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Nano-lesson · usually takes 2–3 minutes

Ransomware & malware — react the right way

How ransomware gets in — and what to do in the first few minutes.

The day WHSmith couldn't process a single sale

One morning in 2022, none of the country's Currys stores could ring up a purchase — the tills were locked by ransomware, and every store had to close. Ransomware is a program that locks files and systems and demands a ransom. It usually gets in via a phishing email, a stolen password or a click on an attachment.

Prevent it

  • Never enable macros, and only open files you're expecting.
  • Keep your operating system and programs updated.
  • Report suspicious emails early — before anyone clicks.

An unexpected invoice with a .zip?

That's a classic way to smuggle in malicious programs. Only open files you're expecting — never a .zip or an "enable macros" prompt from a sender you don't know. If in doubt: ask IT before you click.

If the worst happens

Files get locked in a ransomware attack, and a ransom message pops up — what do you do?

Does this look familiar?

  • Disconnect from the network immediately (unplug the cable / turn off Wi-Fi) so the attack doesn't spread to shared drives and colleagues.
  • Don't switch off the computer in a panic. Leave it running — but offline — so IT can preserve evidence and possibly your files; a hard shutdown can make the damage worse.
  • Never pay the ransom. It funds the criminals and rarely gets your files back.
  • Call IT immediately — speed limits the damage.

Remember

Disconnect from the network, don't pay, and call IT straight away.

What the research says

Ransomware appeared in ~44% of data breaches in 2025 (up from 32%), and stolen credentials (~22%) are the most common entry point — often harvested via phishing and reused against organisations without MFAMulti-factor authentication (MFA/2FA): an extra step beyond your password — such as a code or a tap on your phone — so a thief can't log in with the password alone.. That's why MFA is the single measure with the biggest impact against ransomware.

Verizon DBIR 2025 · Microsoft Research 2023.

Question 1 of 3

Your screen suddenly shows a ransom message, and your files won't open. What's the FIRST thing you do?

Question 2 of 3

You accidentally opened the .zip file from an unexpected "invoice" email. The computer seems completely normal. What do you do?

Question 3 of 3

Your computer wants to restart to install an update — right in the middle of your busiest week. What do you do?

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