Drive-by Download

The expression 'drive-by download' is used in four increasingly common meanings:

1. Downloads which the user indirectly authorized but without understanding the consequences. For example: by installing an unknown ActiveX component or Java applet.

Note that Microsoft Internet Explorer uses the ActiveX scripting language, whereas Mozilla Firefox does not; thus, many argue that Firefox is considerably more secure than Internet Explorer because it is not susceptible to ActiveX-based attacks. (Source: cnet.com)

2. Any download that happens without knowledge of the user.

3. A download of spyware, a computer virus or any kind of malware that happens without knowledge of the user.

Drive-by downloads may happen by visiting a website, viewing an email message or by clicking on a deceptive popup window: the user clicks on the window in the mistaken belief that, for instance, it is an error report from his own PC or that it is an innocuous advertisement popup; in such cases, the "supplier" may claim that the user "consented" to the download though s/he was completely unaware of having initiated a malicious software download.

4. Download of malware through exploitation of a web browser, email client or operating system bug, without any user intervention whatsoever. Websites that exploit the Windows Metafile vulnerability may provide examples of "drive-by downloads" of this sort.

Drive-by Installation Vs Drive-by Download

The expression drive-by install (or installation) is completely analogous and refers to installation rather than download (though sometimes the two are used interchangeably).

Drive-by Download Trends

In April 2007 researchers at Google discovered hundreds of thousands of web pages performing drive-by downloads.

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