Anyone who is using Internet Explorer (especially IE8 and IE9) needs to be aware of a “zero day” exploit that is “in the wild” and affecting users, downloading malicious code to their machines automatically.
The episode has prompted the first Microsoft emergency fix-it patch for many months.
Along with the patch, there are also several pieces of advice or settings that users should user as a matter of course to protect themselves against the rising tide of hackers and exploits. These include things like not using a user account on your PC with Administrator rights for day-to-day activities and ensuring that you have an up to date virus scanner installed.
There are many articles on the subject out there, including http://www.bbc.co.uk/news/