Through malware on a legitimate website, a program is downloaded to a user’s system just by visiting the site. It doesn’t require any type of action by the user to download.

Typically, a small snippet of code is downloaded to the user’s system and that code then reaches out to another computer to get the rest and download the program. It often exploits vulnerabilities in the user’s operating system or in different programs, such as Java and Adobe.

The best way is to be sure all of your operating systems and software programs are up to date. This lowers your risk of vulnerability. Additionally, try to minimise the number of browser add-ons you use as these can be easily compromised. For example, if your computers don’t need Flash or the Java plug-in, consider uninstalling them.