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SYS-C0234 · Reference & Lookup

Writing Blameless Postmortems

Write a blameless postmortem of one incident, and do not include an attack procedure.

Updated 25 October 2026 · How-To

This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.

What this hour is for

The template drafts a timeline, the impact, and one change that would have made the incident smaller. It does not investigate a host and it does not describe how to break in.

Name the service and the time. Blame stays off the page. A person's name is not the cause. Do not include exploit steps, payment steps, or a wipe.

192.0.2.10/24 and example.com are documentation. They stay in the note.

The change you can finish

Apply nothing while you are writing the note. When the lab window opens, it is one change on the host named in the ticket. Read the draft, then the host, then decide.

Rollback is the file, the package version, or the snapshot you saved first. You do not invent a rollback after the only copy is gone.

  1. Write the time and the service.
  2. Write what users saw.
  3. Write one corrective change.
  4. Leave exploit steps out.
  5. Stop.

Mistakes that outlive the command

Writing Blameless Postmortems goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.

Decisions to write down

One decision for Writing Blameless Postmortems: The timeline is written. The cause is a condition, not a person. No exploit steps are present. And one corrective change is written.

Checks before you call it done

Confirm this before you call the change done: The service is written. The time is written. The corrective change is written. No exploit steps are present. And no person is the cause. If one of those fails, stop.

# Blameless.
# No exploit steps.
# One corrective change.
# This page does not describe an intrusion.

Before you leave the host

Writing Blameless Postmortems ends when the hostname in the prompt matches the hostname in the ticket. If it does not, you are on the wrong host. Stop. A command that succeeded on the wrong host is not progress.

The draft stays a draft until a person has read the names in it. A generator does not log into the host and does not know which disk is empty. You delete a line that names a host, a path, or an account you did not write down.

192.0.2.10/24, gateway 192.0.2.1, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. example.com is a documentation name. They belong in the note. They are not values you leave on a host because a draft included them.

prompt-for-this is a reminder that a secret is missing. It is not a password, a key, or a token you save in the ticket or in git. The real secret stays in the password store.

One change is the window. If two things move and the result is wrong, you will not know which one did it. The next change waits for its own page.

If the same step fails twice, stop for the day. The failure is the result. Adding a forum command beside a half-applied change produces a host nobody can rebuild. Restore the copy you took first.

A second person reads the hostname and the change aloud. If they cannot find them in the ticket, the note is not done. Silence is not agreement. Then leave the host alone.

This page is a planning guide. It is not a vendor manual, not an official standard, and not permission to touch a host you do not administer. You do not disable a firewall, AppArmor, or SELinux to make a check pass.

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