When you tell Chrome to wipe private data about you, it spares two websites from the purge: Google.com, YouTube

Google exempts its own websites from Chrome’s automatic data-scrubbing feature, allowing the ads giant to potentially track you even when you’ve told it not to.

Programmer Jeff Johnson noticed the unusual behavior, and this month documented the issue with screenshots. In his assessment of the situation, he noted that if you set up Chrome, on desktop at least, to automatically delete all cookies and so-called site data when you quit the browser, it deletes it all as expected – except your site data for Google.com and YouTube.com.

While cookies are typically used to identify you and store some of your online preferences when visiting websites, site data is on another level: it includes, among other things, a storage database in which a site can store personal information about you, on your computer, that can be accessed again by the site the next time you visit. Thus, while your Google and YouTube cookies may be wiped by Chrome, their site data remains on your computer, and it could, in future, be used to identify you.

Johnson noted that after he configured Chrome to wipe all cookies and site data when the application closed, everything was cleared as expected for sites like apple.com. Yet, the main Google search site and video service YouTube were allowed to keep their site data, though the cookies were gone. If Google chooses at some point to stash the equivalent of your Google cookies in the Google.com site data storage, they could be retrieved next time you visit Google, and identify you, even though you thought you’d told Chrome not to let that happen.

Ultimately, it potentially allows Google, and only Google, to continue tracking Chrome users who opted for some more privacy; something that is enormously valuable to the internet goliath in delivering ads. Many users set Chrome to automatically delete cookies-and-site-data on exit for that reason – to prevent being stalked around the web – even though it often requires them to log back into websites the next time they visit due to their per-session cookies being wiped.

Yet Google appears to have granted itself an exception. The situation recalls a similar issue over location tracking, where Google continued to track people’s location through their apps even when users actively selected the option to prevent that. Google had put the real option to start location tracking under a different setting that didn’t even include the word “location.”

In this case, “Clear cookies and site data when you quit Chrome” doesn’t actually mean what it says, at least not for Google.

There is a workaround: you can manually add “Google.com” and “YouTube.com” within the browser to a list of “Sites that can never use cookies.” In that case, no information, not even site data, is saved from those sites, which is all in all a little confusing.

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Source: When you tell Chrome to wipe private data about you, it spares two websites from the purge: Google.com, YouTube • The Register