Drive-by downloads are a common method of spreading malware. Cybercriminals look for insecure web sites and plant a malicious script into HTTP or PHP code on one of the pages. This script may install malware directly onto the computer of someone who visits the site, or it may take the form on an IFRAME that re-directs the victim to a site controlled by the cybercriminals. In many cases the script is obfuscated, to make it more difficult for security researchers to analyse the code. Such attacks are called ‘drive-by downloads’ because they require no action on the part of the victim — beyond simply visiting the compromised web site: they are infected automatically (and silently) if their computer is vulnerable in some way (e.g. if they have failed to apply a security update to one of their applications).