Drive-by downloads are downloads of software, adware, or malware that is either authorized by the user without understanding the consequences or downloaded without the knowledge of the user. This can occur by visiting nefarious websites, clicking on links in email, or clicking on a pop-up ad. Often times drive-by downloads are spyware, viruses or other malware. Pop-up windows can be deceptively designed to mimic computer error messages that trick users into downloading the software by clicking the “ok” button. Drive-by downloads have historically been known for taking advantage of the Windows metafile vulnerability. Even though security warning messages may pop up on sites before software is downloaded, the name of the software is often vague and the site may provide the visitor with no information as to what or how many software programs will be installed. Some sites can install up to 10 different programs on a user’s machine with just one click of the “yes” button. Drive-by downloads can install various software types that are supposed to be “helpful” to the user: toolbars, browser and desktop modifications, windows dialog box advertisements, and pop-up advertisements. It should be noted that not all drive-by downloads contain malware, some simply contain adware; but often the site or the pop-up windows do not give consumers the information they need to make an informed decision about whether or not to download software.