Mission 13 · Practice the response
The update that reopened a door
Treat updates as changes to a security boundary.
A maintenance update installed new packages. Some package permissions and defaults may have changed. Installation needed temporary internet access.
Maintenance reminder
“The software is updated. Are we finished?”
The decision
Choose the complete maintenance habit.
- Snapshot, controlled update, restore restrictions, and test again
Review changed settings and refresh the integrity baseline after legitimate changes. - Leave the install network open for convenience
The next update will be easier. - Trust the previous tests forever
They passed before the software changed.
Reveal the explanation
An update is not finished until the protections are restored and tested. A green test from last week describes last week’s system.
Security is a maintained process, not a setup you finish once.- Updates can restore privileged program permissions or introduce new options with unsuitable defaults.
- Containers use the host kernel, so an installed kernel patch needs a reboot to take effect.
- A fresh integrity baseline distinguishes legitimate maintenance from unexplained later changes.
Integrity baseline
A saved record of expected file contents or hashes, used to detect later changes.