But since that announcement, which directed concerned users to a website which promptly crashed for more than 15 hours, many BBC readers have been in touch wondering what they need to do to stay safe on the internet. Here's an at-a-glance guide.
Am I affected?
If you are using Windows, read on.
Gameover Zeus is a particularly nasty piece of malware - malicious software - that will fish around your computer for files that look like they may contain financial or other sensitive information. Once it finds them, it steals themread more