Web Security, Privacy & Commerce, 2nd Edition

Web Bugs

In September 2000, the Colorado-based Privacy Foundation^[105] released a report on a new technology for monitoring Internet users, which the foundation called web bugs . Although the use of this technology had been widely known in advertising circles, it had not previously been publicized to the larger community of Internet users.

Web bugs are small graphic images placed on web pages or in email messages to facilitate third-party tracking of users and collection of statistics. A typical web bug consists of a 1-pixel-by-1-pixel transparent GIF, making it invisible to the unassisted eye. To see a web bug, you must view the source of an HTML page or email message.

According to the foundation’s Web Bug FAQ:^[106]

The word bug is being used to denote a small, eavesdropping device. It is not a euphemism for a programming error.... Rather than the term `Web bugs,’ the Internet advertising community prefers the more sanitized term `clear GIF.’ Web bugs are also known as `1-by-1 GIFs,’ `invisible GIFs,’ and `beacon GIFs.’

Web Bugs on Web Pages

Here are two web bugs that the Privacy Foundation found on the Intuit’s home page for Quicken.COM:

<img src="http://ad.doubleclick.net/ad/pixel.quicken/NEW" 
width=1 height=1 border=0>

<IMG WIDTH=1 HEIGHT=1 border=0 
SRC="http://media.preferences.com/ping?ML_SD=IntuitTE_Intuit_1x1_RunOfSite_Any&db_
afcr=4B31-C2FB-10E2C&event=reghome&group=register&time=1999.10.27.20.5 6.37">

The first web bug causes a single 1 x 1 image to be fetched from the Doubleclick ...