Q&A: How to protect your computer from cyberattack

What to do when you log onto your computer at work today

Source code: WannaCry has affected computers in at least 150 countries. Photograph: Ritchie B Tongo/EPA

What computers are affected by the cyber


The virus or malware that has affected at least 150 countries this weekend primarily targets PCs and laptops that still use Windows XP. This software, which Microsoft released in 2001, was one of the most common operating systems of the 2000s. The company stopped supporting it – meaning that it issued no more updates, to fix problems – in 2014. That has left Windows XP particularly exposed to new methods of hacking. More recent Microsoft systems, including Windows 10, 8 and 7, can also be infected by the ransomware virus. In March the company released a patch, or security upgrade, to protect computers against the ransomware involved in this weekend's attack.

What is ransomware?

Ransomware is a virus that locks your computer or web browser, then displays a demand for payment, usually in the online currency Bitcoin, in return for unlocking your files. The virus can target home computers or servers that businesses and state agencies use. WannaCry, the virus involved in the current attack, is thought to be based on software developed by the US National Security Agency. The attack that targeted the NHS, in the UK, asked for $300 worth of Bitcoin to unlock each computer. Microsoft says payment does not guarantee unlocking. WannaCry is spread mainly via email. Europol, the EU law-enforcement agency, has advised people to be wary of clicking on links in or downloading attachments from any emails from senders they do not recognise. The spread of the current attack was stopped by an anonymous UK cybersecurity researcher, who discovered that by registering an unusual domain name that had been written into the ransomware he could get the virus to shut itself down. The creators of the virus might have included the web address as a kill switch, in case they wanted to stop it spreading any further; the name might also have been included as protection against the ransomware being analysed by cybersecurity experts.

How can I protect my computer from the ransomware virus?

If you still use Windows XP you should upgrade to a more recent operating system, as this will help to secure your computer. Microsoft’s current operating system is Windows 10. Two slightly older versions, Windows 8.1 and Windows 7, are also still available.

My computer doesn’t run Windows XP. Am I safe?

Even if you use a more recent Windows system you should ensure you have downloaded the latest updates and security software, to protect against viruses or malware. The security patch that Microsoft released in March, named MS17-010, can be found online. Windows 10, 8.1 and 8 all include Microsoft's Windows Defender antivirus software. This guards against many types of malware and ransomware. If you're using Windows 7 you can download Microsoft's free Windows Security Essentials software. This will also help protect against viruses.


Any other advice?

Microsoft advises users to avoid clicking on links in or downloading attachments from emails from senders you do not recognise. It also says to block pop-ups adverts, which will stop most potentially dangerous pop-up windows with harmful links appearing on your screen.

What should I do if my computer has been infected?

As there are different types of ransomware, there is no single, easy solution to restore your computer if it has been infected. If the ransomware has just blocked access to your web browser, it may be possible to regain control by accessing your computer's task manager and shutting down the program. If the ransomware has locked your entire PC, as WannaCry has done, combating it is more difficult. You may have to download safety software on to an uninfected computer, then try to transfer it to the affected computer via a CD-Rom or USB stick. You can find detailed instructions at microsoft.com

Jack Power

Jack Power

Jack Power is acting Europe Correspondent of The Irish Times