Cybrary ForgeCYBRARY / FORGE
Curriculum
N-403·Cross-platform·50 min

Rebuild the Northwind rule base from the wire Start this lab

Three firewall migrations later, nobody can say which rules exist, and change control will not approve the next one without evidence. You get an ordinary corporate seat, no console and no exported config. Probe each zone crossing until the rule base identifies itself by number.

Mission brief · N-403

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

Why this matters

Firewall documentation rots faster than firewall configuration. Analysts who can only describe a rule base from a wiki cannot tell an incident commander whether a path was possible, and change reviewers cannot approve a migration on that basis. Probing from a normal seat produces evidence that stays true regardless of what the documentation claims.

Concepts

The routing table anchors everything you will claim

Before any probe means anything you need to know which zone you are speaking from. The connected network and the default gateway define the source of every test, and a report that omits them cannot be reproduced by the person reviewing it.

Permits deserve numbers as much as denies do

It is tempting to record only what is blocked, but a migration breaks on the permits nobody wrote down. A verbose probe that succeeds names the rule that carried it, and that number is what survives into the change record.

An absent permit is a finding, expressed by the catch-all

Where no specific rule exists, the default deny at the bottom of the base is what enforces the boundary. Naming that catch-all is how you distinguish a deliberate boundary from an accidental one, and it tells a reviewer the base terminates safely.

Probing is an authorized activity, not an assumed one

Scanning production from a corporate seat happens under a change record. The habit of tying discovery activity to an authorization is what separates an audit exercise from an incident of its own.

Objectives graded

  • Read a routing table and turn it into an accurate picture of the local zone
  • Evidence permits and denies by rule number using verbose scanning from a normal seat
  • Produce a rule-base map that survives review without console access

Live walkthrough

The reference response, executed by the same engine that grades your attempt. Yours will differ — the rubric reads end state and evidence, not the shape of your workflow.

  1. 1.Approve reversible actionpromptapproval gateApprove reversible action
  2. 2.Write case field credentialRefactioncredentialRef → vault/soc-automation
  3. 3.Attach evidence: case/soar-n-403/evidenceactionThe learner attached at least one linkable piece of evidence to the case.
  4. 4.Write case field closureNoteactionclosureNote → written
  5. 5.Attach evidence: range/hst-nw-net31/sessionactionThe rule base was evidenced from probes rather than transcribed from memory.
  6. 6.Write case field localCidractionlocalCidr → 10.42.31.0/24
  7. 7.Write case field defaultGatewayactiondefaultGateway → 10.42.31.1
  8. 8.Write case field adAllowRuleactionadAllowRule → 105
  9. 9.Write case field proxyAllowRuleactionproxyAllowRule → 115
  10. 10.Write case field lateralDenyRuleactionlateralDenyRule → 125
  11. 11.Write case field dmzDenyRuleactiondmzDenyRule → 900
  12. 12.Attach evidence: case/soar-n-403/timelineactionA rule-base map was filed, which is the deliverable change control actually asked for.
  13. 13.Write case field seatRamGbactionseatRamGb → 16
  14. 14.Write case field seatDiskGbactionseatDiskGb → 512

Gate approved — 100%

19 of 19 rubric rules hold.

Gate denied — 93%

Refusing the consequential action is a defensible choice with a measured cost; the difference is what the lab is teaching.

  • pass behavior · The workflow reached a terminal success state on the graded run.
  • pass safety · A reversible action passed through a human approval gate.
  • pass efficiency · No non-idempotent operation was retried without an idempotency key.
  • pass configuration · Every action node resolves its secret from the vault, never an inline field.
  • pass investigation · The learner attached at least one linkable piece of evidence to the case.
  • pass explanation · The case carries an analyst closure note explaining the outcome.
  • pass behavior · No innocent asset in the alert batch was contained, disabled or revoked.
  • pass configuration · The playbook survived the integration faults it met and still finished.
  • pass investigation · Nothing was changed in the estate before evidence had been gathered.
  • pass investigation · The rule base was evidenced from probes rather than transcribed from memory.
  • pass investigation · The connected subnet was read from the routing table.
  • pass investigation · The default gateway was read from the routing table, which anchors every other hop.
  • pass investigation · A permit was evidenced by number, so the AD path is documented rather than presumed.
  • pass behavior · The egress path is documented by the rule that permits it, not by the fact the browser works.
  • pass behavior · Endpoint isolation inside the VLAN is proven by a numbered deny.
  • pass behavior · The absence of a user-to-DMZ permit was proven, and the catch-all that enforces it named.
  • pass explanation · A rule-base map was filed, which is the deliverable change control actually asked for.
  • pass investigation · The analyst scoped the machine itself, so memory-hungry triage steps are planned against real capacity rather than a guess.
  • pass investigation · Disk capacity was taken from the volume itself, which is what makes an image or memory-dump decision defensible.

MITRE ATT&CK coverage

The same enumeration an intruder performs on arrival - what subnet am I in, who routes, what may I reach - run deliberately, so each permit and deny in the perimeter rule base is evidenced by number.

