Week 12: Hardening Is Controlled Change

Hardening means reducing unnecessary exposure and making system behavior more deliberate. It does not mean changing every setting that sounds secure.

This week combines baselines, configuration ownership, unnecessary services, updates, secure defaults, rollback, and verification. Students will harden a fictional host by changing one documented condition at a time and proving required function survives.

This week

1. A Baseline Makes Configuration Drift Visible — define expected services, packages, settings, and ownership.
2. Reduce What the System Does Not Need — disable or narrow one unnecessary function in the fictional model and test impact.
3. Every Hardening Change Needs Rollback and Retest — build a controlled change record with precheck, change, evidence, recovery, and regression tests.

Evidence artifact

Create a Hardening Change Dossier with baseline configuration, one justified reduction, one update/configuration change, rollback plan, negative and positive retests, and residual risk.