Ransomware is a form of malware that gives criminals the ability to lock a computer from a remote location – then displays a pop-up window informing the owner that it will not be unlocked until a sum of money is paid. In some cases, the only usable part of the computer is the number keypad to enter a PIN to enable payment to the criminals. The widest-known varieties of ransomware in recent times are CryptoLocker and WannaCry. An additional twist is that an accusation of illegal activity or a pornographic image appears on the locked screen, making it more difficult for some users to seek help from anybody else, and simply resort to paying the ransom.

The risks

Your computer could be infected by ransomware such as CryptoLocker or WannaCry when you inadvertently:
  • Open a malicious attachment in an email.
  • Click on a malicious link in an email, instant message, social networking site or other website.
  • Visit a corrupt website – often these are of a pornographic nature.
  • Open infected files from web-based digital file delivery companies (for example Hightail – formerly called YouSendIt, and Dropbox).
  • Open corrupt macros in application documents (word processing, spreadsheets etc).
  • Connect corrupt USB connected devices (eg memory sticks, external hard drives, MP3 players).
  • Insert corrupt CDs/DVDs into your computer.

Avoiding ransomware

  • Do not reply to, or click on links contained in, unsolicited or spam emails from companies or individuals you do not recognise.
  • Visit only websites you know to be reputable.
  • Always install updates to software and apps – including operating systems – as soon as prompted.
  • Ensure you have effective and updated antivirus/antispyware software and firewall running before you go online.
  • Regularly back up all your data, including to a USB-connected device stored remotely from your computer. This is because some ransomware can also infect your cloud-based storage.

If you have ransomware on your computer

  • To detect and remove ransomware and other malicious software that may be installed on your computer, run a full system scan with an appropriate, up-to-date, security solution.
  • If your computer has been locked by ransomware, seek professional advice from a trustworthy source.

If you’ve experienced cybercrime, you can contact the charity Victim Support for free and confidential support and information.



In partnership with

Jargon Buster

A Glossary of terms used in this article:


The technology used to store sound files, typically for music or podcasts.


Personal Identification Number.