TechniqueNameTactic
T1046Network Service DiscoveryDiscovery
T1016System Network Configuration DiscoveryDiscovery
T1018Remote System DiscoveryDiscovery
T1049System Network Connections DiscoveryDiscovery

What each rubric rule proves

  • The workflow reached a terminal success state on the graded run.

    behavior · weight 20 · T1046 Network Service Discovery (Discovery)

  • A reversible action passed through a human approval gate.

    safety · weight 15 · T1046 Network Service Discovery (Discovery)

  • No non-idempotent operation was retried without an idempotency key.

    efficiency · weight 10 · T1046 Network Service Discovery (Discovery)

  • Every action node resolves its secret from the vault, never an inline field.

    configuration · weight 10 · T1016 System Network Configuration Discovery (Discovery)

  • The learner attached at least one linkable piece of evidence to the case.

    investigation · weight 10 · T1018 Remote System Discovery (Discovery)

  • The case carries an analyst closure note explaining the outcome.

    explanation · weight 10 · T1016 System Network Configuration Discovery (Discovery)

  • No innocent asset in the alert batch was contained, disabled or revoked.

    behavior · weight 15 · T1046 Network Service Discovery (Discovery)

  • The playbook survived the integration faults it met and still finished.

    configuration · weight 15 · T1018 Remote System Discovery (Discovery)

  • Nothing was changed in the estate before evidence had been gathered.

    investigation · weight 10 · T1049 System Network Connections Discovery (Discovery)

  • The rule base was evidenced from probes rather than transcribed from memory.

    investigation · weight 10 · T1018 Remote System Discovery (Discovery)

  • The connected subnet was read from the routing table.

    investigation · weight 10 · T1016 System Network Configuration Discovery (Discovery)

  • The default gateway was read from the routing table, which anchors every other hop.

    investigation · weight 10 · T1016 System Network Configuration Discovery (Discovery)

  • A permit was evidenced by number, so the AD path is documented rather than presumed.

    investigation · weight 10 · T1018 Remote System Discovery (Discovery)

  • The egress path is documented by the rule that permits it, not by the fact the browser works.

    behavior · weight 10 · T1049 System Network Connections Discovery (Discovery)

  • Endpoint isolation inside the VLAN is proven by a numbered deny.

    behavior · weight 15 · T1046 Network Service Discovery (Discovery)

  • The absence of a user-to-DMZ permit was proven, and the catch-all that enforces it named.

    behavior · weight 15 · T1046 Network Service Discovery (Discovery)

  • A rule-base map was filed, which is the deliverable change control actually asked for.

    explanation · weight 10 · T1016 System Network Configuration Discovery (Discovery)

  • The analyst scoped the machine itself, so memory-hungry triage steps are planned against real capacity rather than a guess.

    investigation · weight 3

  • Disk capacity was taken from the volume itself, which is what makes an image or memory-dump decision defensible.

    investigation · weight 3

Common mistakes

  • Recording that something 'works' without the rule number that made it work.
  • Reading the rule base from an exported config instead of proving it from the seat under review.
  • Forgetting that intra-VLAN traffic is switched, so only explicit rules apply between endpoints.
  • Leaving out the connected subnet and gateway, making the whole set of probes unreproducible.

Same idea, three vendors

Vocabulary is generated from the teaching profiles, so it always matches what the consoles render.

ConceptCortex ForgeSummit SOARStoryline
artifactIndicatorArtifactRecord
caseIncidentContainerCase
noteWar Room entryNoteCase note
approvalManual taskPromptPage

Where does this value come from?

The same reference to an enrichment node's verdict, written three ways:

  • Cortex Forge: ${enrich-sender.verdict}
  • Summit SOAR: enrich-sender.verdict
  • Storyline: <<enrich-sender.verdict>>

The same concepts in shipping products

The consoles you practice in use teaching names. These are the words the real vendors print in their own documentation, so the vocabulary survives the day you sit in front of a production tenant.

ConceptCortex XSOARXSOAR 8.xSplunk SOARSplunk SOAR 6.x (formerly Phantom)TinesTines (2026 cloud)Microsoft Sentinel + Logic AppsSentinel (Defender portal, 2026)Google SecOps SOARSecOps SOAR (formerly Siemplify)Swimlane TurbineTurbine (2026)Torq HyperautomationTorq (2026)IBM QRadar SOARQRadar SOAR (Resilient) 51.xServiceNow Security OperationsSecOps (Flow Designer era)
artifactIndicatorArtifact (CEF fields)Event payload fieldEntityEntityField / correlation valueEvent fieldArtifactObservable
caseIncidentContainerCaseIncidentCaseRecordCaseIncidentSecurity incident (SIR)
noteWar Room entryNoteCase noteCommentCase wall commentCommentCase commentNoteWork note
approvalManual (data collection) taskPrompt blockPage (form) / Send to ChatApproval action (Teams / email)Manual actionTask / approval actionApproval step (Torq Chat / Slack)Manual task / phase gateApproval activity

What transfers

Security groups, network policies and NACLs all answer the same interrogation: from this source, to that destination, on this port, which statement decided the outcome? The tool changes; the evidence standard does not.