Endpoint process context triage

# Endpoint process context triage

Read a small process tree and explain which relationships deserve a closer look without declaring that an executable is malware.

This is an original, fictional, offline exercise for an introductory security learner. It is independent practice, not copied coursework or a claim of professional experience. Completion and competence remain unassessed.

## Before you start

Allow **30-45 minutes**: 5 minutes reading, 10 inspecting and predicting, 10 checking and explaining, and 5-20 for a changed or independent case. You need Python 3.10+ (standard library only), a terminal and a text editor. Comfort opening files, reading a small table and basic evidence notes is enough; programming, administrator rights, a Linux installation and cloud accounts are unnecessary. Previous introductory network or Wireshark practice is useful but not required.

> **Vocabulary:** Parent: the process recorded as starting another process. Process tree: parent/child relationships. Signature: evidence about a signed file, not a promise of harmless behaviour. Triage: deciding what to inspect next. False positive: a signal with a benign explanation.

## Evidence and exact rules

The case JSON is the single authoritative input. Fixtures are guided.json, changed.json and challenge.json. All data is synthetic; artifacts is empty to avoid competing editable copies. Edit only a prepared run copy. The analyser is a pure calculation and never executes evidence text.

data.processes contains unique ID, parent ID (or null), image, role, location, signature evidence, a boolean documented-change note and an inert command string. Parents must be present and the tree must be acyclic. Roles are desktop/document/shell/service/utility; locations are system/program/user-temp; signatures are verified/unsigned/unknown. These labels are supplied evidence, not facts discovered from your computer.

A shell whose immediate parent is a document process, or execution in user-temp, gives prioritise-context-review when there is no documented approval. Any documented change gives documented-change-context. Otherwise unsigned/unknown evidence gives signature-context-incomplete; remaining rows give no-modelled-triage-trigger. A verified signature never cancels a contextual trigger. Rules are applied in that order. The exact labels belong in answers.json.

## Run the exercise

Open a terminal in this lab folder. Use your Python command (`python`, or `py -3` if that is how Python is installed). Commands below use `python` consistently.

```text
python lab.py cases
python lab.py prepare --scenario guided --out run/attempt-01
python lab.py show --case run/attempt-01/case.json
```

Read the evidence. In run/attempt-01/answers.json, fill each decision with an exact label from the rules; add an explanation and evidence references such as record IDs or configuration line numbers. In notes.txt, separate observation, interpretation, uncertainty, next check and help used. Save your prediction before opening the answer.

```text
python lab.py analyse --case run/attempt-01/case.json
python lab.py check --case run/attempt-01/case.json --answers run/attempt-01/answers.json
python lab.py prepare --scenario changed --out run/attempt-02
python lab.py prepare --scenario challenge --out run/attempt-03
python -m unittest -v test_lab.py
python lab.py verify
```

For changed/challenge use the corresponding attempt folder in show/analyse/check. prepare refuses an existing output folder. --out is relative to this lab and must be below run/; explicit input paths are relative to your terminal directory. analyse/show default to the guided fixture if --case is omitted. Exit 0 means command success or decision match; 1 means differences/incomplete written fields; 2 means invalid input or a filesystem problem. The checker verifies decision fields and the presence of writing, not the quality of reasoning. verify checks shipped examples, not learner mastery.

## Deliverable and limits

Keep case.json, answers.json and notes.txt together in the ignored run folder. Deliver a short handover: the question, your conclusion, two precise evidence references, one alternative explanation or limitation, and the next evidence you would request. State whether you used the worked example and whether you completed a fresh case unaided. Do not describe an automated match as assessment or professional experience.

A suspicious relationship is a review priority, not proof of malware; a verified signature is not proof of safety. This bounded tree omits memory, file contents, network activity and missing telemetry; no host was inspected.

Use WORKED-EXAMPLE.md after making a first prediction, and DRILLS.md for progressively less support. Do not use these rules as an operational security verdict or modify a real host as part of this exercise.

## Primary references

The following documentation supports the underlying concepts; the tiny schema and explicit teaching rules above are specific to this lab. Links were checked during authoring on 23 October 2026. Running the lab needs no internet connection.

- [Microsoft Sysmon event documentation](https://learn.microsoft.com/en-us/sysinternals/downloads/sysmon)

# Worked example: Endpoint process context triage

Try the guided case before reading this page. Use `python lab.py prepare --scenario guided --out run/worked-01` if you need a fresh ignored copy.

Start at p1, the desktop root, then trace p1 -> p2 -> p3. p2 is a document process and p3 is a shell. p3 therefore deserves context review even though its signature is verified and it runs from system. p4 is an unsigned utility in user-temp, a separate trigger. p1 and p2 have no modelled triggers; that is not a clean bill of health. The inert command text gives a collection lead, not something to run. Ask whether a helpdesk demonstration or approved macro explains p3, and request the executable hash and collection context for p4.

The reference decision fields for guided are:

```json
{
  "p1": "no-modelled-triage-trigger",
  "p2": "no-modelled-triage-trigger",
  "p3": "prioritise-context-review",
  "p4": "prioritise-context-review"
}
```

Now open `python lab.py analyse --case run/worked-01/case.json` and compare observations, not only labels. Record one difference between your first prediction and the reference. If there was no difference, explain the rule that produced each decision rather than copying the label.

Handover prompt: explain what this evidence establishes, cite its exact IDs or lines, give a plausible alternative or remaining uncertainty, and name the smallest next check. Record any help used. A correct label by itself is not evidence of independent understanding.

# Drills: Endpoint process context triage

## Guided practice

Prepare guided in a fresh run folder, read the README rules, and make a prediction for every decision ID. Use WORKED-EXAMPLE.md only after saving that prediction. Correct your explanation in a different paragraph so the original reasoning remains visible.

## Prompts only

Close the worked example and use these questions to reconsider the evidence:

- Which parent-child edge produces a trigger even with a verified signature?
- What additional evidence would distinguish an approved demonstration from unexplained activity?

## Independent attempt

Prepare challenge in a fresh folder. Keep reference outputs, worked example and analyse closed until you have saved answers.json plus a five-sentence handover in notes.txt. Include the observation, interpretation, an alternative, uncertainty and next check. Use the README for syntax if needed and record that help. Afterwards run analyse/check and have a person inspect the explanation. Independent completion is unassessed unless someone actually reviews it.

## Changed case

Prepare changed. Predict which conclusions change and which do not. Explain the changed evidence before checking:

- Why does a documented demonstration change p3 while its parent and signature stay the same?
- Why does unsigned p4 still need signature context after moving out of user-temp?

Small edit drill: In a copied guided case, change p3.approved_change from false to true, predict the one changed decision, then analyse. Do not edit a fixture or execute its command text.

## Teach-back

Explain why neither a suspicious process tree nor a verified signature establishes whether a program is malicious. Use exact record IDs from your attempt. A partner should ask one counterexample rather than accepting a memorised label. Record the question and your response.

## Later recall

After 24-72 hours, reopen only your own notes and a fresh case. Write the central rule from memory, identify one boundary or missing-evidence condition and predict the result. Then check the documentation and record what you forgot. Do not count rereading an answer as an independent attempt.

## Handover

Keep the copied case, completed worksheet and notes together. State the scope, conclusion, two evidence references, unresolved uncertainty and requested next check. Include help used and whether someone assessed the reasoning. Do not claim experience beyond this fictional exercise.