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Some browsers presenting Google Analytics cookies but no GA on my site

Site has never used GA, what is setting those cookies?

8:19 pm on Jan 9, 2013 (gmt 0)

I recently started logging complete headers as part of a fraud prevention scheme I'm working on. I noticed that some browsers (roughly 5%) are presenting cookies that my site has never set. Here's an example:

Cookie: __utma=154678586.1280061223.1357677819.1357677819.1357758130.2; __utmb=154678586.0.10.1357758130; __utmz=154678586.1357677819.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=chat%20bot.com; __utmc=154678586; <...more cookies that my site did actually set follow>

These appear to be Google Analytics cookies, yet I have never used GA on this site, nor have I used any tracking software which sets cookies (the site is 100% original code)

I haven't yet fully analysed the data but so far the most common user-agent to do this seems to be:

Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.97 Safari/537.11

(I presume this is a Google Chrome browser on a Mac, including the Safari name for compatibility reasons?)

Anyone know why it is setting these cookies?
10:38 pm on Jan 9, 2013 (gmt 0)

WebmasterWorld Senior Member lucy24 is a WebmasterWorld Top Contributor of All Time Top Contributors Of The Month

Y'know, as soon as I saw the subject line I thought: The answer is going to involve G### Chrome. Crystal ball says Chrome is writing home to report on where it's been.

I presume this is a Google Chrome browser on a Mac, including the Safari name for compatibility reasons?

Why do you presume this, when it explicitly says "Windows NT 6.1" and explicitly doesn't say "Mac OS X 10_something"?

The "Safari" at the end is part of the standard Chrome UA. Almost everything using WebKit includes it; you'll also see it on mobiles.
3:09 am on Jan 10, 2013 (gmt 0)

Whoops, I totally missed the "Windows NT" part of the user agent - can I plead lack of sleep? :)

Anyway, still curious as to why Chrome is doing this. I can't think of how G would be able to see the contents of third party cookies on a site that DOESN'T have any inline javascript controlled by G (such as the code to include analytics). I'm not quite paranoid enough to suggest that Chrome might be doing something a little different to other browsers in that regard.

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