Mission brief · C-357

Tier 3 analyst on the incident response bench

Tier 3 — deep host and forensics

Business important

Track default

You are acting as

the break-glass IR account `svc-ir`, checked out of the vault for this incident — never the compromised identity

How you got here

The detection fired in the EDR console. You opened a live-response session from that detection, so your shell rides the EDR agent channel — containing the host will *not* cut you off, which is exactly why you contain from here rather than over SSH.

Your access

EDR console (detections + live response)
Endpoint detection & response
- Read the detection and process tree
- Look up host criticality, owner and VIP flags
- Open a live-response session on the host
- Contain the host over the agent channel
- Not yours: Disable user accounts (that's the identity team)
- Not yours: Delete evidence
Live-response shell on the affected host
Host shell session
- Read the filesystem, logs and running state
- Collect a triage package
- Not yours: Reboot or reimage without owner approval

What's at stake

The affected host

Owner: The system's business owner, named on the asset record

Containing a host you haven't identified can stop revenue. Check criticality and owner before you isolate anything.

Rules of engagement

You may act alone

Investigate from the live-response session
Collect evidence and triage packages
Contain a standard-criticality host

Ask a human first

Containing a mission-critical host — asset owner and on-call manager first
Disabling a user identity — identity team, and HR/legal if it looks like an insider

How much help do you want?

Objectives stay open and every step explains why it matters before it tells you what to run. Hints are free.

Graded case walkthrough

Open a lab as a live case and advance it one node at a time. The score beside each step is the lab rubric re-evaluated against what the engine actually did.

Lab

A finance clerk opened a macro-enabled invoice from an external sender and clicked through the warning. Name the file, judge it against the invoices this team receives every day, and clear the same message from every other mailbox it reached.

Incident timeline

Relative to the moment the alert fired. One of these beats is ordinary activity.

−34mA supplier-styled mail with a macro-enabled attachment reaches 14 mailboxesMail gatewayT1566.001
−18mThe invoice intake service opens twelve ordinary supplier invoicesMail gatewayordinary activity
−3mThe clerk opens the attachment and enables contentEDRT1204.002
alertThe document process starts a shell and the alert firesEDRT1059.001
+6mThe same message is still sitting unread in eleven other mailboxesMail gatewayT1566.001

Range guide

Guided

Every step explains why it matters before it tells you what to do. Reasoning is free in guided mode.

Prove it

1. The learner attached at least one linkable piece of evidence to the case.
Why this step: The learner attached at least one linkable piece of evidence to the case. It carries 10 points on the investigation dimension.
2. Nothing was changed in the estate before evidence had been gathered.
Why this step: Nothing was changed in the estate before evidence had been gathered. It carries 10 points on the investigation dimension.
3. The learner named the attachment that was opened, not the sending domain.
Why this step: The learner named the attachment that was opened, not the sending domain. It carries 20 points on the investigation dimension.
4. The attachment was judged apart from the genuine invoices arriving alongside it.
Why this step: The attachment was judged apart from the genuine invoices arriving alongside it. It carries 15 points on the investigation dimension.

Decide and act

1. The workflow reached a terminal success state on the graded run.
Why this step: The workflow reached a terminal success state on the graded run. It carries 20 points on the behavior dimension.
2. A consequential action passed through a human approval gate.
Why this step: A consequential action passed through a human approval gate. It carries 15 points on the safety dimension.
3. No non-idempotent operation was retried without an idempotency key.
Why this step: No non-idempotent operation was retried without an idempotency key. It carries 10 points on the efficiency dimension.
4. Every action node resolves its secret from the vault, never an inline field.
Why this step: Every action node resolves its secret from the vault, never an inline field. It carries 10 points on the configuration dimension.
5. No innocent asset in the alert batch was contained, disabled or revoked.
Why this step: No innocent asset in the alert batch was contained, disabled or revoked. It carries 15 points on the behavior dimension.
6. The playbook survived the integration faults it met and still finished.
Why this step: The playbook survived the integration faults it met and still finished. It carries 15 points on the configuration dimension.
7. The message was removed from every mailbox it reached, not just this one.
Why this step: The message was removed from every mailbox it reached, not just this one. It carries 20 points on the behavior dimension.

Write it up

1. The case carries an analyst closure note explaining the outcome.
Why this step: The case carries an analyst closure note explaining the outcome. It carries 10 points on the explanation dimension.

Your cases

No cases opened yet.