Module 2 · Defending a small network Lesson 6 of 15
Patching, backups and the boring controls that work
Unpatched software and untested backups cause more real damage than clever attacks. Both are boring, and both are what separates a defended system from a hopeful one.
The concept
The unglamorous controls stop the attacks that actually happen: automatic updates on, backups that are tested by restoring one, least privilege so nobody has more access than the task needs, and disk or database encryption. None of them make an interesting demonstration, and all of them are in the list of top breaches every year.
A backup is not a backup until you have restored from it and checked the data is usable. Automate it, keep one copy somewhere the main system cannot reach — because ransomware encrypts attached drives too — and put a date in your calendar to restore one for real.
sudo apt update && sudo apt list --upgradable
sudo apt upgrade -y
# Backups: 3 copies, 2 media, 1 off-site (3-2-1)
# Test a RESTORE, not just a backup - an untested backup is only a hope.
# The controls that actually stop incidents: patch, backup, MFA,
# least privilege. Boring, and they work.Common mistakes
The mistake is a backup job that has been failing for months while the log line says it ran. Check the exit status and the file size, and restore once a quarter. Security is mostly maintenance, and maintenance is mostly noticing.
Worked example
A backup that has never been restored is not a backup. Restoring one file from last week, on purpose, once, is the only way to know.
Your practice task
Take a backup of something you care about, restore one file from it, and write down how long it took and what you would lose today.
Do this before moving on. Reading a solution teaches the shape of it; typing it teaches you.
Key takeaway
The unglamorous controls stop the attacks that actually happen: automatic updates on, backups that are tested by restoring one, least privilege so nobody has more access than the task needs, and disk or database encryption. None of them make an interesting demonstration, and all of them are in the list of top breaches every year.
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