A castle has more than one wall
A castle has a moat, an outer wall, an inner wall and a locked keep. If an attacker gets over the first wall, the next one is waiting.
Good security works the same way. No single control is perfect, so you plan for the day one of them fails.
By the end of this lesson
Note
I can match each risk with two or more layers of defence, so one failure does not open the door.
Key words
| Word | What it means |
|---|---|
| Mitigation | an action that makes a risk smaller |
| Layered defence | using several controls so that if one fails, another still protects |
| Control | a measure that reduces a risk, such as a lock or a setting |
| Fail safe | a design where a failure leaves things safe, not open |
| Attack vector | a route an attacker could use to get in |
| Least privilege | giving each person only the access they need |
| Firewall | a device or program that blocks some messages and lets others through |
| Encryption | scrambling data so only the right key can read it |
| Phishing | a fake message that tricks you into giving away details |
| Malware | a harmful program, such as a virus |
| Authentication | proving who you are, such as with a password |
| Procedure | a set of steps that is always followed in the same way |
The cells students fill in are left blank in this preview.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Worked example: two layers for each risk
| Risk | Layer 1 | Layer 2 | If layer 1 fails |
|---|---|---|---|
| Phishing email | A mail filter blocks most fake emails | Staff training on spotting the rest | Training still protects |
| Stolen laptop | Locked doors and a laptop lock | Disk encryption, so the data is unreadable | Data stays safe |
| Open port on the server | A firewall with default deny | The service is turned off if it is not needed | The port is not listening |
| Power cut | A battery backup keeps the server running | A safe shutdown and a nightly backup | No data is lost |
The cells students fill in are left blank in this preview.
Use accepted good practice
You do not have to invent controls. Industry has agreed a core set. The UK scheme Cyber Essentials lists five: firewalls, safe settings, control of who has access, protection from malware, and keeping software up to date.
Add backups, encryption, a second check when signing in (multi-factor authentication) and staff training. Name the tool or the procedure, not only the idea.
Check
Have a go
Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.