synthesis"]
N0 --> N1 --> N2 --> N3 --> N4 --> Q["EX025"]
[Learning outcomes]
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v
[7.1 Sensitive data]
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v
[7.2 Useful telemetry]
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v
[7.3 Protecting logs]
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v
[Synthesis]
|
v
[Worked example] --> [Exercise EX025]
Learning outcomes
You will (1) identify sensitive data in a practice; (2) choose telemetry worth collecting; (3) protect logs themselves.
7.1 Sensitive data
Nadia lists where patient data lives at Elmfield: the cloud practice system, X-ray images on the imaging server, printed treatment plans, referral letters in email and appointment reminders sent by text. Dental records are health data and need strong protection under data protection law. She notes that X-ray images carry patient names and dates of birth in their file headers. Knowing where sensitive data sits tells her which systems need the strongest access control, encryption and backup. She records each location in a short table with the system owner and the people who can access it.
7.2 Useful telemetry
Grace cannot watch everything. Nadia proposes collecting a small set of signals: sign-ins to PCs and the cloud practice system, administrator actions, firewall denials between segments, backup results and antivirus alerts. Each signal supports a question Grace may need to answer, such as who viewed a record or whether malware tried to reach the imaging server. Telemetry without a question to answer becomes noise. She asks the cloud vendor what audit logs they provide and how long they keep them.
7.3 Protecting logs
Logs can contain sensitive information and can be altered by an attacker covering tracks. Nadia recommends sending PC and firewall logs to a cloud log service that practice staff cannot modify, keeping them for one year, and restricting access to Grace and one deputy. She checks that clocks on all devices synchronise with a time server, so events can be ordered correctly. Daniel notes that logs are evidence, and evidence must be protected from both loss and tampering if it is to be trusted after an incident.
Worked example
Nadia maps patient data locations, selects five telemetry signals tied to questions and protects logs with central storage, retention and restricted access.
Synthetic case. Data locations and services are synthetic.
Errors and limits
Vendor audit logs may be limited. Central logging adds cost and a dependency.
Exercises
- EX025 — Image headers. What sensitive data do X-ray file headers carry? Rubric: 3 = patient names and dates of birth;; 2 = identifiers;; 1 = vague;; 0 = none.
- EX026 — Telemetry rule. Why tie each signal to a question? Rubric: 3 = telemetry without a question becomes noise;; 2 = purpose;; 1 = vague;; 0 = none.
- EX027 — Log location. Where should PC and firewall logs go? Rubric: 3 = a cloud log service staff cannot modify;; 2 = central;; 1 = local PC;; 0 = none.
- EX028 — Clock sync. Why synchronise device clocks? Rubric: 3 = so events can be ordered correctly;; 2 = ordering;; 1 = vague;; 0 = none.
Synthesis
Knowing where sensitive data lives and collecting purposeful, protected telemetry prepares a practice to detect and investigate.
Continue studying — chapter 07 of 18
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