Ransomware on Monday, back to work by lunch
On Monday ransomware (harmful software that locks files) locks every file in a small firm. The owner stays calm.
She has a backup from Sunday night, stored on a disk kept apart from the other computers. By lunch, the files are back.
A good backup turns a disaster into a bad morning. Today you learn the kinds, and the other habits that keep systems safe.
By the end of this lesson
Note
I can describe three kinds of backup and say how updates and air gaps reduce risk.
Key words
| Word | What it means |
|---|---|
| Backup | A copy of data kept safe in case the first is lost. |
| Full backup | A copy of all the data. |
| Incremental backup | A copy of only what changed since the last backup of any kind. |
| Differential backup | A copy of everything that changed since the last full backup. |
| Restore | Putting backed-up data back. |
| Off-site | Stored in a different place from the original. |
| Update | A new version of software that fixes weaknesses or adds features. |
| Firmware | Software stored inside a device, such as a router. |
| Driver | Software that lets the computer talk to a device such as a printer. |
| Air gap | A computer or network with no connection at all to other networks. |
| Network | Computers joined together so they can share data. |
| Malware | Harmful software. |
| Router | A device that passes traffic between networks. |
| Ransomware | Malware that locks files and demands money. |
The cells students fill in are left blank in this preview.
Starter: what you already know
Have a go
Starter: what you already know
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Cycle 1: three kinds of backup
Full backup. Everything, every time. Slow and big, but one set is all you need to restore.
Incremental backup. Only what changed since the last backup of any kind. Fast and small, but to restore you need the full backup plus every incremental after it.
Differential backup. Everything changed since the last full backup. Bigger each day, but you need just two sets to restore.
Worked example: files in each backup
| Day | Full (1000 files) | Incremental | Differential |
|---|---|---|---|
| Sunday: full backup | 1000 | 1000 | 1000 |
| Monday: 10 files change | 1000 | 10 | 10 |
| Tuesday: 10 more change | 1000 | 10 | 20 |
| Wednesday: 10 more change | 1000 | 10 | 30 |
| Restore on Wednesday needs | 1 set | Sunday + Monday + Tuesday + Wednesday: 4 sets | Sunday + Wednesday: 2 sets |
The cells students fill in are left blank in this preview.
Safe storage
A backup next to the original is lost in the same fire. Keep backups safe:
Off-site or in the cloud, in another place.
Disconnected from the network, so ransomware cannot reach them.
Locked and encrypted, so a thief cannot read them.
Tested. A backup you have never restored is a hope, not a backup.
Check: backups
Have a go
Check: backups
4 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.