Surprise! Ad companies tracking people who don’t want to be tracked

by David Solomonoff

The Stanford Security Lab has been developing a system for automated enforcement of Do Not Track by detecting the myriad forms of third-party tracking, including cookies, HTML5 storage, fingerprinting, etc. Starting with advertising companies participating in the self-regulatory Network Advertising Initiative (NAI), they navigated popular websites and  identified tracking content (primarily ads and beacons) from 64 of the 75 NAI member companies.

Their tests involved loading content from the company’s site, opting out of being tracked on the NAI website,  reloading the content, then checking for cookies.

Half of the NAI members tested did not remove their tracking cookies after opting out.

NAI member companies pledge only to allow opting out of behavioral ad targeting, not tracking. Of the 64 companies we studied, 32 left tracking cookies in place after opting out.

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