Mission brief · C-366

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

Files on a production share were overwritten and deleted rather than encrypted, so there is no note and nothing to pay for. Establish the tool and the scope, judge it against the retention job that deletes expired files, and get the share back from a recovery point.

Incident timeline

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

−25mAn admin account signs in to the file server out of hoursIdentityT1078.002
−20mA secure-delete utility is dropped into a temporary folderEDRT1105
−12mThe retention job deletes its usual batch of expired filesSIEMordinary activity
alertThousands of files are overwritten then removed from one shareEDRT1485
+14mShadow copies on the server are removed as wellEDRT1490

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 tool used and the share it was pointed at.
Why this step: The learner named the tool used and the share it was pointed at. It carries 20 points on the investigation dimension.
4. Destruction was told apart from the scheduled retention deletions.
Why this step: Destruction was told apart from the scheduled retention deletions. 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 share was restored from a recovery point taken before the deletions.
Why this step: The share was restored from a recovery point taken before the deletions. 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.