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Technical · Chapter 6 · English

Chapter 6 — Accounts and passwords on HMIs and engineering tools

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Chapter 6 — Accounts and passwords on HMIs and engineering tools

Lesson map

Lesson 06 published. Map, example, EX021.

flowchart TD
  N0["Learning outcomes"]
  N1["6.1 Shared accounts"]
  N2["6.2 Default passwords"]
  N3["6.3 Privileged accounts"]
  N4["6.4 Practical rules"]
  N5["6.5 When a password leaks"]
  N6["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> N6
  N6 --> EX["Worked example"]
  EX --> Q["Exercise EX021"]

Logical drawing

flowchart LR
  N0["Learning outcomes"]
  N1["6.1 Shared accounts"]
  N2["6.2 Default passwords"]
  N3["6.3 Privileged accounts"]
  N4["6.4 Practical rules"]
  N5["6.5 When a password leaks"]
  N6["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> N6 --> Q["EX021"]

[Learning outcomes]
    |
    v
[6.1 Shared accounts]
    |
    v
[6.2 Default passwords]
    |
    v
[6.3 Privileged accounts]
    |
    v
[6.4 Practical rules]
    |
    v
[6.5 When a password leaks]
    |
    v
[Synthesis]
    |
    v
[Worked example] --> [Exercise EX021]

Learning outcomes

You will (1) explain the risks of shared and default accounts; (2) apply simple account practices that work on a shift floor; and (3) handle a forgotten or leaked password correctly.

6.1 Shared accounts

Many HMIs ship with one "operator" account used by every shift. Then logs say "operator did it" and nobody knows who. Where the system supports it, give each person their own account; where it does not, record who was on shift and keep the shared password known only to the crew.

At HPFL the admin account on HMI-1 was used by operators to change wrapper speed, as Chapter 9 shows, which made the change hard to trace. Named accounts, or at least a shift log of who held the shared password, would have shown the person at once.

6.2 Default passwords

Default credentials are published in manuals, so anyone can look them up. ETSI EN 303 645 makes "no universal default passwords" its first provision for consumer IoT, and the same idea applies to plant devices: change defaults before a device goes into service.

At HPFL, check defaults on every new device before it joins the line network, including the vision camera and IoT sensors. Record in the register that the default was changed and when. If a device cannot change its default, report it so the owner can decide on other controls.

6.3 Privileged accounts

Admin accounts on HMI-1 and the engineering software can change screens, users and logic. They are used only for planned work, by named people, and their use is reviewed. They are not the everyday login.

At HPFL the admin password on HMI-1 was found on a sticky note on the panel, which shows how quickly privileged access spreads when it is used for everyday tasks. Review admin logins regularly against planned work, and remove admin rights from people whose roles no longer need them.

6.4 Practical rules

Use passphrases that are long but typeable with gloves; do not write passwords on the panel; lock the screen or log out when leaving; never share a password over the radio or by text.

These rules suit a shift floor where people wear gloves, share panels and work under time pressure. If a rule cannot be followed in practice, report that rather than quietly ignoring it; the owner may find a better way, such as a badge-based login. Review the rules with each new shift team.

6.5 When a password leaks

Report it, then the owner changes it at a time that will not disturb the line. Look at recent logins for that account (Chapter 9).

At HPFL, when Tomás found the admin password on a sticky note, the controls engineer changed it at the next planned stop and checked the login log for unexpected admin sessions. Record the leak, the change and the review in one report. Look for logins at odd hours or from unexpected places, and for setpoint changes that nobody can explain. Tell the shift team when the new password is in use.

Worked example (synthetic HPFL)

Tomás notices a sticky note on HMI-1 reading "admin / Harbor2024". He photographs it as evidence, removes it, tells the supervisor and the controls engineer, and writes a short report.

Synthetic case — HPFL. The note and password are invented.

Errors and limits

Some old HMIs cannot hold individual accounts; compensate with shift logs and physical control. Changing a password on a running system can lock out operators if done carelessly.

Exercises

Synthesis

Named accounts, changed defaults and limited admin use make actions traceable and harder to abuse.

Continue studying — chapter 06 of 18

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