  The privacy implications of third-party tracking is a well-studied problem.
Recent research has shown that besides data aggregators and behavioral
advertisers, online social networks also act as trackers via social widgets.
Existing cookie policies are not enough to solve these problems, pushing users
to employ blacklist-based browser extensions to prevent such tracking.
Unfortunately, such approaches require maintaining and distributing blacklists,
which are often too general and adversely affect non-tracking services for
advertisements and analytics. In this paper, we propose and advocate for a
general third-party cookie policy that prevents third-party tracking with
cookies and preserves the functionality of social widgets without requiring a
blacklist and adversely affecting non-tracking services. We implemented a
proof-of-concept of our policy as browser extensions for Mozilla Firefox and
Google Chrome. To date, our extensions have been downloaded about 11.8K times
and have over 2.8K daily users combined.
