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OT security lab · Level 5 of 8

Spot the intruder: the events that matter in a day's log

Level 5 of 8 in the OT security lab: a free OT security exercise at Intermediate level. Read a day of plant logs. Flag the few events that matter, say why, and leave the routine and approved ones alone.

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Free · no download. Your work is saved on this device. Updated 18 Oct 2026.

3D view of the Spot the intruder: the events that matter in a day's log level in the OT security lab
Spot the intruder: the events that matter in a day's log

The brief

Client
Wexley Cold Stores
Site
Cold store control room, Wexley
Work order
WO-OTS-105
Task code
OTS-05
Difficulty
Intermediate
Type of work
Monitoring

Read a day of plant logs. Flag the few events that matter, say why, and leave the routine and approved ones alone.

Skills you practise

  • Reading plant logs
  • Telling normal from suspicious
  • Change tickets and approvals
  • Triage

What the test checks

The acceptance test marks the skills this level practises.

  • Reading plant logs
  • Telling normal from suspicious
  • Change tickets and approvals
  • Triage

In this lab

  • Purdue levels, zones and conduits
  • Firewall rules, remote access and logs
  • Patch plans, backups and an incident drill

Levels in the OT security lab

Previous: Remote access: the vendor comes in through the DMZNext: Patch or protect: choose within the maintenance window

  1. Map the plant network: put every device on its level
  2. Zones and conduits: split a flat network
  3. Firewall rules: the minimum, then deny by default
  4. Remote access: the vendor comes in through the DMZ
  5. Spot the intruder: the events that matter in a day's log
  6. Patch or protect: choose within the maintenance window
  7. Backup and recovery: known-good copies and a proved restore
  8. Incident drill: a simulated note on an operator screen

Part of the OT security lab

Map a plant network, split it into zones, write the firewall rules, read the logs and run the response drill.

About the OT security lab

Feeds these internships: SCADA and HMI.