OK, so I noticed that on every page load (at least here and on Stack Overflow but guess on any Stack Exchange site) there is request for that external JS file: http://b.scorecardresearch.com/beacon.js
(source)
Who are we signalling to? For what purpose?
Seriously now, this JS is generating a pixel aka Web bug but I couldn't find anywhere what Stack Exchange is doing with this information or who can access it.
I went through the Privacy Policy and found reference to Google Analytics which is totally fine, but the beacon or http://scorecardresearch.com (beacon host) are not mentioned there.
This is a sample of the data passed using the beacon:
The marked number is the same on all sites and doesn't change per page so it's either user based or machine based.
Can I get some details about this?
Update: following this comment I checked the page source and indeed c2
appears to be the Stack Exchange ID:
_comscore.push({ c1: "2", c2: "17440561" });
So from what I see, they just measure amount of page hits, without actually collect anything user or browser related.
c2
value seems to be a constant. i.imgur.com/9YfmUgU.pngCookie:UID=2f481431-82.166.201.187-1365072703; UIDR=1365072703
. With this cookie, they can (probably) track you in any site you visit that is using the same service. Even without a direct user ID, it is almost trivial to know who you are - it is probably the profile you visit most. They can also check pages like/users/edit/{ID}
, which only you can open. I doubt they're just collecting page hits - the SE team can easily do that on server side. Either way I don't like these "services".__qca
cookie for gravatar.com when visiting www.gravatar.com directly though.